Academic literature on the topic 'Agonist deslorelin'

The aim of this study was to evaluate the effectiveness of deslorelin acetate in the regulation of reproductive activity in captive leopard geckos (Eublepharis macularius). Fourteen healthy adult females were separated into two groups. Under general anaesthesia, deslorelin acetate implants (4.7 mg) or placebo implants were administered into the coelom of ten female geckos and four female geckos, respectively. One healthy adult male Leopard gecko was added to each group of females (five females with GnRH implants and two females with placebo implants). The geckos were regularly monitored over two breeding seasons (visual examination, weight control). Nesting sites were checked daily. There were no postoperative complications or any other health problems during the study. Implant administration did not result in long-term suppression of reproductive function. No significant differences were found in the number of clutches between the female groups (deslorelin implants versus placebo implants) or in the number of clutches between the two breeding seasons. Deslorelin acetate implants did not interfere with ovarian activity in captive female leopard geckos. The use of GnRH agonist implants is not an appropriate method for control of reproductive function in female leopard geckos.

The search for an alternative approach of estrus control (induction or suppression) in dogs is an important issue and the use of slow GnRH agonist-releasing implants has been the subject of frequent research in recent years. Studies to date demonstrate that the short- and long-term effects of deslorelin implants applicated at different time points of the prepubertal period are similar to those of adult dogs; however, there are important differences. The age of the prepubertal bitch and the dosage appear to be the main determinants of the response to deslorelin, as well as the individual metabolism of the bitch. Recent studies reported that the deslorelin-mediated long-term delay of puberty does not have negative carry-over effects on subsequent ovarian functionality, serum steroid hormone concentrations, uterine health, and fertility; however, more molecular studies are needed to determine the effects of application time of GnRH agonists on hormone concentrations and peripheral receptor expression. Furthermore, the long-term effects of delay of puberty with deslorelin on joint health, tumor development, the immune system, and social behavior deserve further investigations.

The contraceptive and endocrine effects of long-term treatment with implants containing the GnRH agonist deslorelin were investigated in female tammar wallabies (Macropus eugenii). Fertility was successfully inhibited for 515 ± 87 days after treatment with a 5 mg deslorelin implant (n= 7), while control animals gave birth to their first young 159 ± 47 days after placebo implant administration (n= 8). The duration of contraception was highly variable, ranging from 344 to 761 days. The strict reproductive seasonality in the tammar wallaby was maintained once the implant had expired. This inhibition of reproduction was associated with a significant reduction in basal LH concentrations and a cessation of oestrous cycles, as evidenced by low progesterone concentrations. There was evidence to suggest that some aspect of either blastocyst survival, luteal reactivation, pregnancy or birth may be affected by deslorelin treatment in some animals. These results show that long-term inhibition of fertility in the female tammar wallaby is possible using slow-release deslorelin implants. The effects of deslorelin treatment were fully reversible and there was no evidence of negative side effects. Slow-release GnRH agonist implants may represent a practicable method for reproductive management of captive and semi-wild populations of marsupials.

In the present study, we tested the effect of treatment with a slow-release implant containing the gonadotrophin-releasing hormone agonist DeslorelinTM (Peptech Animal Health Australia, North Ryde, NSW, Australia) on pituitary and testicular function in mature male dogs. Four dogs were treated with Deslorelin (6-mg implant) and four were used as controls (blank implant). In control dogs, there were no significant changes over the 12 months of the study in plasma concentrations of luteinising hormone (LH) or testosterone, or in testicular volume, semen output or semen quality. In Deslorelin-treated dogs, plasma concentrations of LH and testosterone were undetectable after 21 and 27 days, testicular volume fell to 35% of pretreatment values after 14 weeks and no ejaculates could be obtained after 6 weeks. Concentrations returned to the detectable range for testosterone after 44 weeks and for LH after 51 weeks and both were within the normal range after 52 weeks. Semen characteristics had recovered completely by 60 weeks after implantation. At this time, the testes and prostate glands were similar histologically to those of control dogs. We conclude that a single slow-release implant containing 6 mg Deslorelin has potential as a long-term, reversible antifertility agent for male dogs.

Eastern grey kangaroos are widespread on the east coast of Australia and frequently reach high densities in reserves and parkland near urban areas. Management of these populations is highly contentious and non-lethal fertility-control technologies are sought as an alternative option to manage population size. This study evaluated the potential of slow-release gonadotrophin-releasing hormone agonist (deslorelin) implants to inhibit reproduction in female kangaroos. Deslorelin treatment effectively inhibited reproduction in adult females for periods of 559 ± 111 days (n = 6) and 651 ± 21 days (n = 5) after administration of one or two 10-mg implants respectively. Animals treated with the lower dosage tended to resume breeding earlier than those that received a total of 20 mg of deslorelin (minimum duration of 18 months). Deslorelin treatment had no effect on blastocyst reactivation in a single treated female and repeat treatment had no negative side-effects. This study has demonstrated that slow-release deslorelin implants can successfully inhibit reproduction for extended periods in the female eastern grey kangaroos. This approach may have potential application in reproductive management of problem kangaroo populations.

The present study investigated the effects of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist deslorelin on reproduction in the common brushtail possum (Trichosurus vulpecula). Captive female brushtail possums were assigned to control (placebo implant), low dose (4.7 mg deslorelin) or high dose (9.4 mg deslorelin) groups; males were assigned to control or high dose (9.4 mg deslorelin) groups. The acute effects of deslorelin treatment at the level of the pituitary gland were similar between the two sexes, where a transient rise in luteinising hormone concentration was induced over the first 24 h. In females, this was associated with the disruption of the normal oestrous cycle and mating within 2–10 days in some treated individuals, but no young were subsequently detected. By 3 weeks after treatment, treated females became anoestrus and remained infertile for at least one breeding season. The effects of treatment were reversible in a subset of females that had their implants removed, although the time taken to produce offspring was variable. Paradoxically, male brushtail possums remained fertile during chronic deslorelin exposure. Despite significant declines in basal follicle-stimulating hormone and testosterone concentrations, as well as an inability to respond to a GnRH challenge, treated males sired as many offspring as control males and there was no evidence of testicular regression. In conclusion, there is potential to control reproduction in female brushtail possums by using chronic GnRH agonist treatment.

Induction of ovarian activity and ovulation is a valuable tool for the genetic management of ex situ populations of wildlife. Deslorelin, a gonadotropin releasing hormone (GnRH)-agonist, has been used earlier to induce oestrus in the grey wolf (Canis lupus). The objective of the present study was to determine the efficacy of Deslorelin (2.1 mg, Ovuplant®, Peptech Animal Health, Australia) for manipulating ovarian activity of the maned wolf, a species speculated to be an induced ovulator. Eight female (4–12 years old) maned wolves were (i) paired with a male (n = 3) or (ii) housed alone (n = 5). Of the 8 females, 1 (1 in a pair and 1 singleton) were implanted with Deslorelin under the vulvar mucosa for 12 days. The remaining 6 received implants in the subcutaneous layer of the ear for 7 days. Fresh fecal samples were collected 5 to 7 days/week for 1 month before Deslorelin treatment through 6 weeks after implant withdrawal. Reproductive steroid metabolites were extracted from the fecal samples and quantified using a validated enzyme immunoassay. Baseline progestagen concentrations for each individual were calculated by an iterative process, whereby high values exceeding the mean plus one standard deviation were excluded. Comparisons of oestrogen and progestagen concentrations among pre-, peri-, and post-Deslorelin implant periods were performed using analysis of variance. Site and duration of the GnRH agonist treatment had no effect (P > 0.05) on subsequent ovarian responses. In paired females, oestrogen metabolites reached the highest (P < 0.05) concentration during Deslorelin (i.e. peri-) treatment (441.7 ± 20.2 ng g–1 of feces) compared to pre- (174.9 ± 16.7) and post- (177.8 ± 9.1) treatment. Progesterone metabolites rose (P < 0.05) above the baseline (indicative of ovulation) starting on Day 10 after the onset of Deslorelin implantation and remained elevated throughout the study (pre-, 11 645 ± 4798; peri-, 31 521 ± 6444; post-, 55 843 ± 2924 ng g–1 of feces). In singleton females, oestrogen metabolites increased (P < 0.05) immediately after implantation (from pre-, 184.2 ± 45.3 to peri-, 334.2 ± 29.8 ng g–1 of feces) and then declined (post-, 192.3 ± 12.4). Progestagen metabolites exhibited a similar pattern with a rise (P < 0.05) during Deslorelin treatment (from pre-, 3870 ± 1336 to peri-, 10 546 ± 880 ng g–1 of feces) followed by a decline after implant withdrawal (post-, 6171 ± 366), indicating that ovulation did not occur. These results suggest that Deslorelin can induce ovarian activity in the maned wolf. However, administration of an ovulatory agent after Deslorelin treatment may be required in females managed in the absence of a male, further supporting the assertion that this species is an induced ovulator. Funded by the Morris Animal Foundation.

In recent years fertility control has been proposed as an ethically acceptable alternative to lethal control techniques when managing overabundant kangaroo populations. A promising non-steroidal, non-immunological approach to contraception in female kangaroos involves the use of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist deslorelin. The practicality of using deslorelin implants as a management option is dependant on its effective inhibition of reproduction without negative physical or behavioural side-effects. This study investigated the behavioural effects of deslorelin implants in female eastern grey kangaroos. Treatment had no detectable effects on crepuscular activity. Alterations in the frequency of sexual interactions were observed in deslorelin-treated females, with a behavioural oestrus induced ~3 days after combined removal of pouch young and deslorelin administration. Copulation was observed during this early oestrous period, but conception was not achieved and pouch young were not observed in any treated females. Control females gave birth within 69.6 ± 10.4 days (mean ± s.e.m., n = 9) of placebo implant administration. The first births observed in treated animals were on Days 510, 637 and 643 after treatment. The remaining seven treated animals had not bred by the end of the study, a period of 647 days.

Effective and humane management strategies for coyotes (Canis latrans) remain elusive. We hypothesised that exposure to a high dose of a gonadotrophin-releasing hormone (GnRH) agonist would cause prolonged suppression of the reproductive axis. Two groups of male coyotes were administered 47 mg deslorelin in the form of either five 9.4-mg controlled-release Suprelorin (Peptech Animal Health, Macquarie Park NSW, Australia) implants (n = 3) or 10 4.7-mg implants (n = 5). In the first group, deslorelin suppressed plasma LH, testosterone and testes volume in two of three coyotes for three breeding seasons. In the second group, two of five deslorelin-treated coyotes had no sperm production after 1 year and plasma LH, FSH, testosterone and testes volume were suppressed. Although plasma gonadotropins and testosterone were suppressed in three treated coyotes in group two, testes volume and sperm production were evident. Because the duration of suppression differed among individual coyotes, we further hypothesised that a variation in deslorelin release underlay the variability. To test this, we analysed in vivo plasma profiles of deslorelin concentrations. These profiles suggested that deslorelin concentrations >100 pg mL–1 are required to maintain suppression in male coyotes. For field implementation, the development of an implant capable of releasing deslorelin for the life of the coyote is necessary.

The efficacy of one or multiple doses of an injectable formulation of deslorelin (a GnRH agonist) was evaluated to induce estrus in anestrous bitches. Thirteen animals composed three groups: group 1 (n=5, single IM injection of 2mg deslorelin), group 2 (n=5, four IM injections of 2mg deslorelin in alternate days), and control group (n=3, four IM saline injections in alternate days). Daily clinical evaluations, sexual behavior, vaginal cytology, plasma progesterone concentration, ovaryhysterectomy and macroscopic evaluation of the uterus and ovaries were done. In group 1, none of the bitches showed signs of estrus, while two developed clinical signs and vaginal cytology of proestrus. In group 2, all animals presented proestrus, four presented estrus, and three ovulated; resulting in a functional corpus luteum and high progesterone concentration until day 25 of diestrus, when ovaryhysterectomy was performed. The duration of the stages of deslorelin induced cycles and the progesterone profile were similar to those described in the literature, and no side effects were observed. In conclusion, injectable formulation of deslorelin in multiple injections was effective to induce fertile estrus in anestrous bitches.

The aim in the present study was to evaluate the impact of treatment with a slow release implant containing the GnRH agonist deslorelin on the pituitary gonadal axis and on sperm production in adult male dogs. The reason for the study was to explore the potential of these implants to achieve long term, reversible contraception in dogs. Three dose rates of deslorelin, 3mg, 6mg and 12mg were used in the implants in the study. The effect of the implants on pituitary and testicular function was monitored by measuring plasma LH and testosterone concentrations, testicular volume and semen characteristics. The degree of desensitization of the pituitary gonadotrophs and Leydig cells during treatment with deslorelin was measured by challenging the dogs with injections of GnRH and bovine LH at 0, 15, 25, 40, and 100 days after implantation, and measuring the plasma LH and testosterone responses to challenge. The effect of the deslorelin implants on the reproductive physiology of the dogs was characterized by a reduction in plasma LH and testosterone concentrations to undetectable levels within 3 weeks of implantation. Histological findings showed atrophic changes in seminiferous tubules, ductus epididymides and prostate gland after 25 days of treatment, the atrophy becoming progressively more severe on day 40 and 100 after implantation. Only spermatogonia and Sertoli cells were present in seminiferous tubules after 100 days.

Les implants contenant l'agoniste de la GnRH desloréline (Suprelorin®4,7mg, Virbac, Carros, France) ont un mode d'action en deux temps permettant l'activation et l'inhibition de la fonction de reproduction chez la chienne. Chacun de ces mécanismes a des applications cliniques, depuis l'induction des chaleurs jusqu'à la stérilisation chimique. D'un point de vue scientifique cependant les données chez la chiennes se limitent principalement à des animaux d'expérimentation (Trigg et al. 2001) : leur utilisation potentielle est ainsi très peu détaillée. 173 chiennes (dont 24 beagles d'expérimentation) ont ainsi été inclues dans 6 différentes protocoles pour documenter leur utilisation. Quand l'implant est utilisé pour l'induction des chaleurs, il était administré durant l'anœstrus et retiré juste après l'ovulation (déterminée quand la progestéronémie est de 6 ng/mL). Les 64 chiennes ayant participé à ces différents protocoles ont toutes présenté un œstrus induit. Pour 32 d'entre elles, celui est survenu 4,3±1,4 jours [2 à 7 jours après] suite à l'administration de l'implant. Des cycles anovulatoires ont été rapportés chez 14 de ces 64 chiennes, mais aucun facteur permettant de différencier ces chiennes de celles qui ovulent n'a pu être identifié. Quand l'implant était administré en anœstrus précoce, 2 chiennes sur 22 (9,1%) ont conduit une gestation a terme, alors que quand le traitement avait lieu en anœstrus tardif, cela a été le cas pour 16 chiennes sur 23 (69.6%). La taille moyenne de ces portées était de 6,7±3,5 chiots. Une insuffisance lutéale a été suspectée dans 5 cas: 2 de ces chiennes n'étaient pas gestantes au moment du diagnostic de gestation, une a mis bas prématurément 58 jours post-ovulation, le propriétaire refusant de supplémenter sa chienne. Les deux chiennes restantes ont été supplémentées avec de la progestérone par voie orale et mirent bas naturellement. Ces implants ont également été utilisés chez 109 chiennes en vue d'obtenir une stérilisation chimique. La réponse clinique au traitement était principalement dépendante du stade du cycle auquel celui-ci était administré. Les mêmes caractéristiques que celles vues lors de l'induction de l'œstrus ont été retrouvées lorsque l'implant était utilisé en anœstrus. Des chaleurs induites sont également survenues chez 3 chiennes sur 15 implantées en diœstrus. Quand cela était observé, l'implant était retiré, des niveaux élevés de progestérone et d'œstrogènes au même moment pouvant favoriser le développement de pyomètre. Chez une de ces chiennes, l'œstrus induit est survenu alors que la progestéronémie était supérieure à 60ng/mL, ce qui était bien supérieur au palier proposé par Trigg et al (2001), qui n'avaient pas observé de chaleurs induites quand la progestéronémie était supérieure à 5ng/mL. Chez 12 chiennes, l'œstrus induit a entrainé ainsi des effets secondaires qui ont conduit à l'arrêt du traitement : 3 chiennes en diœstrus, 7 chiennes ayant présenté des chaleurs persistantes qui ont duré plus de 30 jours et 2 chiennes qui ont présenté une lactation persistante. Par conséquent, les chiennes implantées devraient être contrôlées 30 jours après la pose de l'implant pour s'assurer que les chaleurs induites sont bien terminées et, si non, un examen échographique du tractus génital est recommandé pour vérifier la présence ou non de kystes ovariens
The mode of action of desloréline implants (Suprelorin®4,7mg, Virbac, Carros, France) allows activation and inhibition of the estrous cycle, with both clinical applications (from estrus induction to chemical sterilization). From a scientific background however, data concerning these different uses were mainly restricted to experimental bitches (Trigg et al. 2001) and yet no clear guidelines concerning the use of this product in females has been edicted. 173 bitches (including 24 experimental beagles) were includes in 6 different experiments to assess the use of these implants from the two perspectives. When used for estrus induction, the implant was administered during anœstrus and removed just after occurrence of ovulation (defined as progesterone level >5-6 ng/mL). All 64 bitches included in these experiments expressed an induced oestrus. For 32 of them, it occurred 4,3±1,4 days [2 to 7 days after] following implant administration. Anovulatory cycles were reported in 14 of these 64 bitches, but no statistical difference could be enlightened to discriminate the ones that ovulated and the ones that did not. When the implant was administered in early anoestrus, 2 out of 22 (9.1%) bitches carried their pregnancy to term while, when implanted in late anoestrus, this concerned 16 out of 23 (69.6%) bitches. Mean litter size obtained was 6.7±3.5 puppies. Luteal failure was suspected in 5 cases: 2 bitches were not pregnant at the time of pregnancy diagnosis and one gave birth 58 days post-ovulation as the owner refused supplementation. The two remaining bitches were supplemented with oral progresterone and gave birth normally. These implants were also used in 109 bitches in the purpose of chemical sterilization. The clinical response was depending of the stage of the cycle. The same features than for oestrus induction were obtained when administering the treatment in anoestrus. Oestrus induction also concerned 3 out of 15 bitches implanted in diestrus. When this was observed, implants were removed, as concomitant high levels of progesterone and estrogens may favored occurrence of uterine disorders. In one of these diestrous bitches, oestrus was induced with progesterone levels >60 ng/mL, which was different from the threshold proposed by Trigg et al (2001), who did not experience oestrus induction when bitches were above 5 ng/mL. In 15 bitches, the induced oestrus lead to side effects that required to stop the treatment: 3 bitches in diestrus, 7 bitches presenting persistent heats which lasts more than 30 days and 5 bitches presenting persistent lactation. Therefore, implanted bitches should be controlled after 30 days to ensure that heats are over and if not, ultrasound examination of the genital tract is advised to rule out the presence of ovarian cysts. Development of medical protocols to avoid the induced oestrus may change this. We tried different strategies to prevent the occurrence of this phenomenon. The use of the aromatase inhibitor anastrozole and the anti-estrogen clomifen did not give satisfying results (3/3 induced oestrus with anastrozole, 5/8 induced oestrus with clomifen). Better results were obtained with the progestagen osaterone acetate: 11 out of 16 bitches did not express induced oestrus, but the phenomenon was not completely prevented. The best results were obtained when implanting prepubertal bitches: none of the 24 animals exhibited oestrus after implant administration. Further data are still required to determine at which frequency the treatment should be administered in order to maintain its effect. However, with one implant administration, bitches, the contraceptive effect lasted less than 180 days in 5 bitches, between 180 and 365 days in 15 bitches and more than 365 days in 19 bitches

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Avaliar em vacas Nelore (Bos indicus) tratadas por longo prazo (70 dias) com implantes subcutâneos de agonista de GnRH (deslorelina- -Suprelorin® 4,7 mg) a dinâmica folicular ovariana e as concentrações plasmáticas do hormônio folículo estimulante (FSH), do hormônio luteinizante (LH) e da progesterona (P4) durante os últimos 20 dias do tratamento, e a dinâmica folicular ovariana e as concentrações de P4 da remoção do implante até a ovulação. Quinze vacas Nelore com escore de condição corporal (ECC) 3 tiveram sua ovulação sincronizada. No dia da detecção da ovulação, 10 animais foram selecionados para serem submetidos ao tratamento com implante subcutâneo de deslorelina. Nos últimos 20 dias do período de tratamento, foram realizados exames ultrassonográficos, a cada 2-3 dias, para caracterização da dinâmica folicular e registro dos folículos, que foram classificados de acordo com o diâmetro como: I (< 0,4 cm), II (0,4-0,6cm) e III (> 0,6cm). Neste mesmo período foram coletadas amostras de sangue para mensuração das concentrações plasmáticas de FSH, LH e P4. Os resultados foram submetidos à análise de variância e as diferenças entre as médias foram determinadas através do teste de Tukey. Durante os 70 dias de tratamento com a deslorelina nenhum animal ovulou, apesar de não ter sido observado a supressão do desenvolvimento folicular. Esse achado ultrassonográfico foi confirmado pelos resultados da concentração plasmática de P4, que se manteve em média abaixo de 0,16 ng/mL. Durante os últimos 20 dias de tratamento, quatro animais apresentaram desenvolvimento folicular com diâmetro máximo variando entre 0,4 a 0,6 cm, enquanto que nos três restantes foram observados diâmetros superiores a 0,9 a 1,2 cm. As secreções de FSH e LH não foram abolidas ao longo do estudo. Após a remoção...
The objective of the present study was to evaluate in Nelore cows (Bos indicus) treated for a long period (70 days) with subcutaneous implants of deslorelin (GnRH agonist-Suprelorin® 4,7mg) the ovarian follicular dynamics and plasma concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and progesterone (P4) during the last 20 days of treatment and the ovarian follicular dynamics and plasma concentrations of P4 from the removal of the implant until the ovulation. Fifteen Nelore cows with body condition score (BCS) 3 had their ovulation synchronized. At the day of the detection of ovulation 10 animals were randomly selected to receive subcutaneous implant of deslorelin. In the last 20 days of the period of implantation, ultrasonographic scans were realized, every 2-3 days, in order to characterize the follicular dynamics and to register the follicles which were classified according to diameter as: I (< 0,4 cm), II (0,4-0,6cm) and III (> 0,6cm). Simultaneously, blood samples were collected to measure plasma concentrations of FSH, LH and P4. Results were tested by analysis of variance and difference between means were defined using Tukey’s test. During the 70 days of deslorelin implantation none of the animals ovulated, despite of the implant not suppressing all follicular development. This ultrasonographic finding was confirmed by the results of P4 plasma concentrations, which was kept in average below 0,16 ng/mL. During the last 20 days of implantation, four animals presented follicular development with maximum diameter ranging through 0,4 to 0,6 cm while in the three remaining animals the observed diameter ranged through 0,9 to 1,2 cm. The secretion of LH and FSH was not entirely suppressed during the study. After the removal of the deslorelin subcutaneous implant (Suprelorin® 4,7 mg), the period of... (Complete abstract click electronic access below)

Orientador: João Carlos Pinheiro Ferreira
Banca: Eunice Oba
Banca: Lindsay Unno Gimenes
Banca: Sony Dimas Bicudo
Banca: Thales Ricardo Rigo Barreiros
Resumo: Avaliar em vacas Nelore (Bos indicus) tratadas por longo prazo (70 dias) com implantes subcutâneos de agonista de GnRH (deslorelina- -Suprelorin® 4,7 mg) a dinâmica folicular ovariana e as concentrações plasmáticas do hormônio folículo estimulante (FSH), do hormônio luteinizante (LH) e da progesterona (P4) durante os últimos 20 dias do tratamento, e a dinâmica folicular ovariana e as concentrações de P4 da remoção do implante até a ovulação. Quinze vacas Nelore com escore de condição corporal (ECC) 3 tiveram sua ovulação sincronizada. No dia da detecção da ovulação, 10 animais foram selecionados para serem submetidos ao tratamento com implante subcutâneo de deslorelina. Nos últimos 20 dias do período de tratamento, foram realizados exames ultrassonográficos, a cada 2-3 dias, para caracterização da dinâmica folicular e registro dos folículos, que foram classificados de acordo com o diâmetro como: I (< 0,4 cm), II (0,4-0,6cm) e III (> 0,6cm). Neste mesmo período foram coletadas amostras de sangue para mensuração das concentrações plasmáticas de FSH, LH e P4. Os resultados foram submetidos à análise de variância e as diferenças entre as médias foram determinadas através do teste de Tukey. Durante os 70 dias de tratamento com a deslorelina nenhum animal ovulou, apesar de não ter sido observado a supressão do desenvolvimento folicular. Esse achado ultrassonográfico foi confirmado pelos resultados da concentração plasmática de P4, que se manteve em média abaixo de 0,16 ng/mL. Durante os últimos 20 dias de tratamento, quatro animais apresentaram desenvolvimento folicular com diâmetro máximo variando entre 0,4 a 0,6 cm, enquanto que nos três restantes foram observados diâmetros superiores a 0,9 a 1,2 cm. As secreções de FSH e LH não foram abolidas ao longo do estudo. Após a remoção... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objective of the present study was to evaluate in Nelore cows (Bos indicus) treated for a long period (70 days) with subcutaneous implants of deslorelin (GnRH agonist-Suprelorin® 4,7mg) the ovarian follicular dynamics and plasma concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and progesterone (P4) during the last 20 days of treatment and the ovarian follicular dynamics and plasma concentrations of P4 from the removal of the implant until the ovulation. Fifteen Nelore cows with body condition score (BCS) 3 had their ovulation synchronized. At the day of the detection of ovulation 10 animals were randomly selected to receive subcutaneous implant of deslorelin. In the last 20 days of the period of implantation, ultrasonographic scans were realized, every 2-3 days, in order to characterize the follicular dynamics and to register the follicles which were classified according to diameter as: I (< 0,4 cm), II (0,4-0,6cm) and III (> 0,6cm). Simultaneously, blood samples were collected to measure plasma concentrations of FSH, LH and P4. Results were tested by analysis of variance and difference between means were defined using Tukey's test. During the 70 days of deslorelin implantation none of the animals ovulated, despite of the implant not suppressing all follicular development. This ultrasonographic finding was confirmed by the results of P4 plasma concentrations, which was kept in average below 0,16 ng/mL. During the last 20 days of implantation, four animals presented follicular development with maximum diameter ranging through 0,4 to 0,6 cm while in the three remaining animals the observed diameter ranged through 0,9 to 1,2 cm. The secretion of LH and FSH was not entirely suppressed during the study. After the removal of the deslorelin subcutaneous implant (Suprelorin® 4,7 mg), the period of... (Complete abstract click electronic access below)
Mestre

Thesis by publication -- 8 co-authored articles.
Thesis (PhD)--Macquarie University, Division of Environmental and Life Sciences, Department of Biological Sciences.
Includes bibliographical references.
Preface -- Management issues of urban common brushtail possums (Trichosurus vulpecula): a loved or hated neighbour -- Effects of deslorelin implants on reproduction in the common brushtail possum (Trichosurus vulpecula) -- Brushtail possums (Trichosurus vulpecula) in metropolotan Sydney: population biology and response to contraceptive implants -- Strategic survey for Toxoplasma gondii and Neospora caninum in the common brushtail possum (Trichosurus vulpecula) from urban Sydney, Australia -- Leptospirosis serology in the common brushtail possum (Trichosurus vulpecula) from urban Sydney, Australia -- Conclusions.
The common brushtail possum (Trichosurus vulpecula) is indeed a common inhabitant of many Australian citites, and one of the few marsupials that has adapted well to the urban environment. Their close proximity to people provides a great opportunity to experience native wildlife in the backyard, however, their utilization of house roofs, bold behaviour and appetite for garden plants often leads to conflict with householders. Population numbers are sufficiently high to require ongoing management to minimise negative impacts for humans and brushtail possums alike in a socially acceptable manner. The aim of this thesis was to identify current management issues and address the need for improved and novel management strategies. The potential of slow-release implants, containing the GnRH agonist deslorelin, as a contraceptive agent for brushtail possums was tested on a captive population. Males appeared resistant to treatment, but deslorelin was found to inhibit reproduction in female brushtail possums for at least one breeding season, making it a promising tool to control fertility in some wild populations. A further aim was to trial deslorelin implants on a wild urban population, to collect more information about the urban biology of this species and to point out issues which have previously not been addressed. Close proximity and interaction of urban brushtail possums with humans and their domestic animals can increase the risk of disease exposure and transmission and influence the health of wild populations. Serosurveys showed that animals were readily exposed to Leptospira spp. and Toxoplasma gondii. This thesis also provides the first data on brushtail possum dispersal in urban areas, knowledge which is highly relevant to the development of management strategies such as fertility control. The findings from this research broaden our knowledge about urban brushtail possums and should assist wildlife authorities in developing alternative or improved management procedures.
Mode of access: World Wide Web.
xxv, 287 p. ill., maps

Female cattle (heifers) treated with deslorelin, an agonist of gonadotrophin-releasing hormone(GnRH), typically show a biphasic gonadotrophin response to treatment. During the acute phase (0 to 24 h), plasma concentrations of luteinising hormone (LH) are elevated. The acute phase is followed by GnRH receptor downregulation in the anterior pituitary gland, and the pituitary becomes desensitised to natural sequence GnRH. Heifers treated chronically with deslorelin therefore do not have pulsatile secretion of LH. However, heifers treated chronically with deslorelin commencing early in the oestrous cycle (Day 3), typically had elevated plasma concentrations of progesterone during the luteal phase compared with contemporary untreated heifers. It is unlikely that increased plasma progesterone in heifers treated with deslorelin, commencing early in the oestrous cycle, is due to ovulation in response to the acute rise in plasma LH, and subsequent formation of an accessory corpus luteum. The increase in plasma progesterone in these treated heifers might be due, therefore, to changes in patterns of LH secretion, which are accompanied by changes in the size and/or function of the corpus luteum. Heifers treated with deslorelin commencing later in the oestrous cycle may be induced to ovulate and develop an accessory corpus luteum. The aim in Experiments 1 and 2 of this thesis was to characterise LH secretion, and determine changes in size and steroidogenic activity of the corpus luteum, in heifers treated chronically with deslorelin, commencing on Day 3 of the oestrous cycle. Steroidogenic activity was ascertained by measuring tissue contents of progesterone, steroidogenic acute regulatory (StAR) protein and the key steroidogenic enzymes, cytochrome P450scc (P450scc) and 3ß-hydroxysteroid dehydrogenase, ⁵-⁴isomerase (3ß-HSD). The recently described StAR protein facilitates the transport of cholesterol to the inner mitochondrial membrane of steroidogenic cells, where P450scc is localised. Transport of cholesterol to the inner mitochondrial membrane is considered the ratelimiting step in steroidogenesis in all steroidogenic tissues. A further aim in the thesis was to determine the relationship between stage of the oestrous cycle (i.e. stage of the ovarian follicular wave) and the ability of deslorelin to induce ovulation during the acilte LH response phase. In Experiment 1, stage of the oestrous cycle was synchronised in randomly cycling Brahman heifers, using a standard progest-agen treatment. On Day 3 of the ensuing oestrous cycle, heifers were assigned to: Control (n=9), no treatment; Deslorelin (n=9), implanted subcutaneously with GnRH agonist (deslorelin) bioimplants. Heifers treated with deslorelin received approximately 25 g deslorelin/kg live weight/24 h). Blood samples for LH and progesterone analyses were taken immediately before implanting (Day 0) and 6 hours later, and on Days 1,3, 5, 8, 9, 10. On Day 10 of treatment (Day 13 of the oestrous cycle), all heifers were ovariectomised and the corpus luteum dissected from the ovary and weighed. Immediately after ovariectomy, all heifers received an injection of natural sequence GnRH (50 g i.m.) and blood samples were taken at 0 and 30 min to determine pituitary LH release. Progesterone content of the corpus luteum was determined by radioimmunoassay. Contents of StAR protein, P450scc, and 3ß-HSD were determined using Western Blot analyses. Experiment 2 was similar in design to Experiment 1, except that heifers treated with deslorelin received approximately 50 g deslorelin/kg live weight/24 h. Also, in Experiment 2, heifers were bled on Days 1,3,5,7,9,10. The trends in the treatment responses were similar for Experiments 1 and 2 and pooled data are presented below. Treatment with deslorelin caused an acute increase in the plasma concentration of LH and, at 6h after implanting, treated heifers had greater (P<0.01) plasma LH (1.4 ±0.1 ng/ml) than control heifers (0.6 ± 0.1 ng/ml). Plasma LH in implanted heifers had declined by Day 1; however, mean LH from Day 1 to 10 of treatment was greater (P<0.01) for implanted heifers (0.8 ± 0.1 ng/ml) than control heifers (0.5 ± 0.1 ng/ml). On Day 10, control heifers had an increase (P<0.01) in plasma LH after injection of GnRH (LH 1.73 ± 0.23 ng/ml), but this did not occur in heifers implanted with deslorelin (LH 0.11 ±0.08 ng/ml). Plasma progesterone concentrations increased from Day 0 to Day 10 for both control heifers and heifers treated with deslorelin. On Day 10, plasma progesterone was greater (P<0.01) for heifers implanted with deslorelin (18.9 ± 3.5 ng/ml) than control heifers (9.1 ± 1.3 ng/ml). Corpus luteum weight was greater (P<0.05) for implanted (4.2 ±0.4 g) than control (3.1 ± 0.2 g) heifers. The amount of progesterone per corpus luteum was also greater (P0.01l) for treated heifers (164 ±20 g per corpus luteum) than control heifers (88 ± 13 g per corpus luteum). The amount of StAR protein per total corpus luteum was greater (P<0.05) for heifers treated with deslorelin (2.2 ±0.3 arbitrary units) than control heifers (1.2 ± 0.2 arbitrary units). The relative content of StAR protein per unit weight of corpus luteum was greater in treated heifers (1.8 ± 0.3 arbitrary units/g) compared with control heifers (1.5 ± 0.1 arbitrary units/g), but this difference was not significant. The relative content of P450scc per total corpus luteum was greater (P<0.01) in treated heifers (2.2 ± 0.2 arbitrary units) compared with control heifers (1.4 ± 0.2 arbitrary units). The relative content of P450scc per unit weight corpus luteum was also greater (P<0.05) in treated heifers (1.9 ±0.2 arbitrary units/g) compared with control heifers (1.2 ±0.1 arbitrary units/g). Relative content of 3ß-HSD per unit weight of corpus luteum tissue tended to be greater (Experiment 1: P=0.09; Experiment 2: P=0.72) in heifers treated with deslorelin (1.57 ± 0.15 arbitrary units/g) than in control heifers (1.49 ± 0.15 arbitrary units/g) but this was not significant. Relative content of 3ß-HSD per total corpus luteum likewise tended to be greater (P=0.20) in heifers treated with deslorelin (1.91 ± 0.25 arbitrary units) than in control heifers (1.51 ± 0.28 arbitrary units), but this also was not significant. In Experiment 3, stage of the oestrous cycle was synchronised in Brahman heifers, which were in random stages of the oestrous cycle, using a standard progestagen treatment. Heifers were then assigned to: Control (n=4), no treatment; or implanted with deslorelin (50 Lg/kg live weight/24 h) on different days of the oestrous cycle: D2 (n=4) implanted on Day 2; D4 (n=4) implanted on Day 4; D6 (n=4) implanted on Day 6; or D8 (n=4), implanted on Day 8 of the oestrous cycle. Ovarian follicle and corpus luteum status were monitored using ultrasonography for approximately 40 days. Heifers treated with deslorelin commencing on Day 2 of the oestrous cycle had follicles with a maximum diameter of 4.7 ± 0.3 mm at the time of treatment and did not ovulate or develop an accessory corpus luteum. The diameter of the largest follicle on Day 4 of the oestrous cycle was 6.5 ± 0.7 mm and two of four heifers ovulated and developed an accessory corpus luteum. The diameters of the two follicles that ovulated were 5.0 and 6.0 mm, while those that did not ovulate were 6.0 and 7.0 mm. On Day 6 of the oestrous cycle, each of the heifers had a 10 mm follicle that ovulated and developed an accessory corpus luteum. Heifers treated with deslorelin on Day 8 of the oestrous cycle had a relatively large follicle (8.63 ± 0.94 rum), but no heifers in this group ovulated. In 4 of 6 heifers that ovulated and developed an accessory corpus luteum, the spontaneous corpus luteum persisted for 11 to 19 days longer than the spontaneous corpus luteum in control heifers, even after the accessory corpus luteum had regressed. . The induced corpus luteum may have increased PGF₂receptors, or increased numbers of large luteal cells in the corpus luteum. Also, the presence of two corpora lutea might have produced sufficient oxytocin to cause downregulation of endometrial oxytocin receptors. The acute increase in plasma concentration of LH subsequent to implantation of heifers with deslorelin was consistent with previous findings. The rise in plasma LH was sufficient to induce ovulation of follicles of relatively small diameter (5 to 6 mm). This observation indicated that LH receptors sufficient for a response to a preovulatory LH surge are expressed in 6-7 mm follicles in Brahman (Bos indicus) heifers. Basal concentrations of plasma LH were consistently greater in heifers receiving deslorelin compared with untreated heifers. Increased basal LH in heifers treated with deslorelin was associated with greater concentrations of plasma progesterone. Because heifers treated with deslorelin would not have pulsatile secretion of LH, it could be concluded that basal secretion of LH is an important determinant of corpus luteum function and progesterone secretion in cattle. Heifers treated with deslorelin also had a larger corpus luteum and increased corpus luteum contents of StAR protein and P450scc. The latter findings are the first demonstration of concomitant increases in progesterone secretion, size of the corpus luteum and steroidogenic activity of luteal cells in a female mammal treated with GnRH agonist. Progesterone is required for the establishment and maintenance of pregnancy in cattle, and it is possible that treatment with a GnRH agonist may stimulate increased progesterone secretion sufficient to enhance conceptions to artificial insemination and embryo transfer in cattle.

Project aims to determine "mechanisms of anterior pituitary gland function and testicular steroidogenesis which result in the increased testosterone secretion observed in male bovine treated with the GnRh agonist deslorelin".

In dogs, the most frequent diseases of the prostate gland are benign prostate gland hyperplasia (BPH), acute and chronic prostatitis, squamous metaplasia, and prostate tumors. New diagnostic tools comprise diagnostic markers in the blood and urine, as well as advanced imaging methods. The therapy can be initialized with the 5α-reductase-inhibitor finasteride or an anti-androgenic compound, and prolonged with a long-acting gonadotropin-releasing-hormone (GnRH)-agonist such as deslorelin. In case of prostatitis, effective antibiotics must be applied for weeks. Antibiotics must be able to penetrate into the prostate tissue; fluoroquinolones, clindamycin, and erythromycin are good choices and are in addition effective against mycoplasms. The chronical prostatitis cannot be differentiated from a neoplasia by sonography; a biopsy, histological, and bacteriological examination are required. Tumors of the prostate gland are seldom and mostly occur in castrated but in intact dogs. For the final diagnosis, a biopsy must be taken. Partial and total resection of the prostate gland by use of laser technique is possible but coincedes with many side effects and the prognosis is still futile. Immunotherapy combined with NSAIDs, targeted noninvasive thermotherapy, BRAF gene inhibitors, or prostate artery chemoembolization are promising methods.