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1
Tylstedt, Sven. "The Human Spiral Ganglion." Doctoral thesis, Umeå University, Clinical Sciences, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-77.
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Our knowledge of the fine structure of the Human Spiral Ganglion (HSG) is still inadequate and new treatment techniques for deafness using electric stimulation, call for further information and studies on the neuronal elements of the human cochlea. This thesis presents results of analyses of human cochlear tissue and specimens obtained during neurosurgical transpetrosal removal of life-threatening meningeomas. The use of surgical biopsies produced a well-preserved material suitable for ultrastructural and immunohistochemical studies on the human inner ear. The SG was studied with respect to fine structure, using TEM technique and the immunostaining pattern of synaptophysin, which is an integral membrane protein of neuronal synaptic vesicles. The immunostaining patterns of the tight junctional protein ZO-1 and the gap junctional proteins Cx26 and Cx43 in the human cochlea were also studied. The ultrastructural morphology revealed an absence of myelination pattern in the HSG, thus differing from that in other species. Furthermore, formation of structural units as well as signs of neural interaction between the type 1 neurons could be observed. Type 1 cells were tightly packed in clusters, sharing the ensheathment of Schwann cells. The cells frequently made direct physical contact in Schwann cell gaps in which membrane specializations appeared. These specializations consisted of symmetrically or asymmetrically distributed filamentous densities along the apposed cell membranes. The same structures were also present between individual unmyelinated nerve fibres and the type 1 cells. Synapses were observed on the type 2 neurons, with nerve fibres originating from the intraganglionic spiral bundle. Such synapses, though rare, were also observed on the type 1 cells. The ultrastructural findings were confirmed by the synaptophysin study. A 3-D model of a Schwann cell gap between two type 1 cells was constructed, describing the distribution pattern of membrane specializations. In the immunohistochemical studies on the human cochlea, ZO-1 was expressed in tissues lining scala media, thus contributing to the formation of a closed compartment system, important for the maintenance of the specific ionic composition of the endolymph. Protein Cx26 could be identified in non-sensory epithelial cells of the organ of Corti, in connective tissue cells of the spiral ligament and spiral limbus, as well as in the basal and intermediate cell layers of stria vascularis. Cx26 in this region may be involved in the recycling of potassium. Protein Cx43 stained weakly in the spiral ligament, but intense staining in the SG may indicate that gap junctions exist between these neurons. A different functional role for the HSG can be assumed from the morphological characteristics and the signs of a neural interaction between the SG cells. This might be relevant for neural processing mechanisms in speech coding and could have implications for cochlear implant techniques.
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Bailey, Erin M. "Why do spiral ganglion neurons die after deafening?" Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4568.
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Hair cells, the auditory sensory cells, are the sole afferent input to the spiral ganglion neurons (SGNs). HCs and adjacent organ of Corti supporting cells provide neurotrophic factors that prevent SGN degeneration. Following loss of hair cells, SGNs degenerate and gradually die. Most deafness, whether congenital, age-related, or due to noise, disease, trauma, or ototoxin, is a consequence of hair cell loss. Cochlear implants, the only means of restoring hearing to deaf people, electrically stimulate the SGNs, replacing the sensory function of hair cells. SGN degeneration compromises the efficacy of cochlear implants. For example, degeneration of the peripheral process raises the threshold for electrical stimulation, necessitating higher currents that reduce battery life and, by stimulating SGNs in a larger volume, reduce the precision of frequency representation. The goal of my research is to determine why SGNs degenerate or die so that therapies can be developed to prevent it. My approach to this goal focuses on answering two significant questions.
First, because the death of SGNs does not occur immediately after hair cell loss implies that hair cells are not the sole source of neurotrophic support for SGNs. Some neurotrophic support must be available even after hair cells are gone. What are the sources of neurotrophic factors for SGNs after hair cells are lost and why are they ultimately insufficient to prevent SGN death? In Chapter II I answer this question by quantifying neurotrophic factor expression in regions accessible to the SGNs: the organ of Corti and the cochlear nucleus. Answering this question will identify the key endogenous factors that support SGNs, which will facilitate development of optimal therapies.
Second, the fact that SGNs die over a long period of time raises the possibility that there is a difference between SGNs that die early and those that die weeks or months later. Is the time a cell dies purely stochastic or is there something distinctive about cells that die at different times? In Chapter III, I use microarray-based gene expression profiling to compare the initial population of SGNs at the onset of SGN death to a population of SGNs still surviving at a time when about half of the SGNs have already died. Identifying distinctive molecular features in the population of cells that can survive longer in the absence of hair cells may suggest therapeutic approaches to preventing SGN degeneration or death. Finally, Chapter IV addresses some of the molecular features identified by the microarray-based profiling by examining their role in SGN degeneration.
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Huang, Jie. "Depolarization-dependent pro-survival signaling in spiral ganglion neurons." Diss., University of Iowa, 2007. https://ir.uiowa.edu/etd/214.
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Membrane depolarization is an effective neurotrophic stimulus, with its trophic effect on spiral ganglion neurons (SGNs) even surpassing that of neurotrophins. Thus, SGN cultures are a favorable system to investigate pro-survival signal transduction downstream of depolarization.
Depolarization promotes SGN survival by recruiting three distinct kinase pathways: cyclic AMP-dependent protein kinase (PKA), Ca2+/calmodulin-dependent protein kinase II (CaMKII) and CaMKIV. CaMKIV mediates the pro-survival effect of depolarization by activating CREB in nucleus. However, the mechanisms by which PKA and CaMKII promote survival are still not clear. By targeting constitutively active PKA or a PKA inhibitor (PKI) to the outer mitochondrial membrane (OMM), we showed that PKA activity at the OMM is sufficient to support SGN survival in the absence of other trophic factors and necessary for cAMP-dependent SGN survival. It has been suggested that PKA can promote survival by inactivating pro-apoptotic protein Bad. By cotransfection of SGNs with OMM-PKA and wild-type Bad, we showed that this was the case. We further showed that Ser112 and Ser136 in Bad, but not Ser155, a hypothetical PKA target, were necessary for functional inactivation of Bad by PKA.
CaMKII mediates the third depolarization-dependent pro-survival pathway. A specific pro-survival target for CaMKII was identified through a separate investigation of the pro-apoptotic JNK-Jun signaling pathway, which we had identified as active in apoptotic SGNs in vivo. By measuring anti-phosphoJun immunofluorescence, we could quantify JNK-Jun activation in SGNs under different conditions. We showed that JNK inhibition or genetic deletion of JNK3 reduces SGN death after neurotrophic factor withdrawal. Neurotrophins have been shown to suppress JNK activation via their receptor protein tyrosine kinases (PTKs). By expressing constitutively active and dominant negative forms of candidate protein kinases, we identified a novel signaling pathway linking depolarization to JNK: Ca2+ entry - CaMKII - FAK/Pyk2 - PI-3-OH Kinase - Protein Kinase B - inhibition of MLKs (upstream activators of JNK). Thus, depolarization also recruits PTKs - the nonreceptor PTKs FAK and Pyk2 - to suppress JNK activation, implying a conserved PTK-PI3K-PKB pathway for suppression of pro-apoptotic JNK activation by neurotrophic stimuli.
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Galindo, Ramon Gustavo. "The effect of neurotrophic factors on spiral ganglion neurons." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3456.
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The current study investigates the survival and neuritogenic effects of various neurotrophic factors on rat spiral ganglion neurons (SGNs) in vitro. In particular, ciliary neurotrophic factor (CNTF), glial derived neurotrophic factor (GDNF), neurotrophin-3 (NT-3) and neurturin (NRTN) were assayed on postnatal day 4-6 SGNs. CNTF and NT-3 produced a robust survival effect while GDNF and NRTN failed to do so. A dose response revealed CNTF to be effective at promoting survival as low as 5ng/ml. In addition, CNTF promoted neurite growth in both depolarizing and non-depolarizing conditions, suggesting that CNTF can partially overcome the inhibitory effect of membrane depolarization. Lastly, the effect of NTFs was assayed between basal and apical neurons in culture. The preliminary results suggest there is no difference in response to NTFs between these two spatially distinct populations, however, it was noted that under depolarizing conditions apical neurons produce significantly shorter neurites than their basal counterparts.
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Zabalawi, Hassan A. "Spiral ganglion neurite outgrowth and pathfinding on electrospun microfibrous piezoelectric nanocomposite polymer scaffolds." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10061643/.
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Sensorineural hearing loss (SNHL) can be caused by hair cell loss and spiral ganglion neurone (SGN) degeneration. Cochlear implants (CIs), the only means of restoring residual hearing to profoundly deaf people, stimulate possible preserved SGNs electrically. Thus, SGN degeneration dictates the efficacy of CIs. SGN degeneration reduces sensitivity and frequency selectivity. In addition, stimulation thresholds increase due to SGN degeneration consequently increasing power demands. The replacement of auditory neurones with proper functional spatial alignment is an important step in the attempt to restore auditory function. This study adopts a tissue-engineering approach. We examined the viability of polyvinylidene fluoride (PVDF) and polyvinylidene trifluoroethylene (P(VDF-TrFE)). P(VDF-TrFE) was chosen to add directional growth cues through electrospinning aligned microfibrous scaffolds. The effects of the scaffolds on the length and orientation of re-growing SGN neurites and glia were tested in vitro using primary murine cultures. Two methods of SGN preparation were compared; explants and dissociated cultures. Primary SGNs showed preferential affinity to P(VDF-TrFE) microfibres and the microfibrous scaffolds were found to promote aligned SGN neurite regrowth compared to glass coverslips. Subsequently, we doped the electrospun P(VDF-TrFE) microfibres with carbon nanotubes (CNT) to optimise the scaffold mechanically and electrically. The CNT addition was found to be biocompatible and promoted aligned SGN neurite regrowth. The CNT doping enhanced the mechanical properties of the microfibres and improved scaffold handling. Moreover, the scaffolds could be biofunctionalized with neurone modulating drugs. Preliminary testing of gamma-secretase inhibitor (LY411575) showed promising regenerative effects on SGNs in vitro. In conclusion, electrospun aligned microfibrous P(VDF-TrFE)-CNT nanocomposite scaffolds can modulate glial and SGN neurite and axon organization in vitro. Combined with a specific protocol of electrical induction in the first weeks of implantation, the piezoelectric fibrous scaffold could significantly improve cochlear implantation results, frequency selectivity and minimize power demands.
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Browne, L. P. "An investigation of lipid modulation of low voltage activated currents in spiral ganglion neurons." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1477267/.
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Type I spiral ganglion neurons (SGNs) synapse onto cochlear inner hair cells and constitute the majority of afferent fibres in the auditory nerve (AN). Better characterisation of their biophysical properties may identify therapeutic targets for optimising AN sensitivity. This study aimed to characterise the membrane physiology underlying the firing properties of post-hearing onset SGNs and investigated whether their properties could be modified by the presence of native and synthetic lipids. In dissociated ganglionic cultures, SGNs displayed an intrinsic variation in their firing properties; this could be correlated with the magnitudes of specific membrane currents. SGNs were categorised by their response to depolarising current injection; SGNs either adapted to the stimulus rapidly, slowly or not at all. Rapid adaptation, a mechanism that preserves temporal precision throughout the auditory system, was found to be regulated by a dendrotoxin-K (DTX-K) and tityustoxin-Kα (TsTx)-sensitive low-threshold voltage-activated (LVA) K+ current, suggesting contribution by Kv1.1 and Kv1.2 subunits. As Kv1.2 channels were known to be positively modulated by membrane phosphoinositides, we investigated the influence of phosphatidylinositol-4,5- bisphosphate (PIP2) availability on SGN K+ currents. Inhibiting PIP2 production using wortmannin, or sequestration using a palmitoylated peptide (PIP2-PP), slowed or abolished adaptation in SGNs. PIP2-PP specifically reduced SGN LVA currents in a manner that was partly rescued by intracellular dialysis with diC8PIP2, a nonhydrolysable analogue of PIP2. PIP2-PP application induced similar levels of current inhibition in Kv1.1/Kv1.2 channels heterologously expressed in HEK293 cells. Accordingly, the lipid sensitivity of the Kv1.2 channel was further explored with a range of native and synthetic free fatty acids. Polyunsaturated fatty acids were found to be strong inhibitors of Kv1.2 currents, offering further potential candidates for SGN modulation. Collectively, this data identifies Kv1.1 and Kv1.2 containing K+ channels as key regulators of excitability in the AN, and potential targets for pharmacological modulation.
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Fryatt, Alistair Gordon. "Investigating voltage-gated sodium channel expression in rat spiral ganglion neurons following noise induced hearing loss." Thesis, University of Leicester, 2010. http://hdl.handle.net/2381/10207.
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Noise exposure has been shown to elevate hearing thresholds by damaging the cochlea through hair cell damage and the excitotoxic, excessive release of glutamate at the hair cell afferent spiral ganglion neuron (SGN) synapse. This excitotoxicity results in the loss of synaptic innervation of the neuron from the hair cell. In somatosensory neurons a similar axotomy results in altered voltage-gated sodium channel (Nav) expression. This study investigates whether similar changes in Nav expression occur in rat SGN following noise exposure. This study has shown the expression of Nav1.1, 1.6 and 1.7 in normal rat SGN using RT-PCR and immunohistochemistry. The noise exposure protocol, 2 sessions presenting a single tone (14.8kHz) at a modest 110dB SPL for 2 hours with 48 hours between each session, resulted with elevated hearing thresholds of the sound-exposed rats of 18±4dB and 24±3dB at 24kHz and 30kHz respectively, with insignificant elevation at frequencies below 16kHz. RT-PCR showed no additional Nav isoforms present in the sound-exposed cochlea. Quantitative PCR showed a significant decrease in Nav1.6 mRNA expression level, reduced by 56% compared to normal hearing animals. Nav1.1 mRNA was significantly reduced by 29% and Nav1.7 mRNA was elevated by 20% when compared to control cochleae. Immunohistochemistry of sound-exposed cochleae showed increased Nav1.1 staining along the peripheral processes of the SGN. Also, staining for Nav1.7 in the SGN was altered in sound-exposed rats compared to control animals, with the majority of sound-exposed animals showing an increase in darker stained neurons. Nav1.6 SGN cell body staining was not altered between sound-exposed and control neurons using immunohistochemistry. SGN cell body counting showed no decrease in neuronal number following sound exposure compared to control cochleae. These results show that Nav expression in rat SGN alters following sound exposure, which may modify neuronal function in deafened animals.
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Bertram, Sebastian Johannes [Verfasser], Stefan [Gutachter] Dazert, and Dominik [Gutachter] Brors. "Einfluss von Pleiotrophin auf das Wachstumsverhalten von Spiral Ganglion Neuronen / Sebastian Johannes Bertram ; Gutachter: Stefan Dazert, Dominik Brors ; Medizinische Fakultät." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/1216332975/34.
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Ishikawa, Masaaki. "Transplantation of neurons derived from human iPS cells cultured on collagen matrix into guinea-pig cochleae." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225472.
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Souchal, Marion. "Surdités cachées ; atteinte des cellules sensorielles cochléaires ou du nerf auditif ?" Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAS003/document.
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Les surdités neurosensorielles sont classiquement décrites par une élévation des seuils auditifs généralement corrélée à une dégénérescence des cellules ciliées externes (CCE). Toutefois, des travaux récents sur des modèles animaux ont montré qu’un audiogramme normal pouvait être associé à des atteintes auditives périphériques. Ce travail de thèse a contribué à mieux caractériser chez des modèles murins, ces déficiences supraliminaires cachées liées d’une part, à des altérations des CCE et d’autre part, à la dégénérescence de certaines fibres nerveuses auditives. Dans la première partie de cette thèse, l’évolution des profils auditifs de souris présentant une dégénérescence accélérée des CCE, les souris de souche CD1-RjOrl : SWISS, a été caractérisée. Dans cette étude longitudinale, menée au cours du premier mois postnatal, une progressivité de la déficience auditive a été montrée. Toutefois, une discordance surprenante a été mise en évidence entre des seuils auditifs proches des valeurs normales à haute fréquence combinés à des produits de distorsions acoustiques (PDA) absents. Les courbes d’accord de masquage montrent un décalage des pointes vers les basses fréquences. Ces données indiquent que les CCE de la base ne sont plus fonctionnelles et que la perception des hautes fréquences est perturbée. Les observations en microscopie électronique à balayage ont révélé une conformation anormale de la touffe stéréociliaire des CCE au niveau de la base de la cochlée. Ces données témoignent d’une désorganisation de la tonotopie cochléaire. Dans la deuxième partie de cette thèse, l’effet de l’oxaliplatine sur la fonction auditive et sur la morphologie cochléaire a été décrit chez des souris adultes de souche CBA/J. L’oxaliplatine, un sel de platine utilisé en chimiothérapie, a de nombreux effets secondaires parmi lesquels l’apparition d’une neuropathie périphérique. À la suite d’un traitement avec cette drogue, les souris ne présentent pas d’élévation des seuils auditifs et pas d’altération de la fonction des CCE. Cependant, l’étude histologique révèle une dégénérescence surprenante des fibres auditives du ganglion spiral. Avec des tests électrophysiologiques supplémentaires, une diminution de l’amplitude du potentiel d’action composite a été mise en évidence. Le réflexe du système efférent olivocochléaire médian, évalué par un test de suppression controlatéral, semble également être diminué par le traitement. Les souris traitées avec de l’oxaliplatine constituent donc un modèle animal précieux de surdité cachée, qui demande à être mieux caractérisé. Les résultats de ces études confirment l’insuffisance de l’audiogramme pour détecter des altérations subtiles de la cochlée et montrent la nécessité d’améliorer le diagnostic de ces déficiences supraliminaires. Ainsi, les atteintes cachées des CCE peuvent être détectées par l’absence de PDA associée à des potentiels évoqués auditifs normaux et les neuropathies par des PDA présents associés à des potentiels évoqués auditifs anormaux. La combinaison de ces différents tests fonctionnels et électrophysiologiques permettrait une meilleure prise en charge des patients et une amélioration de leur qualité de vieSensorineural hearing loss are classically described by auditory thresholds elevation usually correlated with outer hair cells (OHC) degeneration. However, recent work on animal models has shown that normal audiogram can be associated with peripheral hearing impairments. This thesis contributed to better characterize, in mouse models, these hidden supraliminal deficiencies related on the one hand, with OHC alterations and on the other, to auditory nerve fibers degeneration. In the first part of this thesis, the auditory profiles evolution of mice exhibiting an OHC accelerated degeneration, the CD1-RjOrl: SWISS strain mice, was characterized. In this longitudinal study, conducted in the first postnatal month, a progressivity of the hearing impairment has been observed. However, a surprising discrepancy was found between high frequency hearing thresholds close to normal values associated with missing distortion product otoacoustic emission (DPOAE). The masking tuning curves dips are shifted toward low frequencies. Those data indicate that basal OHC are no longer functional and the perception of high frequencies is disrupted. Observations in scanning electron microscopy revealed an abnormal conformation of the OHC stereocilia bundles at the cochlea base. These results represent an evidence of a disorganized cochlear tonotopy. In the second part of this thesis, the effect of oxaliplatin on the auditory function and on the cochlear morphology was described in adult CBA/J strain mice. Oxaliplatin, a platinum salt used in chemotherapy, has many side effects including development of peripheral neuropathy. Following one treatment with this drug, mice did not present any hearing threshold elevation or OHC function impairment. However, the histological study reveals a surprising degeneration of the spiral ganglion cells. With additional electrophysiological tests, a decrease in the compound action potential amplitude has been demonstrated. The median olivocochlear efferent system reflex, evaluated by a contralateral suppression test, also seems to be diminished by the treatment. The mice treated with oxaliplatin, therefore constitute a precious animal model of hidden deafness, which needs to be better characterized. The results of these studies confirm the audiogram insufficiency to detect subtle cochlea alterations and reveal the need to improve supraliminal deficiencies diagnosis. Thus, hidden OHC impairments can be detected by the absence of DPOAE associated with normal auditory evoked potentials and neuropathies by the presence of DPOAE associated with abnormal auditory evoked potentials. The combination of these functional and electrophysiological tests would allow better management of patients and an improvement in their quality of life.Keywords: hidden hearing loss, CD1 mice, outer hair cells, masking tuning curves, tonotopy, oxaliplatine, spiral
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Stephani, Friederike Lene Brigitte [Verfasser]. "α2δ3 is the preferred auxiliary α2δ subunit of Cav2.1 channels in spiral ganglion neurons and is required for development of auditory nerve fiber synapses / Friederike Lene Brigitte Stephani." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1216877823/34.
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Sensor, Jennifer Dawn. "HEARING AND AGE ESTIMATION IN TWO SPECIES OF ARCTIC WHALE." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1512125887991219.
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Rakowicz, Wojciech Piotr. "The regulation of death in retinal ganglion cells and spinal motor neurons." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621305.
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Kleef, Maarten van. "Radiofrequency lesions of the dorsal root ganglion in the treatment of spinal pain." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1996. http://arno.unimaas.nl/show.cgi?fid=6271.
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Cui, Jian-Guo. "Spinal cord stimulation in neuropathy : experimental studies of biochemistry and behaviour /." Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3525-4/.
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Rydh-Rinder, Malin. "Studies on pain-related messengers and receptors in dorsal root ganglia and spinal cord /." Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4553-5/.
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Shi, Tie-Jun. "Regulation of signaling molecules in sensory neurons and spinal cord : studies on nerve injury models and transgenic mice /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4837-2/.
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Chui, Sze-wai. "The influences of intrinsic and extrinsic factors on the axonal regeneration of embryonic and adult dorsal root ganglion neurons : a cryoculture study /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19909196.
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徐思慧 and Sze-wai Chui. "The influences of intrinsic and extrinsic factors on the axonal regeneration of embryonic and adult dorsal root ganglion neurons: a cryoculture study." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31215208.
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Durand, Béatrice. "Lesion iatrogene du nerf spinal apres biopsie ganglionnaire : a propos de 11 cas." Bordeaux 2, 1988. http://www.theses.fr/1988BOR25442.
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Gormley, Ann Marie. "Transgenic approaches to studying the development of sensory and spinal cord neurons." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244742.
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Josephson, Anna. "Spinal cord injury: mechanical and molecular aspects /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-235-3/.
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Maak, Travis Gardner. "Dynamic Intervertebral Foramen Narrowing During Whiplash." Yale University, 2006. http://ymtdl.med.yale.edu/theses/available/etd-06282006-113354/.
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A biomechanical study of intervertebral foraminal narrowing during simulated automotive head-forward and head-turned rear impacts. The objective of this study was to quantify foraminal width, height and area narrowing during head-forward and head-turned rear impacts, and evaluate the potential for nerve root and ganglion impingement. Muscle weakness and paresthesias, documented in whiplash patients, have been associated with neural compression within the cervical intervertebral foramen. Rotated head posture at the time of rear impact has been correlated with increased frequency and severity of chronic radicular symptoms, as compared to facing forward. No studies have quantified dynamic changes in foramen dimensions during head-forward or head-turned rear impacts. Six whole cervical spine specimens with muscle force replication and surrogate head underwent simulated whiplash at 3.5, 5, 6.5 and 8 g, following non-injurious baseline 2 g acceleration. Continuous dynamic foraminal width, height and area narrowing were recorded, and the peaks were determined during each impact and statistically compared to baseline narrowing. During head-forward rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline were observed at C5-C6 beginning with 3.5 g impact. No significant increases in average peak foraminal height narrowing were observed, while average peak foraminal areas were significantly narrower than baseline at C4-C5 at 3.5, 5 and 6.5 g. During head-turned rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline of up to 1.8 mm in the left C5-C6 foramen at 8 g were observed. Average peak dynamic foraminal height was significantly narrower than baseline at right C2-C3 foramen at 5 g and 6.5 g, while no significant increases in foraminal area were observed. Extrapolation of the present head-forward rear impact results indicated that the greatest potential for ganglia compression injury was at the lower cervical spine, C5-C6 and C6-C7. The present head-turned rear impact results indicated that the greatest potential ganglia compression injury exists at C5-C6 and C6-C7. Greater potential for ganglia compression injury exists at C3-C4 and C4-C5 due to head-turned rear impact, as compared to head-forward rear impact. Acute ganglia compression may produce a sensitized neural response to repeat compression leading to chronic radiculopathy following head-forward and head-turned rear impacts. Dynamic ganglion or nerve root compression may also lead to chronic radiculopathy.
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Groth, Michael. "Zur Pleura projizierende Spinalganglienneurone exprimieren pH-sensitive Ionenkanäle : eine Tracingstudie /." Giessen : VVB Laufersweiler, 2007. http://d-nb.info/988755807/34.
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Lüscher, Christian. "Action potential propagation through embryonic dorsal root ganglion cells in a slice culture of the spinal cord of the rat /." [S.l.] : [s.n.], 1993. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Pan-Montojo, Francisco, Oleg Anichtchik, Yanina Dening, Lilla Knels, Stefan Pursche, Roland Jung, Sandra Jackson, et al. "Progression of Parkinson's Disease Pathology is Reproduced by Intragastric Administration of Rotenone in Mice." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-185435.
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In patients with Parkinson's disease (PD), the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS), the dorsal motor nucleus of the vagus (DMV), the intermediolateral nucleus of the spinal cord and the substantia nigra, providing the basis for the neuropathological staging of the disease. Here we report that intragastrically administered rotenone, a commonly used pesticide that inhibits Complex I of the mitochondrial respiratory chain, is able to reproduce PD pathological staging as found in patients. Our results show that low doses of chronically and intragastrically administered rotenone induce alpha-synuclein accumulation in all the above-mentioned nervous system structures of wild-type mice. Moreover, we also observed inflammation and alpha-synuclein phosphorylation in the ENS and DMV. HPLC analysis showed no rotenone levels in the systemic blood or the central nervous system (detection limit [rotenone]<20 nM) and mitochondrial Complex I measurements showed no systemic Complex I inhibition after 1.5 months of treatment. These alterations are sequential, appearing only in synaptically connected nervous structures, treatment time-dependent and accompanied by inflammatory signs and motor dysfunctions. These results strongly suggest that the local effect of pesticides on the ENS might be sufficient to induce PD-like progression and to reproduce the neuroanatomical and neurochemical features of PD staging. It provides new insight into how environmental factors could trigger PD and suggests a transsynaptic mechanism by which PD might spread throughout the central nervous system.
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Merighi, Adalberto. "Light and electron microscopical studies on the distribution of peptides and 'classical' neurotransmitters in dorsal root ganglion cells and in the dorsal horn of the spinal cord." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46446.
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Pan-Montojo, Francisco, Oleg Anichtchik, Yanina Dening, Lilla Knels, Stefan Pursche, Roland Jung, Sandra Jackson, et al. "Progression of Parkinson's Disease Pathology is Reproduced by Intragastric Administration of Rotenone in Mice." PloS ONE, 2010. https://tud.qucosa.de/id/qucosa%3A29010.
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In patients with Parkinson's disease (PD), the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS), the dorsal motor nucleus of the vagus (DMV), the intermediolateral nucleus of the spinal cord and the substantia nigra, providing the basis for the neuropathological staging of the disease. Here we report that intragastrically administered rotenone, a commonly used pesticide that inhibits Complex I of the mitochondrial respiratory chain, is able to reproduce PD pathological staging as found in patients. Our results show that low doses of chronically and intragastrically administered rotenone induce alpha-synuclein accumulation in all the above-mentioned nervous system structures of wild-type mice. Moreover, we also observed inflammation and alpha-synuclein phosphorylation in the ENS and DMV. HPLC analysis showed no rotenone levels in the systemic blood or the central nervous system (detection limit [rotenone]<20 nM) and mitochondrial Complex I measurements showed no systemic Complex I inhibition after 1.5 months of treatment. These alterations are sequential, appearing only in synaptically connected nervous structures, treatment time-dependent and accompanied by inflammatory signs and motor dysfunctions. These results strongly suggest that the local effect of pesticides on the ENS might be sufficient to induce PD-like progression and to reproduce the neuroanatomical and neurochemical features of PD staging. It provides new insight into how environmental factors could trigger PD and suggests a transsynaptic mechanism by which PD might spread throughout the central nervous system.
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McCartney, Annemarie McMillan. "Growth Factors Involved in the Regulation of Neurons and Glial Cells in the Rat Spinal Cord." Miami University Honors Theses / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1178310678.
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Backström, Eva. "Expression of stimulatory and inhibitory molecules in interactions between natural killer cells and neurons /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-516-6.
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Armstrong, Michael G. "Effect of zymosan-induced peritonitis on the expression of substance P in primary sensory neurons and spinal nerve processes." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/honors/328.
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Macrophages and other cells of the innate immune system recognize foreign particles that could be potentially dangerous and respond by initiating an inflammatory response. The biologically active chemical mediators of this response called pro-inflammatory cytokines are produced in various myeloid derived immune cells and can affect other cells of the body. Interleukin-1β, a pro-inflammatory cytokine, has been shown to have direct effects on dorsal root ganglion (DRG) cell bodies including the upregulation and direct release of a nociceptive neurotransmitter called substance P (SP). Using a zymosan-induced model of systemic inflammation, we hypothesized that murine DRG neurons and the nerve processes associated with them in the dorsal horn of the spinal cord (SC) at the L1 level will show an upregulation of SP expression in response to inflammation in the peritoneum. Experimental mice were treated with a zymosan suspension (500mg/kg, intraperitoneal injection), and control mice received sterile filtered solution (intraperitoneal injection). Both DRG and SC specimens were collected after in situ fixation and subjected to immunofluorescence staining to label SP. Using confocal microscopy, fluorescence microscopy, and image analysis software this expression of SP was quantified and compared. In both tissue specimen groups, an increase in SP expression was discovered in zymosan treated mice. The exact cause of this increase was not specifically determined in this experiment. This experiment provided valuable insight about how a systemic inflammatory response can affect sensory nerve function. Successful methods for further experimentation were identified and information about the zymosan model of inflammation was obtained
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Mille-Hamard, Laurence. "Transplantation de ganglions rachidiens fœtaux et adultes dans la moelle épinière et dans le nerf péronier du rat adulte : survie, expression phénotypique et capacité de repousse axonale des neurones sensoriels primaires qui y sont contenus." Paris 5, 1997. http://www.theses.fr/1997PA05S031.
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Apres lésion traumatique de la moelle épinière, une restructuration médullaire complète nécessite non seulement le rétablissement du versant efférent, moteur, mais aussi de celui du versant affèrent, sensitif. Dans une approche de recherche fondamentale susceptible de s'ouvrir sur des perspectives cliniques, nous avons transplante, chez le rat adulte, des ganglions rachidiens cervicaux fœtaux et adultes : 1) dans le nerf péronier ; 2) dans la moelle épinière cervicale. Dans le cas des seules transplantations intramédullaires de ganglions adultes, nous avons réalisé trois variantes : a) ganglion(s) seul(s) ; b) ganglion connectée à un autogreffon de nerf périphérique (gnp) ; c) ganglion relie, au moyen d'un gnp, a un muscle squelettique préalablement dénervé. Chez le rat adulte, nous avons estimé à 7000 le nombre de neurones sensoriels primaires dans les ganglions rachidiens cervicaux 4, 5 et 6. Transplantes dans le système nerveux périphérique, 20% de ces neurones survivent. Dans la moelle épinière, les ganglions sont biens tolérés, mais seuls 5% des neurones sensoriels primaires survivent à la transplantation, leurs caractéristiques phénotypiques sont modifiées. La présence d'éléments nerveux périphériques permet la survie d'un plus grand nombre de neurones, en particulier ceux de plus grand diamètre. De façon surprenante, la survie des neurones sensoriels primaires fœtaux est inférieure à celle des neurones adultes. Les neurones sensoriels primaires fœtaux et adultes transplantes sont capables de régénérer, et certains de façon bidirectionnelle, dans le système nerveux périphérique. On en conclut que les neurones sensoriels primaires des ganglions rachidiens, tant adultes que fœtaux, peuvent être transplantes dans le système nerveux central et dans le système nerveux périphérique du rat adulte. Dans une perspective thérapeutique de réparation médullaire post-traumatique, il conviendrait de préciser le degré d'intégration anatomique et fonctionnelle des transplants et de rechercher de nouvelles stratégies (facteurs neurotrophiques, thérapie génique, etc. ) permettant d'augmenter le taux de survie des neurones sensoriels transplantes.
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Hu, Zhengqing. "Investigating a cell replacement therapy in the inner ear /." Stockholm, 2004. http://diss.kib.ki.se/2005/91-7140-170-9/.
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Cofiño, de Sá Rafael 1980. "Avaliação morfológica e imunoistoquímica do efeito da administração de melatonina sobre neurônios sensoriais dos gânglios da raiz dorsal de ratos neonatos após da seção do nervo ciático." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314228.
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Orientador: Francesco LangoneDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A secção do nervo ciático em ratos neonatos pode induzir morte neuronal no gânglio da raiz dorsal (DRG). A perda neuronal dependeria da idade do animal, da severidade da lesão e do tipo de neurônio acometido (GILLARDON et al, 1996). A morte de neurônios sensoriais submetidos à axotomia poderia envolver a produção de óxido nítrico (NO) e seus derivados (CLOWRY, 1993; YICK et al, 1998). A molécula de NO, por possuir um elétron desemparelhado em seu orbital externo, é um radical livre que pode interagir com diversas moléculas intracelulares, inclusive com outros radicais livres. (DAWSON et al., 1993). No meio intracelular, os radicais livres podem inibir a respiração mitocondrial, causar peroxidação de lípides da membrana celular e induzir apoptose. No presente estudo, ratos com dois de vida (P2) foram submetidos à secção unilateral do ciático e tratados diariamente com o neurohôrmonio antioxidante melatonina durante cinco dias. Nos neurônios dos gânglios L4 e L5 foram avaliados a imunorreatividade e distribuição tecidual das proteínas Bax e Bcl-2, da isoforma neuronal do óxido nítrico sintase (nNOS) e das isoformas 1 e 2 da superóxido dismutase (SOD1 e 2). A análise macroscópica dos gânglios L4 e L5 de ratos submetidos à secção unilateral do nervo ciático em P2 evidenciou diminuição dos gânglios ipsilaterais à axotomia, cinco dias após a lesão. Tal fato sugere atrofia destes últimos em decorrência do estímulo lesivo periférico. A melatonina poderia exercer efeito neuroprotetor sobre neurônios de grande diâmetro nuclear, uma vez que nos animais tratados foram observado aumento da imunomarcação para a proteína antiapoptótica Bcl-2 e para as enzimas anti-oxidantes SOD1 e SOD2. A secção do nervo ciático em ratos neonatos (P2) aumenta a imunorreatividade para nNOS cinco dias após a lesão em neurônios de pequeno diâmetro nuclear, e o tratamento com melatonina não altera este padrão. Os neurônios de pequeno diâmetro nuclear poderiam agir de modo neuroprotetor parácrino aumentando a produção de NO, mas o mecanismo preciso ainda não foi estabelecido
Abstract: Section of sciatic nerve in neonatal rats may induce neuronal death in the dorsal root ganglia (DRG). Neuronal loss would depend on the age of the animal, severity of injury and type of neuron (GILLARDON et al, 1996). Death of sensorial neurons submitted to sciatic transection could involve nitric oxide (NO) production and its derivatives (CLOWRY, 1993; YICK et al, 1998). NO molecule has an unpaired external orbital electron and is considered a free radical. It may interact with various intracellular molecules, including other free radicals. (DAWSON et al., 1993). Inside the cell, free radicals may cause inhibition of mitocondrial respiration, lipid peroxidation of the cellular membrane and induce apoptosis. In the present study, newborn rats (P2) were subjected to unilateral sciatic nerve transection and received daily treatment with antioxidant melatonin from P2 to P7. Imunohistochemical detection and tissue distribution of Bax and Bcl-2; neuronal isoform of nitric oxide sintase (nNOS); and of superoxide dismutase isoforms 1 and 2 (SOD1 and 2) in L4 and L5 DRG neurons were evaluated. Macroscopic analysis of L4 and L5 DRG on rats submitted to sciatic nerve unilateral transection at P2 evidenced reduction on same side lesion ganglia, five days after injury. Such fact suggests atrophy of DRG as a result of peripheral harmful stimulus. Melatonin could exert neuroprotective effect on large nuclear diameter neurons, since treated animals increased immunostaining for anti-apoptotic protein Bcl-2 and antioxidant enzymes SOD1 and SOD2. Transection of sciatic nerve in newborn rats (P2) increases immunostaining for nNOS in small nuclear diameter neurons five days after lesion injury, and treatment with melatonin does not alter this pattern. Small nuclear diameter neurons could act in paracrine fashion increasing NO production, but specific mechanism remains unclear
Mestrado
Fisiologia
Mestre em Biologia Celular e Estrutural
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Gannon, Sean Michael. "Plasticity in the intermediolateral cell column of the spinal cord following injury to sympathetic postganglionic axons." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1407112137.
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Melo, Edgard Julian Osuna. "Expressão de conexina 36 e conexina 43 em células do gânglio da raiz dorsal e seu envolvimento na nocicepção." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42136/tde-11062014-165139/.
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Os canais de junções comunicantes (gap junctions, JC) são formados por subunidades chamadas de conexinas (Cx). Estas proteínas têm papel relevante no acoplamento celular, participando da condutância de células nervosas ou gliais e modulando vários processos fisiológicos e fisiopatológicos. O objetivo deste trabalho é avaliar o envolvimento das conexinas na nocicepção aguda, por meio de ensaios comportamentais e estudos de mapeamento da sua expressão em células do gânglio da raiz dorsal de ratos. Para tanto, foi analisado o efeito de carbenoxolone (CBX) e quinina (bloqueadores de JCs), assim como de oligonucleotídeos antisense para conexinas 36 e 43 na indução e manutenção de hiperalgesia induzida por carragenina em ratos. Os resultados mostraram que a carragenina induz uma diminuição do limiar nociceptivo em ratos e que esse efeito hiperalgésico da carragenina foi bloqueado pelo tratamento com carbenoxolone (nas doses 20-50mg) e significantemente inibido por quinina (nas doses 20-50mg), sugerindo uma participação das junções comunicantes (JC) no processo.Gap junctions channels (GJ) are formed by proteic subunits called connexins (Cx). These proteins have an important role in cellular coupling, participating in the conductance of glial and nerve cells or modulating various physiological and pathophysiological processes. The aim of this study is to evaluate Cx36 and Cx43 involvement in acute nociception through behavioral assays, mapping studies of its expression in rat dorsal root ganglion cells. For this purpose, we analyzed the effect of intrathecal treatment with carbenoxolone (CBX) and quinine (GJs blockers), as well as antisense oligonucleotides for connexins 36 and 43 in the induction and maintenance of carrageenan-induced hyperalgesia in rats. The results show that carrageenan induces a nociceptive threshold decrease in rats. The hyperalgesic effect was blocked by treatment with carbenoxolone (20-50mg doses), Cx43 antisense and inhibited significantly by quinine (at doses 20 -50mg) but no with Cx36 antisense, suggesting an involvement of gap junctions (JC) in the process.
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Custódio, Augusto Henrique 1983. "Estudo da denervação renal bilateral e da imunorreatividade para substância P (SP), CGRP e receptor 1 para neurocinina (NK1R) no gânglio da raiz dorsal e parede pélvica renal na prole de ratas submetidas a restrição proteica gestacional." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/312740.
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Orientador: Jose Antonio Rocha GontijoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: A programação fetal é um processo fisiológico que assegura, durante o desenvolvimento intrauterino, a adaptação para o mundo exterior. Ou seja, o organismo é "moldável" por estímulos durante sua formação e dependendo do insulto experimentado, existe a possibilidade de mudanças estruturais e funcionais que podem predispor o indivíduo a doenças na vida adulta. O modelo de restrição proteica, assim como outros modelos, leva a um "stress" gestacional e, segundo a hipótese de Barker, programa a prole ao desenvolvimento de doenças na vida adulta, dentre elas a hipertensão arterial. Os rins são órgãos fundamentais na manutenção do equilíbrio hemodinâmico. Mudanças morfológicas e neuroendócrinas nos rins levam a alterações hidroeletrolíticas frequentemente associadas à patogênese da hipertensão arterial. A gênese desta doença ainda não está bem descrita, por envolver alterações multifatoriais, dentre elas, modificações da atividade neural tanto central quanto periférica, que podem ser um indicativo da elevação pressórica em nosso modelo. A atividade simpática renal é um importante modulador da excreção dos eletrólitos e, quando alterada, promove maior ou menor retenção de sais, principalmente o sódio, podendo contribuir para a elevação da volemia e consequentemente da hipertensão arterial. Diversos neuropeptídeos estão envolvidos na atividade simpática renal e os níveis destes são um importante marcador na gênese da hipertensão. Dentre esses peptídeos estão a Substância P (SP), seu receptor NK1R e o Peptídeo Relacionado ao Gene da Calcitonina (CGRP). Nossos resultados mostraram redução na imunorreatividade de SP, CGRP e aumento do receptor 1 para neurocinina nos gânglios da raiz dorsal da prole de ratas submetidas à restrição proteica gestacional. Identificamos também a elevação dos níveis de CGRP na parede pélvica renal. Assim, acreditamos que haja alterações na neuromodulação da atividade aferente renal, o que pode ser um fator contribuinte para a manutenção do estado hipertensivo neste modelo experimental
Abstract: A fetal programming is a physiologic process that ensures an adaptation for external world during the intra uterine development. In this period, the organism is "moldable" by stimulus that happens during its formation, which ensures adequate phenotypes formation for different environments. Kidneys are the most important organs when it has to do with maintaining the organism hemodynamic balance and also morphological and neuroendocrine alterations, which leads to fluid and eletrolytes changes, frequently associated to arterial hypertension pathogenesis. The genesis of this disease is not well described yet. It involves multifactorial changes like the neural activity in both central as peripheral, which, in our model, may be an indicative of increased pressure. The renal sympathetic activity is an important excretion modulator of electrolytes and when amended, promotes greater or lesser retention of salts, mainly sodium, contributing to the increase in blood volume and consequently hypertension. Several neuropeptides are involved in renal sympathetic activity, and these levels are an important marker in the genesis of hypertension. Among these peptides we find substance P (SP) and its receptor NK1R, and Related Peptide Calcitonin Gene (CGRP). Our research showed reduced immunoreactivity of SP, CGRP and increased neurokinin 1 receptor in dorsal root ganglia among the offspring of rats subjected to gestational protein restriction. According to this result, we believe that there are changes in afferent renal activity neuromodulation which may be a contributing factor for maintenance of hypertension in this experimental model
Mestrado
Medicina Experimental
Mestre em Ciências
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Welin, Dag. "Neuroprotection and axonal regeneration after peripheral nerve injury." Doctoral thesis, Umeå : Umeå university, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-32819.
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Brown, Todd J. "The effects of axotomy or castration on microglia in pudendal nerve motor nuclei and pudendal sensory areas as well as effects on pudendal primary afferents in the rat spinal cord and dorsal root ganglia /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487935573772179.
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Schlichter, Rémy. "Etude de la distribution et des proprietes pharmacologiques des recepteurs du gaba sur les afferences primaires du rat." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13089.
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Etude electrophysiologique intracellulaire par courant et potentiel imposes de la distribution et des proprietes pharmacologiques de deux types de recepteur gabaerique a et b sur les afferences primaires (ab, ad et c) d'une preparation "in vitro" de ganglion rachidien de rat adulte
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Gatto, Cheryl Lynn. "Novel Insights into Schwann Cell Dynamics in Peripheral Nervous System Myelination: a dissertation." eScholarship@UMMS, 2004. https://escholarship.umassmed.edu/gsbs_diss/213.
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This body of work details the exploitation of an incredibly powerful neural culture system, which enables the in vitrostudy of events involved in peripheral nervous system (PNS) development. Using a myelinating dorsal root ganglion (DRG) explant culture system, node of Ranvier formation and maintenance and the associated generation and maturation of myelin segments was examined. In addition, Schwann cell (SC) development, dynamics, and migration were extensively studied.
First, in characterizing these cultures, the discrete axonal localization of specific ankyrin isoforms was revealed. Ankyrins are peripheral membrane proteins that immobilize classes of integral membrane proteins to the spectrin based-membrane skeleton. Ankyrins interact with proteins such as the voltage-dependent/gated sodium channel (vgsc) and members of the L1 family of cell adhesion molecules. These interactions are physiologically relevant to the formation of membrane specializations involved in axon guidance and the initiation and propagation of action potentials.
We examined ankyrinB and ankyrinG expression in cultured DRG explants, which allowed visualization of individual axons. AnkyrinB and ankyrinG exhibited differential localizations to specific axonal populations. This was evident as early as one day in vitro and persisted over time. In mature pre-myelinated cultures, axons having an apparent diameter of less than 1 µm predominantly expressed ankyrinB, whereas axons having a diameter greater than or equal to 1 µm predominantly expressed ankyrinG (based on immunocytochemical reactivity). When myelination was induced, ankyrinGwas appropriately localized to sites of nodal development flanked by myelinating glial processes in the large caliber axons. These observations suggest that axons destined for myelination may express a distinct complement of peripheral, and perhaps integral, membrane proteins as compared to those observed in non-myelinated axons. These distinguishing features may play a role in the selection of axons for myelination.
This work was followed with defining the role axo-glial interactions play in organizing domains along the axon being myelinated. Nodes of Ranvier are specialized, highly polarized axonal domains crucial to the propagation of saltatory action potentials. In the PNS, axon-glial cell contacts have been implicated in SC differentiation and the formation of nodes of Ranvier. SC microvilli establish axonal contact at mature nodes, and their components have been observed to localize early to sites of developing nodes. However, a role for these contacts in node formation remains controversial.
Using the myelinating explant culture system, we observed that SCs reorganize and polarize microvillar components, such as the ezrin-binding phosphoprotein 50kDa (EBP50)/regulatory co-factor of the sodium-hydrogen exchanger isoform 3 (NHERF-1), actin, and the activated ezrin, radixin, and moesin (ERM) family of proteins, concomitant with myelination in response to inductive signals. These components were targeted to the SC distal tips where live cell imaging revealed novel, dynamic growth cone-like behavior. Further, localized activation of the Rho signaling pathway at SC tips gave rise to these microvillar component-enriched “caps” and influenced the efficiency of node formation.
Extending these findings, a more profound examination of SC dynamics was undertaken. This was a particularly important experimental transition, as SC motility is crucial in the development and regeneration of the PNS. The seemingly equivalent bipolarity of mature SCs represents a conundrum in terms of directed motility. Fluorescence time-lapse microscopy of transfected SCs within the myelinating DRG explants revealed a novel cycling of these cells between static, bipolar and motile, unipolar morphologies via asymmetric process retraction and extension. Concentrations of PIP2 (phosphatidylinositol (4,5)-bisphosphate), activated ERMs, and EBP50 delineated the transitory asymmetry associated with the generation and neuron-like migration of the unipolar cell. EBP50 over-expression enhanced unipolar SC migration, suggesting a new role for this adaptor protein in cell motility. Further, the ERMs themselves were found to be essential to both motility and process dynamics with ERM disruption yielding a dysfunctional, multipolar SC phenotype. We propose this novel form of motility may be associated with the correct alignment and spacing of SCs along axons prior to elaboration of the myelin sheath.
These compiled studies present significant advances in understanding and examining axo-glial interactions in the PNS. This work establishes the foundation for further, novel exploration of normal PNS development and the regeneration and repair mechanisms involved in PNS injury and disease states.
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Lara-Ramirez, Ricardo. "Lamprey neural Helix-Loop-Helix (HLH) genes and the evolution of the vertebrate nervous system." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:107e31ad-9183-4b07-842b-d01e27a4c9e6.
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Transcription factors of the helix-loop-helix (HLH) gene family are widespread in the animal kingdom. Among them, members of HLH subfamilies such as ASCL, Neurogenin, NeuroD, COE, Atonal, Oligo, NSCL, Hairy/E(spl) and Hey (here referred to as neural HLH genes) have been shown to be fundamental for the development of the nervous system. They are expressed at different time periods of neuronal differentiation, from the specification of ectoderm towards a neural lineage, to the ultimate differentiation of neurons. Few HLH genes have been identified in the lamprey; however, considering the wide diversity of HLH gene subfamilies in metazoans, including vertebrates, it is very likely that lampreys possess a large repertoire of HLH genes in their genome. In the present study, the identification of several HLH genes in the lamprey genome, as well as the isolation and expression of different lamprey neural HLH genes is reported. As expected, a wide repertoire of HLH genes was identified in the sea lamprey (Petromyzon marinus) genome. On the other hand, the identification and expression analysis of different neural HLH genes of the ASCL, Neurogenin, COE and Hairy/E(spl) in the brook lamprey Lampetra planeri showed an overall conservation with other vertebrates, both at the sequence and expression pattern levels. In addition, novel features of the lamprey nervous system are revealed, such as the identification of possible new sensory cranial placodes in pharyngeal arches. Furthermore, these genes can serve as molecular markers for different cranial placodes and dorsal root ganglia (DRG), and their expression also highlights the presence of a ventricular zone in the brain and spinal cord, along with a complementary marginal zone. Finally, with the use of a Notch pathway inhibitor in developing L. planeri embryos, the regulation of expression of the isolated genes by the Notch signaling pathway was shown to be generally conserved between lampreys and gnathostomes in the spinal cord. This functional study also revealed that the lamprey spinal cord likely presents an independent developmental programme from the brain. All together, the present study shows that the analysis of neural HLH genes represents an excellent tool to understand the lamprey nervous system.
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Manns, Richard Peter Charles. "Repulsive cues and signalling cascades of the axon growth cone." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/245741.
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The aim of the work described in this thesis is to investigate the nature and mechanisms of action of repellent cues for growing axons. In particular I try to resolve the controversy in the literature regarding the need for protein synthesis in the growth cone in response to external guidance cues. My results resolve the conflicting data in the literature on Semaphorin-3A signalling, where differing labs had shown that inhibiting protein synthesis either blocks or has no effect upon repulsion. They demonstrate the presence of at least two independent pathways, protein synthesis-dependent mTOR activation and -independent GSK3? activation. The higher sensitivity of the synthesis-dependent pathway, and its redundancy at higher concentrations where synthesis-independent mechanisms can evoke a full collapse response alone, resolve the apparent conflict. My experiments also demonstrated that Nogo-?20, a domain of Nogo-A, requires local protein synthesis to cause collapse. Unlike Semaphorin-3A, the dependence of collapse upon protein synthesis is concentration-independent and does not involve guanylyl cyclase, but it does share a dependence upon mTOR activity and the synthesis of RhoA, sufficient to cause collapse downstream of Semaphorin-3A. The other axon-repelling domain of Nogo-A, Nogo-66, is partially dependent upon the proteasome instead. It does not share a common pathway with Nogo-?20, except that both are RhoA-dependent. I further attempted to identify the nature of a repulsive activity found in grey matter, ruling out a previously suggested candidate identity. Finally, I examined the phenomenon of nitric oxide-induced growth cone collapse. My experiments revealed that S-nitrosylated glutathione causes growth cone collapse through the activity of protein disulphide isomerase. This mechanism shows only a partial dependence upon soluble guanylyl cyclase, but I argue that it has total dependence upon an S-nitrosylated donor. Coupled with its apparent relation to S-palmitoylation, the reciprocal of S-nitrosylation, I propose that nitric oxide causes collapse by crossing the cell membrane to inhibit S-palmitoylation-determined localisation of proteins. These results reveal some of the many pathways involved in growth cone collapse, whose further characterisation may provide new targets for the treatment of injuries of the central nervous system.
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Rhrich-Haddout, Fatiha. "Greffe de tissu nerveux fœtal homotypique et hétérotypique dans la moelle épinière du rat adulte après lésion traumatique expérimentale : étude morphologique et immunocytochimique de la différenciation des neurones transplantes." Paris 5, 1993. http://www.theses.fr/1993PA05CD08.
Full textAbstract:
Nous avons étudié la différenciation neuronale dans les greffons de tissu nerveux fœtal homotypique (moelle épinière) ou hétérotypique (néocortext, ganglions rachidiens) non dissocié, après transplantation dans une cavité faite par aspiration dans la moelle épinière cervicale de rats adultes. Cette évolution a été en partie comparée à celle du tube nerveux maintenu in situ, au cours du développement normal. Dans ce but, nous avons mis en œuvre des techniques principalement immunocytochimiques utilisant des anticorps dirigés soit contre des éléments structuraux du neurone ou de la fibre nerveuse (neurofilaments = NF, périphérine = P, protéine basique de la myéline = MBP), soit contre des molécules impliquées dans la transmission synaptique (calcitonin gene-related peptide = CGRP, choline acétyl-transférase = ChAT, gamma amino-butyric acid = GABA, tyrosine hydroxylase = TH). A titre de complément, une étude délibérément restreinte de l'ultrastructure des seuls transplants de moelle épinière fœtale a été également entreprise. Les trois types de greffons survivent à la transplantation tout en s'intégrant aux tissus de l'animal receveur. Bien que l'organisation d'ensemble des transplants reste généralement très atypique, on observe, au niveau cellulaire, un processus systématique de maturation des neurones survivants et de leur environnement neuronal, glial et vasculaire qui présente certains analogies avec le développement normal. Dans les transplants de moelle épinière fœtale, la différenciation neuritique a pu être appréciée par l'immunoréactivité vis-à-vis de l'anticorps anti-NF. Certains de ces neurites sont myélinisés (MBP+). Une immunoréactivité P+, CGRP+ ou ChAT+ et observée au niveau de certains neurones, dispersés dans les transplants. Ces marqueurs sont spécifiques des motoneurones ou des neurones sympathiques préganglionnaires. L'existence d'un système inhibiteur est démontrée par l'immunoréactivité de quelques neurones et de très nombreux boutons vis-à-vis d'un anticorps anti-GABA. L'étude ultrastructurale témoigne de l'existence de nombreuses synapses axo-somatiques et axo-dentritiques, ainsi que du processus de myélinisation des axones par les oligodentrocytes. La maturation astrocytaire est révélée par la présence de faisceaux denses de gliofilaments. Un processus comparable de maturation neuronale est observé dans les transplants de néocortex. Il est mis notamment en évidence par une large immunoréactivité anti-NF, anti-MBP et anti-GABA. L'immunoréactivité anti-CGRP est confinée au niveau des fibres nerveuses qui très probablement d'origine exogène. La présence de neurones catécholaminergiques est démontrée par leur immunoréactivité anti-TH. L'existence de neurones et de fibres immunoréactives pour la périphérine est d'interprétation malaisée. Dans les transplants de ganglions rachidiens, seuls survivent à long terme des neurones sensoriels primaires de petite taille qui sont tous très immunoréactifs pour la périphérine. Une étude comparative de l'immunioréactivité pour la périphérine et pour le CGRP a montré l'existence de nombreux neurones P+/CGRP- et d'un nombre beaucoup plus faible de neurones P+/CGRP+. Les résultats du présent travail démontrent que les différents transplants utilisés sont le siège d'un important processus de maturation neuronale et glio-vasculaire. Ils s'ajoutent à ceux obtenus précédemment par le même groupe de recherche, révélant d'une part d'importantes capacités d'axogenèse )à partir des neurones transplantés et démontrant d'autre part des possibilités de réafférentation des transplants par les fibres nerveuses de l'animal hôte. Ils devront être complétés par des études visant à établir dans quelle mesure les transplants nerveux peuvent être fonctionnellement intégrés dans les circuits sensori-moteurs de l'animal hôte.
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Huang, Jie Green Steven H. "Depolarization-dependent pro-survival signaling in spiral ganglion neurons." 2007. http://ir.uiowa.edu/etd/214.
Full text
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Sun, Wei. "Function of cochlear spiral ganglion neurons and effects of neurotrophic factors on their development." 2006. http://proquest.umi.com/pqdweb?did=1184157381&sid=1&Fmt=2&clientId=39334&RQT=309&VName=PQD.
Full textAbstract:
Thesis (Ph.D.)--State University of New York at Buffalo, 2006.Title from PDF title page (viewed on Mar. 15, 2007) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Salvi, Richard J. Includes bibliographical references.
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Dvořáková, Martina. "Funkční role SOX2 v neurosenzorickém vývoji vnitřního ucha." Doctoral thesis, 2020. http://www.nusl.cz/ntk/nusl-434443.
Full textAbstract:
The main functional cells of the inner ear are neurons and sensory cells that are formed from a common embryonic epithelial neurosensory domain. Discovering genes important for specification and differentiation of sensory cells and neurons in the inner ear is a crucial basis for understanding the pathophysiology of hearing loss. Some of these factors are necessary not only for the inner ear but also for the development of other neurosensory systems such as the visual and olfactory system. The aim of this work was to reveal functions of transcription factor SOX2 in inner ear development by using mouse models with different conditional deletions of Sox2 gene. Sox2 gene was deleted by cre-loxP recombination. In Isl1-cre, Sox2 CKO mutant, reduced number of hair cells differentiated only in some inner ear organs (utricle, saccule and cochlear base) and not in others (cristae and cochlear apex). Early forming inner ear neurons in the vestibular ganglion and neurons innervating the cochlear base developed in these mutants but died by apoptosis due to the lack of neurotrophic support from sensory cells. Late forming neurons in the cochlear apex never formed. In Foxg1-cre, Sox2 CKO mutant, only rudimental ear with no sensory cells was formed. The initial formation of vestibular ganglion with peripheral and...
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"Characterisation of prostacyclin receptors in adult rat dorsal root ganglion cells." 2000. http://library.cuhk.edu.hk/record=b5890465.
Full textAbstract:
Rowlands Dewi Kenneth.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 113-121).
Abstract --- p.i
Acknowledgements --- p.iii
Publications --- p.iv
Abbreviations --- p.v
Contents --- p.vii
Chapter Chapter 1 --- Prostaglandins --- p.1
Chapter 1.1 --- Introduction --- p.1
Chapter 1.2 --- Prostanoid biosynthesis and metabolism --- p.1
Chapter 1.3 --- Prostaglandin receptors --- p.3
Chapter 1.3.1 --- DP-receptors --- p.3
Chapter 1.3.2 --- EP1-receptors --- p.4
Chapter 1.3.3 --- EP2-receptors --- p.4
Chapter 1.3.4 --- EP3-receptors --- p.5
Chapter 1.3.5 --- EP4-receptors --- p.6
Chapter 1.3.6 --- FP-receptors --- p.7
Chapter 1.3.7 --- IP-receptors --- p.8
Chapter 1.3.8 --- TP-receptors --- p.11
Chapter 1.4 --- Agonists and antagonists --- p.11
Chapter Chapter 2 --- Role of prostacyclin in pain modulation --- p.14
Chapter 2.1 --- Pain --- p.14
Chapter 2.2 --- Prostaglandins and pain --- p.15
Chapter 2.3 --- Prostacyclin and pain --- p.16
Chapter 2.3.1 --- [3H]-Iloprost binding sites --- p.16
Chapter 2.3.2 --- IP-receptor mRNA --- p.17
Chapter 2.3.3 --- IP-receptor knockout mice --- p.17
Chapter 2.3.4 --- Direct nociceptive action of prostacyclin --- p.18
Chapter 2.4 --- Treatment of prostanoid-induced pain --- p.19
Chapter Chapter 3 --- Dorsal root ganglion cells --- p.21
Chapter 3.1 --- In vitro model of pain --- p.21
Chapter 3.2 --- Characteristics of cultured DRG cells --- p.22
Chapter 3.2.1 --- Size and distribution --- p.22
Chapter 3.2.2 --- Biochemical and physiological characteristics --- p.22
Chapter 3.2.2.1 --- Gapsaicin-sensitive neurones --- p.23
Chapter 3.2.2.2 --- Neuropeptide content --- p.23
Chapter 3.2.2.3 --- Elevation of [Ca2+］i --- p.24
Chapter 3.3 --- Effect of nerve growth factor --- p.24
Chapter Chapter 4 --- Materials and solutions --- p.26
Chapter 4.1 --- Materials --- p.26
Chapter 4.2 --- Solutions --- p.30
Chapter 4.2.1 --- Culture medium --- p.30
Chapter 4.2.2 --- Buffers --- p.31
Chapter 4.2.3 --- Solutions --- p.32
Chapter Chapter 5 --- Development of dorsal root ganglion cell preparation --- p.33
Chapter 5.1 --- Introduction --- p.33
Chapter 5.2 --- Methods --- p.34
Chapter 5.2.1 --- Dissection of dorsal root ganglia --- p.34
Chapter 5.2.2 --- Preparation of a single-cell suspension --- p.34
Chapter 5.2.2.1 --- Effect of trimming dorsal root ganglia --- p.34
Chapter 5.2.2.2 --- Enzymatic dissociation --- p.35
Chapter 5.2.2.3 --- Mechanical dissociation --- p.36
Chapter 5.2.3 --- Neuronal cell enrichment --- p.36
Chapter 5.2.3.1 --- Differential adhesion --- p.36
Chapter 5.2.3.2 --- BSA gradient --- p.37
Chapter 5.2.3.3 --- Combination of BSA gradient and differential adhesion --- p.37
Chapter 5.2.4 --- Cell counting --- p.37
Chapter 5.2.5 --- Culture conditions --- p.38
Chapter 5.2.6 --- Size distribution of DRG cells --- p.39
Chapter 5.2.7 --- Immunocytochemistry --- p.39
Chapter 5.3 --- Results and discussion --- p.40
Chapter 5.3.1 --- Preparation of single-cell suspension --- p.40
Chapter 5.3.2 --- Neuronal cell enrichment --- p.42
Chapter 5.3.3 --- Size distribution of DRG cells --- p.32
Chapter 5.3.4 --- Effects of mitotic inhibitors and NGF --- p.45
Chapter 5.3.5 --- Immunocytochemistry --- p.48
Chapter 5.4 --- Conclusions --- p.48
Chapter Chapter 6 --- Methods --- p.53
Chapter 6.1 --- Dorsal root ganglion cell preparation --- p.53
Chapter 6.1.1 --- Preparation of tissue culture plates and coverslips --- p.54
Chapter 6.1.2 --- Preparation of Pasteur pipettes --- p.54
Chapter 6.2 --- Measurement of adenylate cyclase activity --- p.55
Chapter 6.2.1 --- Introduction --- p.55
Chapter 6.2.2 --- Preparation of columns --- p.55
Chapter 6.2.3 --- Measurement of [3H]-cyclic AMP production --- p.56
Chapter 6.2.4 --- Data analysis --- p.57
Chapter 6.3 --- Measurement of phospholipase C activity --- p.58
Chapter 6.3.1 --- Introduction --- p.58
Chapter 6.3.2 --- Preparation of columns --- p.58
Chapter 6.3.3 --- Measurement of [3H]-inositol phosphate production --- p.59
Chapter 6.3.4 --- Data analysis --- p.60
Chapter 6.4 --- Measurement of [Ca2+]i --- p.60
Chapter 6.4.1 --- Introduction --- p.60
Chapter 6.4.2 --- Preparations of cells --- p.61
Chapter 6.4.3 --- Measurement of Fura-2 fluorescence --- p.62
Chapter 6.5 --- Measurement of neuropeptides --- p.62
Chapter 6.5.1 --- Introduction --- p.62
Chapter 6.5.2 --- Preparation of cells --- p.63
Chapter 6.5.3 --- CGRP assay --- p.64
Chapter 6.5.4 --- Substance P assay --- p.64
Chapter 6.5.5 --- Purification of samples using Sep-Pak cartridges --- p.65
Chapter Chapter 7 --- Characterisation of prostacyclin receptors on adult rat dorsal root ganglion cells --- p.66
Chapter 7.1 --- Stimulation of adenylate cyclase --- p.66
Chapter 7.1.1 --- Introduction --- p.66
Chapter 7.1.2 --- Agonist concentration-response curves --- p.67
Chapter 7.1.3 --- Cross-desensitisation experiments --- p.72
Chapter 7.1.4 --- Evidence for EP3-receptors --- p.77
Chapter 7.1.5 --- G-protein coupling of the IP-receptor --- p.77
Chapter 7.1.6 --- Discussion --- p.78
Chapter 7.1.7 --- Conclusions --- p.82
Chapter 7.2 --- Stimulation of phospholipase C --- p.82
Chapter 7.2.1 --- Introduction --- p.82
Chapter 7.2.2 --- Agonist concentration-response curves --- p.83
Chapter 7.2.3 --- G-protein coupling --- p.83
Chapter 7.2.4 --- Discussion and Conclusions --- p.84
Chapter 7.3 --- Stimulation of changes in [Ca2+]i --- p.87
Chapter 7.3.1 --- Introduction --- p.87
Chapter 7.3.2 --- Preliminary results --- p.87
Chapter 7.3.3 --- Discussion and conclusions --- p.89
Chapter Chapter 8 --- Neuropeptide release by adult rat dorsal root ganglion cells --- p.90
Chapter 8.1 --- Introduction --- p.90
Chapter 8.2 --- Methods and Results --- p.91
Chapter 8.3 --- Discussion --- p.91
Chapter 8.4 --- Conclusions --- p.92
Chapter Chapter 9 --- Regulation of prostacyclin receptors on adult rat DRG cells --- p.93
Chapter 9.1 --- Introduction --- p.93
Chapter 9.2 --- Contribution of non-neuronal cells --- p.93
Chapter 9.3 --- Effect of DRG cell density --- p.94
Chapter 9.4 --- Effect of indomethacin --- p.99
Chapter 9.5 --- Contribution of endogenously-produced non-prostanoid ligands --- p.100
Chapter 9.6 --- Effect of PKC activation --- p.102
Chapter 9.7 --- Discussion --- p.104
Chapter 9.8 --- Conclusions --- p.106
Chapter Chapter 10 --- General Discussion and Conclusions --- p.107
Chapter 10.1 --- Development of DRG cell preparation --- p.107
Chapter 10.2 --- Effect of prostanoid mimetics on intracellular messengers --- p.108
Chapter 10.3 --- Regulation of prostacyclin receptors --- p.109
Chapter 10.4 --- Role of prostacyclin in pain modulation --- p.111
References --- p.113
49
"Characterization of toll-like receptor 4 in the neurons and glia of the dorsal root ganglion." 2014. http://library.cuhk.edu.hk/record=b6115727.
Full textAbstract:
背根神經節（DRG）上的初級感覺神經元通常負責感覺從環境中有害的刺激，但新出現的證據表明，它亦負責對危險的感覺。Toll-樣受體-4（TLR4）通常見於小膠質細胞，它是負責識別病原體相關分子模式（PAMPs）或損傷相關分子模式（DAMPs）並誘發炎症。奇怪的是，儘管TLR4在中樞神經系統通常見於神經膠質細胞，在DRG發現的TLR4僅見於初級感覺神經元，但從未見於周邊的衛星膠質細胞（SGC）。而重要的是，在感覺神經節中激活TLR4是會導致神經病理性疼痛的，但我們仍然未知道初級感覺神經元上的TLR4是否導致疼痛的唯一來源。本研究旨在探討在DRG細胞的TLR4信號傳導的分子和細胞機理，並探討在DRG的神經元和膠質細胞上TLR4活動的差異，在生物學上有甚麼意義。為了研究在DRG神經元和膠質細胞的相互作用，我們首先在一個既定的混合DRG細胞培養模型上研究了谷氨酰胺合成酶（ GS ）的表達模式。GS是一種只會在SGC上表達的特異性酶，並於神經元和神經膠質細胞之間的谷氨酰胺 - 谷氨酸循環產生相互作用。在典型的DRG細胞培養，神經元通過擴散因子促進了GS在神經膠質細胞上的表達，然而，GS的表達亦受到TLR4激動劑，即脂多醣（LPS），的抑制。這表明DRG神經元和神經膠質細胞的關係受到TLR4介導的炎症之影響。在混合DRG細胞中，我們對TLR4-免疫反應（IR）進行了鑑定，發現TLR4最主要的是表達在神經元細胞的表面。另外，LPS（ 1微克/毫升，2小時）會刺激混合DRG細胞，通過在DRG細胞中MyD88依賴性信令，誘導環加氧酶-2（COX -2），白細胞介素-1β（ IL-1β）和腫瘤壞死因子-α（TNFα）的轉錄。此外，在DRG細胞， LPS（ 1微克/毫升， 24小時）亦會觸發依賴COX-2 的前列腺素E2（PGE₂）和的前列環素（PGI₂）的產生。但在LPS刺激後，我們發現DRG神經元和神經膠質細胞都對 COX-2-IR呈陽性反應。這證明DRG神經膠質細胞對TLR4誘發的神經炎症也擔任一定的角色。
為了純粹研究神經膠質細胞有沒有任何TLR4活性，我們把神經元從混合DRG細胞中除去，從而把神經膠質細胞純化。出乎意料的是，在純化後，大約80的神經膠質細胞對TLR4 -IR呈陽性反應。而且，時間和濃度依賴性的研究表明，純化後的神經膠質細胞對LPS刺激的COX-2表達反應在有效性和效率上比混合DRG細胞的顯著更高。明顯地，神經元對神經膠質細胞的TLR4活性有抑制作用。我們並且發現，神經元的抑制作用是透過由細胞與細胞之間的接觸介導，而不是由擴散因子介導。
重要的是， LPS也能誘導純化後的神經膠質細胞去產生依賴COX-2活性的前列腺素E2（PGE₂）。反過來， PGE₂能區別地調節依賴TLR4的炎症基因轉錄，說明在DRG 由TLR4介導的神經炎症是受多重複雜的機理控制。然而有趣的是，從受熱休克性損害的感覺神經元所收集的培養基可以激活純化膠質細胞，並通過對TLR4局部依賴性的方式，誘導COX-2的轉錄。此外，我們利用斑馬魚作為疼痛行為反應的模型，發現COXs的活性與瞬時受體電位通道亞家族V1（ TRPV1）有密切關係。斑馬魚幼蟲的疼痛行為反應是一個適合於篩選新型鎮痛化合物的體內模型。
總括來說，透過細胞與細胞之間的接觸和擴散因子，感覺神經元可以控制神經膠質細胞的表型。我們的研究確定感覺神經元是在DRG中表達TLR4的主要細胞類型，但當神經元施加的抑制被削弱，SGC可以成為完全勝任TLR4信息傳遞的細胞。因此我們推測TLR4的活性在DRG中被嚴格調控，以防止不必要的神經炎症發生。至於未來，我們認為在DRG中的TLR4/COX-2/PGE₂信號通路可以成為研究方的新型鎮痛化合物的方向。而轉基因斑馬魚則可用作篩選新型鎮痛化合物的工具。
Primary sensory neurons of the dorsal root ganglia (DRG) are classically responsible for the detection of physiological stimuli from the environment, but emerging evidences suggests that they are also involved in the sensation of danger. Toll-like receptor 4 (TLR4) is commonly found on microglia for the recognition of pathogen- or damage- associated molecular patterns (PAMPs or DAMPs) and to the activation of TLR4 leads to inflammation. Curiously, while commonly found in glial cells in central nervous system, TLR4 expression was only found in primary sensory neurons but not the satellite glial cells (SGCs) in the DRG. Importantly, activation of TLR4 in sensory ganglia mediates neuropathic pain, but it remains unknown whether neurons are the only source of TLR4 activity. The present study aims to study the cellular and molecular mechanism(s) of TLR4 signalings and explore the biological significance of differential cellular TLR4 activity in the DRG.
To investigate neuron-glia interactions in the DRG, the expression of glutamine synthetase (GS), a SGC-specific enzyme in the glutamine-glutamate shuttle between neuron and glia, was studied in an established model of mixed DRG cells culture. In typical mixed DRG cell cultures, neurons promoted the GS expression in glial cells through diffusible factors. However, GS expression was negatively regulated by theTLR4 agonist, lipopolysaccharide (LPS), indicative of a change in neuron-glia relationships by TLR4 mediated inflammation. In mixed DRG cells, cell surface TLR4-immunoreactivity (-ir) was predominantly identified on the neurons. LPS (1 μg/mL, 2 h) stimulation induced cyclooxygenases-2 (COX-2), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNFα) transcription through MyD88-dependent signalings in DRG cells. Furthermore, LPS (1 μg/mL, 24 h) triggered COX-2-dependent production of prostaglandin E₂ (PGE₂) and prostacyclin (PGI₂) in mixed DRG cells.
To study the TLR4 activity of glial cells, glial cell cultures were purified by removing neurons from mixed DRG cell culture. Unexpectedly, approximately 80% of purified glial cells become TLR4-ir positive. Moreover, a time- and concentration-dependent study showed that the efficacy and efficiency of purified glial cells to express COX-2 in response to LPS was significantly higher than that of mixed DRG cells. We found that neuron inhibited glial cells through cell-cell contact, but not by diffusible factors. Importantly, LPS also induced COX-2 dependent PGE₂ production in purified glial cells. In turn, PGE₂ can differentially modulate TLR4-dependent gene transcription, suggestive of a complex regulation of TLR4-mediated inflammation in the DRG. Intriguingly, conditioned media from heat-shocked damaged sensory neurons activated purified glial cells to induce COX-2-transcription through a partially TLR4-dependent mechanism. Using zebrafish as a model of nocifensive behavior, we found that the activity of COXs was closely associated with the transient receptor potential channel subfamily V1 (TRPV1), and the nocifensive behavior of zebrafish larvae is suitable for in vivo screening of novel analgesic compounds.
To conclude, sensory neurons regulate the phenotypes of DRG glial cells through cell-cell contact and diffusible factors. Here, sensory neurons are confirmed to be the predominant cell type expressing TLR4 in the DRG, but SGCs become fully competent for TLR4 signalings when the neuronal inhibitions are diminished. We therefore hypothesize that TLR4 activity is tightly regulated in the DRG to prevent unwanted neuroinflammation. Future studies with genetically modified zebrafish can be used for the screening of novel analgesic compound targeting the TLR4/COX-2/PGE₂ signaling pathway.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Tse, Kai Hei.
Thesis (Ph.D.) Chinese University of Hong Kong, 2014.
Includes bibliographical references (leaves 190-222).
Abstracts also in Chinese.
50
"The characterization of G-protein coupled receptors in isolated rat dorsal root ganglion cells." 2011. http://library.cuhk.edu.hk/record=b5894627.
Full textAbstract:
Yeung, Barry Ho Sing.Thesis (M.Phil.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 137-154).
Abstracts in English and Chinese.
Abstract --- p.i
論文摘要 --- p.iv
Acknowledgements --- p.vii
Publications based on work in this thesis. --- p.ix
List of abbreviations --- p.x
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Dorsal root ganglion cells --- p.1
Chapter 1.1.1 --- Primary sensory neurons --- p.1
Chapter 1.1.2 --- Non-neuronal cells --- p.3
Chapter 1.1.2.1 --- Satellite glial cells --- p.3
Chapter 1.1.2.2 --- Schwann cells --- p.6
Chapter 1.2 --- Peripheral sensitization --- p.8
Chapter 1.3 --- Neuron-glia interactions --- p.9
Chapter 1.4 --- Aim of Thesis --- p.11
Chapter Chapter 2 --- "Materials, media, buffers and solutions" --- p.13
Chapter 2.1 --- Materials --- p.13
Chapter 2.2 --- "Culture media, buffer and solutions" --- p.19
Chapter 2.2.1 --- Culture media --- p.19
Chapter 2.2.2 --- General culture buffers and culture plate coating reagents --- p.19
Chapter 2.3 --- Antibodies used for identifying DRG cells --- p.23
Chapter 2.3.1 --- Primary antibodies --- p.23
Chapter 2.3.2 --- Secondary antibodies --- p.23
Chapter Chapter 3 --- Methods --- p.24
Chapter 3.1 --- Preparation of DRG cell cultures --- p.24
Chapter 3.2 --- Preparation of neuron-enriched and glial cell cultures --- p.25
Chapter 3.3 --- Immunocytochemistry --- p.26
Chapter 3.4 --- Immunohistochemistry --- p.27
Chapter 3.4 --- Determination of [3H]cAMP production in DRG cells --- p.28
Chapter 3.4.1 --- Principle of assay --- p.28
Chapter 3.4.2 --- Loading DRG cells with [3H]adenine --- p.28
Chapter 3.4.3 --- Column preparation --- p.28
Chapter 3.4.4 --- Measurement of [3H]cAMP production in DRG cells --- p.29
Chapter 3.4.5 --- Data analysis --- p.30
Chapter Chapter 4 --- Identification of DRG cells in dissociated cultures --- p.31
Chapter 4.1 --- Introduction --- p.31
Chapter 4.2 --- Aim of study --- p.34
Chapter 4.3 --- Results --- p.35
Chapter 4.3.1 --- Identification of DRG cells in isolated cultures --- p.35
Chapter 4.3.2 --- Activation and proliferation of glial cells in isolated cell cultures --- p.36
Chapter 4.3.3 --- Identification of glial cells in cultures --- p.38
Chapter 4.3.4 --- Modification of staining methods --- p.40
Chapter 4.3.5 --- Immunohistochemistry to identify DRG cells in DRG slices --- p.42
Chapter 4.3.6 --- Comparison of antibody staining in whole DRG and isolated DRG cells --- p.44
Chapter 4.4 --- Discussion --- p.44
Chapter 4.5 --- Summary --- p.53
Chapter Chapter 5 --- Characterization of GPCRs in isolated DRG cultures --- p.69
Chapter 5.1 --- Introduction --- p.69
Chapter 5.1.1 --- G-protein coupled receptors --- p.69
Chapter 5.1.2 --- Pharmacological characterization of prostanoid receptors on DRG cells --- p.73
Chapter 5.1.3 --- Gs- and Gi/o-coupled GPCRs in DRG cells --- p.75
Chapter 5.1.3.1 --- Gs-coupled GPCR: β-adrenoceptors --- p.76
Chapter 5.1.3.2 --- Gs-coupled GPCR: CGRP receptors --- p.79
Chapter 5.1.3.3 --- Gi/o-coupled GPCR: α2-adrenoceptors --- p.82
Chapter 5.1.3.4 --- Gi/o-coupled GPCR: Cannabinoid receptors --- p.85
Chapter 5.1.3.5 --- Gi/o-coupled GPCR: 5-HT1Areceptors --- p.88
Chapter 5.1.3.6 --- Gi/o-coupled GPCR: opioid and opioid-receptor-like 1 receptors --- p.90
Chapter 5.2 --- Aims of study --- p.93
Chapter 5.3 --- Results --- p.94
Chapter 5.3.1 --- Characterization of prostanoid receptors in isolated DRG cells --- p.94
Chapter 5.3.2 --- Characterization of CGRP receptors in isolated DRG cells --- p.96
Chapter 5.3.3 --- Investigation of the effect of CGRP8.37 on CGRP responses --- p.97
Chapter 5.3.4 --- Characterization of β1-adrenoceptors in isolated DRG cells --- p.97
Chapter 5.3.5 --- Characterization of β2-adrenoceptors in isolated DRG cells --- p.98
Chapter 5.3.6 --- Identification of β-adrenoceptor subtype mediating isoprenaline-stimulated responses.. --- p.99
Chapter 5.3.7 --- Characterization of α2-adrenceptors in isolated DRG cells --- p.100
Chapter 5.3.8 --- Characterization of cannabinoid 1 receptors in isolated DRG cells ... --- p.100
Chapter 5.3.9 --- Characterization of cannabinoid 2 receptors in isolated DRG cells --- p.101
Chapter 5.3.10 --- Characterization of 5-HT1A receptors in isolated DRG cells --- p.101
Chapter 5.3.11 --- Characterization of μ-opioid receptors in isolated DRG cells --- p.102
Chapter 5.3.12 --- Characterization of opioid-receptor-like 1 receptors in isolated DRG cells --- p.102
Chapter 5.3.13 --- Effect of nerve growth factor on DRG cells --- p.103
Chapter 5.4 --- Discussion --- p.106
Chapter 5.5 --- Summary --- p.114
Chapter Chapter 6 --- Conclusion and further studies --- p.134
References --- p.137