The aim of the present research was to investigate the expression profiles of GnRH-R and neuropeptide Y (NPY) genes in brain and pituitary of Orange-spotted Grouper, Epinephelus coioides and also to understand the regulatory mechanism by administering different sex steroids. GnRH-R (TMD2 to TMD6) was partially involved cloned in this study. Tissue distribution analysis revealed a significant expression of GnRH-R in pituitary compared to others tissues. The expression of GnRH-R in brain and pituitary of groupers at different ages showed a significant increased during the fourth year, probably indicating the time of maturation. However, there was no significant difference in the expression of GnRH-R during different seasons. Treatment of two and three year old groupers with different sex steroids revealed an increase in the expression of GnRH-R in pituitary by E2 in both the age groups tested, while T could induce the expression of GnRH-R only in three year old groupers. The result, thus, indicates that the sensitivity of grouper to sex steroid is dependent on the age and the kind of steroid adminstered. In different sections of brain, the GnRH-R expression was in general lower in the group treated with E2 or T compared to the control group. The expression of the gene was more or less the same in two year and three year old control groups. This result may have been caused by suppression of GnRH-R expression in forebrain and midbrain after sex steroid injection. Administration of T induced a significant increase in the expression of GnRH-R in forebrain and midbrain, while E2 treatment did not have a similar effect. In hindbrain, the expression profile GnRH-R was not affected by sex steroid treatment in both two year and three year old groupers. The results suggest that sex steroids can only regulate the expression of GnRH-R in the forebrain and midbrain, probably due to the wide distribution of steroid¡¦s receptor in these regions. LHRH and pimozide injections to two year old groupers showed an increase in the expression of GnRH-R in pituitary after LHRH treatment while there was no stimulatory effect on other sections of the brain. In contrast, treating the fish with pimozide alone or pimozide together with LHRH did not stimulate GnRH-R expression in brain. Thus, the study suggests that LHRH can significantly increase the expression of GnRH-R in pituitary while dopamine has no stimulatory effect. Studies on NPY showed that the gene was distributed in different sections of brain especially in the forebrain but it was also present in gills, liver, intestine ¡K etc. The presence of NPY in gills, though less compared to that in brain, suggests that NPY might play an important role in osmosis regulation. The expression of NPY decreased with increase in age which may be due to the effect of other regulatory factors. Treatment of two and three year old groupers with different sex steroids did not effect the expression of NPY significantly in brain, which is different from other published reports. This may be due to the difference in the zoning of brain regions. In the present study, forebrain and midbrain were sampled together for analyses. The expression of NPY in brain did not change by treating the fish with LHRH or pimozide.

The physiological mechanisms through which nutrition mediates its effects in controlling reproduction are not well characterized. Both neural and endocrine components have been implicated in the communication of nutritional status to the central nervous system. Leptin, a hormone synthesized and secreted mainly by adipocytes, is heavily involved in this communication network. The objectives of studies reported herein were 1) to determine the effects of short-term restriction of nutrients on circulating leptin, leptin gene expression in adipose tissue, and leptin receptor (LR) gene expression in the adenohypophysis of ovariectomized cows; and 2) to investigate the responsiveness of the hypothalamic-adenohypophyseal (AP) axis of fasted and non-fasted cattle to leptin. Studies demonstrated that circulating concentrations of leptin and leptin gene expression in subcutaneous adipose tissue are decreased by fasting. Although 2 to 3 days of fasting did not affect patterns of release of luteinizing hormone (LH), cerebroventricular infusions of leptin increased mean circulating concentrations of LH in fasted, but not normal-fed cows, without affecting frequency or amplitude of pulses of LH. In vitro studies were conducted to determine whether the in vivo effects of leptin could be accounted for at the hypothalamic and/or AP levels. Leptin did not affect the release of gonadotropin-releasing hormone (GnRH) from hypothalamic-infundibular explants from either normal-fed or fasted cattle. Moreover, leptin did not affect the basal release of LH from bovine AP cells or AP explants from normal-fed cows. However, leptin induced a higher basal release of LH from AP explants of fasted cows and increased GnRH-stimulated release of LH from AP explants of normal-fed cows. Results demonstrate that leptin acts directly at the AP level to modulate the secretion of LH, and its effects are dependent upon nutritional status. Cellular mechanisms associated with the increased responsiveness of gonadotropes to leptin in fasted cows were investigated. Expression of LR and suppressor of cytokine signaling-3 (SOCS-3) in the adenohypophysis did not account for the increased responsiveness of fasted cows to leptin. Therefore, although leptin clearly stimulates the hypothalamic-gonadotropic axis in nutrient-restricted cattle, it is unclear why cattle maintained under neutral or positive energy balance are resistant to leptin.

Objectives were to determine if low-dose, continuous infusion of GnRH from Fall to Spring, would prevent seasonal anovulation in mares. Twenty Quarter Horse mares, ages 18 mo to 24 yrs, were stratified by age and body condition score and assigned randomly to either a saline control (n = 9) or GnRH (n = 11) treatment group. Treatments were instituted between September 23 and October 9, 2002. Gonadotropinreleasing hormone was delivered in 0.9% physiological saline via Alzet osmotic minipumps (Model 2004) placed sc at the base of the neck, with Silastic sham pumps placed in control mares. Pumps were inserted on day 3 following ovulation or during the follicular phase if ovulation had not occurred. Delivery rate of GnRH was 2.5 ug/h (60 ug/d) for the first 60 d, followed by 5.0 ug/h (120 ug/d) thereafter, with all pumps replaced every 30 d. By December 1, all mares had become anovulatory and remained anovulatory until February. Mean serum concentrations of LH were not affected by treatment in anovulatory mares. In contrast, control mares that exhibited ovulatory cycles after treatment onset had higher (P < 0.05) mean concentrations of LH during all phases of the estrous cycle except diestrus. Mean serum concentrations of FSH were not affected by treatment, but were lower (P < 0.05) from November though January relative to all other months in anovulatory mares. Interovulatory intervals in mares that cycled temporarily did not differ between groups. Ovulatory control mares had slightly larger (P < 0.10) follicles overall than GnRH-treated mares; however, ovulatory follicle diameters for control and GnRH-treated mares did not differ. Ovulatory control mares had higher (P < 0.10) mean concentrations of progesterone during metestrus and late diestrus. In a subgroup of control (n =5) and GnRH-treated (n = 5) mares, total releasable pools of LH in response to 1 mg GnRH did not differ between groups. Ovulation resumed in 3 control and 3 GnRH-treated mares by March 30. Results indicate that continuous infusion of native GnRH at the doses employed herein is not sufficient to maintain ovulatory cycles during the anovulatory season.

Le kisspeptine (kp) est un peptide, dérivé du gène kiss-1, jouant un rôle majeur dans le contrôle central de la fonction de reproduction en régulant la sécrétion du GnRH chez l’adulte mais également au cours du développement. Les neurones exprimant kiss-1 sont situés dans la région rostrale périventriculaire du 3ème ventricule (RP3V) et le noyau arqué (ARC). L’expression de kiss-1 est hautement régulée par les stéroides sexuels, positivement dans RP3V et négativement dans ARC. Ces deux populations de neurones à kp semblent avoir des rôles différents. Les neurones à kp du RP3V seraient impliqués dans la genèse du pic préovulatoire et ceux de l’ARC dans la régulation de la sécrétion pulsatile de GnRH.L’objectif de la thèse était de déterminer la période de neurogenèse des neurones à kp ainsi que les variations de l’expression de kiss-1 et de kp dans ces deux régions au cours des différentes phases du développement chez le rat mâle et femelle.Nos résultats ont permis de cibler les périodes clés de l’ontogenèse des neurones à kp en montrant 1) que les neurones à kp de l’ARC naissent sur une période étendue à partir du jour embryonnaire (E)12,5; 2) l’existence d’une sous- expression péri-natale du kp dans l’ARC indépendante du sexe; 3) la mise en place, en période néonatale, de différences sexuelles dans les niveaux d’expression et la distribution neuroanatomique du kp; 4) l’existence de régulations péri-pubertaires de kp, dépendantes du sexe et de la région ; 5) la présence de fibres à kp dans des régions hypothalamiques suggère un rôle de kp au-delà de la fonction de reproduction. / Kisspeptin (kp) is a neuropeptide, derived from the kiss-1 gene, which plays a key role in the central control of reproduction by regulating GnRH secretion in adult but also during development. Cells which express kiss-1 are localized in two distincts hypothalamic regions: the rostral peri-ventricular third ventricule area (RP3V) and the arcuate nucleus (ARC). Kiss-1 expression is highly regulated by sex steroids: positively in the RP3V and negatively in the ARC. RP3V kp neurons have been implicated in the pre-ovulatory GnRH surge whereas ARC kp neurons may predominantly act on GnRH secretion pulsatility. The aim of this PhD work was to determine the neurogenesis period of kp neurons and changes of kiss-1 and kp expression in both regions during different stages of development in rats. Our results highlight key periods of kp neurons ontogenesis and show that: 1) ARC kp neurons are born during an extended embryonic neurogenesis period starting at embryonic day (E) 12,5; 2) a sex independent down-regulation of kp occurs during peri-natal period; 3) sex difference in the expression level and neuroanatomique distribution of kp establishes during neo-natal period; 4) kp was regulated during peri-pubertal period in sex and region dependant manner; 5) kp-ir fibers are detected throughout the septo-hypothalamic continuum suggesting that kp could be implicated in other functions than reproductive function.

Made available in DSpace on 2018-08-01T22:56:58Z (GMT). No. of bitstreams: 1 tese_9069_Thadeu de Castro20170509-83556.pdf: 2338723 bytes, checksum: 4d45ce105a21f94e9386fefcf563a79e (MD5) Previous issue date: 2017-02-15 / Em éguas o nível de progesterona plasmática (P4) diminui gradativamente iniciando no dia 6 do ciclo estral (dia 0 = dia da ovulação) e é associado com a baixa concentração do hormônio luteinizante (LH). Tem sido relatado que o resgate do CL durante luteólise está associado com o aumento de P4, LH e do fluxo sanguíneo do CL. A administração do hormônio liberador de gonadotrofina (GnRH) (20 µg/h) no dia 9 ou 10 do ciclo estral até a ovulação, aumentou os níveis de P4 (estimulo luteotrófico) logo após o tratamento. Além disso, o tratamento com LH em ratos aumentou o fluxo sanguíneo do ovário (efeito vasoativo). Assim, acredita-se que o LH liberado devido ao estimulo da aplicação exógena de GnRH poderá estimular as atividades do CL, aumentando os níveis sanguíneos de P4, o fluxo sanguíneo do CL e avascularidade do ovário hipselateral ao CL. Pretende-se avaliar com o presente estudo o efeito do tratamento de diferentes concentrações de GnRH sobre as concentrações de LH e P4, no fluxo sanguíneo do corpo lúteo e da arteria ovariana em éguas no dia 10 do ciclo estral. As éguas serão distribuídas de forma aleatória e divididas em três grupos deacordo com a dose de GnRH (Fertagyl; Intervet, Inc., Roseland, NJ, USA): G1 = 0 µg GnRH (n=9); G2 = 100 µg GnRH (n=8); e G3 = 300 µg GnRH (n=9). A administração do GnRH será por via intravenosa no dia 10 do ciclo estral. Exame ultrasonográfico e coleta das amostras de sangue serão feitos nos momentos: 0 (imediatamente antes do tratamento), 15 minutos, 30 minutos, 1 hora, 2 horas, 3 horas, 4 horas e 6 horas após o tratamento. Nas amostras de sangue será mensurada a concentração de LH e P4. Um aparelho de ultrassonogradia modo-B (escala cinza) equipado com a função color-Doppler (Aloka SSD-2000; Aloka America, Wallingford, CT, USA) com transdutor linear de 7.5-MHz será utilizado para obter as imagens. O modo spectral Doppler será utilizado para assessar a resistência sanguínea da arteria ovariana ipsilateral ao CL, baseado na resistance index (RI) do vaso sanguíneo. O fluxo sanguíneo do CL será estimado através de um programa de computador. Espera-se com este estudo determinar se diferentes doses de GnRH afeta a liberação de LH e P4, e sua interação com a vascularidade da arteria ovariana e do CL.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-12-19T18:38:39Z No. of bitstreams: 2 Tese - Jalsi Tacon Arruda - 2013.pdf: 4216712 bytes, checksum: ec49a9884c1f4b73b53a9b224c7c4aa1 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-12-22T11:01:46Z (GMT) No. of bitstreams: 2 Tese - Jalsi Tacon Arruda - 2013.pdf: 4216712 bytes, checksum: ec49a9884c1f4b73b53a9b224c7c4aa1 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-12-22T11:01:46Z (GMT). No. of bitstreams: 2 Tese - Jalsi Tacon Arruda - 2013.pdf: 4216712 bytes, checksum: ec49a9884c1f4b73b53a9b224c7c4aa1 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-07-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Infertility affects more couples and assisted reproduction techniques offer a possibility of treatment and the chance of having a child. Thus, the first attempt to ovulation induction is critical to the success of the cycle or even for future attempts is successful. Objective: To compare the protocols using GnRH agonist or antagonist for ovarian stimulation in normo-responders undergoing the first cycle of IVF/ICSI. Methods: we conducted a literature review on the history of ovulation induction controlled by medications. From the data available in the database of electronic medical records SISFERT used in the Laboratory of Human Reproduction (LabRep-HC-FM-UFG) a comparative retrospective observational study was conducted with 50 patients divided into two groups according to protocol: GnRH-agonist (leuprolide acetate 1 mg/day short protocol) or GnRHantagonist (Cetrorelix 0.25 mg/day), which received 150 IU/day of rFSH (follitropin alpha) and 250 µg of rhCG (alpha-coriogonadotrofina) in both groups. Results: Statistically significant differences were observed in the days of stimulation with rFSH, total dose of gonadotropin, days of use of GnRH, GnRH dose and total number of follicles (≥ 16 mm) on the day of the group rhCG GnRH agonist. There was no significant difference in other parameters, however, the number of oocytes retrieved was slightly higher in the GnRH agonist, but fertilization rate was higher in the GnRH-antagonist. Pregnancy rates and clinical chemistry were similar in both groups. Conclusions: although no significant differences in the results analyzed, the use of flexible antagonist protocol facilitates the handling and enables the patient using much lower doses of gonadotropins itself as the antagonist, reducing the cost of treatment when compared to the protocol with GnRH agonist. / A infertilidade afeta cada vez mais casais e as técnicas de reprodução assistida oferecem uma possibilidade de tratamento e a chance de ter um filho. Assim, a primeira tentativa de indução da ovulação é fundamental para o sucesso do ciclo ou, até mesmo, para que tentativas futuras sejam bem sucedidas. Objetivo: comparar os protocolos utilizando agonista ou antagonista do GnRH para estimulação ovariana em pacientes normo-respondedoras submetidas ao primeiro ciclo de FIV/ICSI. Métodos: foi realizada uma revisão da literatura sobre a história da indução da ovulação controlada por medicamentos. A partir dos dados disponíveis no banco de prontuários eletrônicos SISFERT utilizado pelo Laboratório de Reprodução Humana (LabRep–HC–FM–UFG), um estudo observacional retrospectivo comparativo foi conduzido com 50 pacientes distribuídas em dois grupos de acordo com o protocolo: GnRH-agonista (acetato de leuprolide 1 mg/dia protocolo curto) ou GnRH-antagonista (cetrorelix 0,25 mg/dia); e que receberam 150 UI/dia de rFSH (alfa-folitropina) e 250 µg de rhCG (alfa-coriogonadotrofina) em ambos os grupos. Resultados: foram observadas diferenças estatisticamente significativas nos dias de estimulação com rFSH, dose total de gonadotrofina, dias de uso do GnRH, dose total de GnRH e o número de folículos (≥ 16 mm) no dia do rhCG no grupo GnRH-agonista. Não houve diferença significativa nos outros parâmetros, no entanto, o número de oócitos recuperados foi ligeiramente maior no grupo GnRH-agonista, mas a taxa de fertilização foi maior no grupo GnRH-antagonista. As taxas de gravidez química e clínica foram similares nos dois grupos. Conclusões: embora não tenha havido diferenças significativas nos resultados analisados, o uso do protocolo flexível com antagonista facilita a manipulação pela paciente usuária e possibilita doses menores tanto de gonadotrofinas quanto do próprio antagonista, reduzindo o custo do tratamento quando comparado ao protocolo com agonista do GnRH

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-07-13T19:10:04Z No. of bitstreams: 1 texto completo.pdf: 252293 bytes, checksum: 1c80e8f3e74d50c3ed9b81b7885cf440 (MD5) / Made available in DSpace on 2017-07-13T19:10:04Z (GMT). No. of bitstreams: 1 texto completo.pdf: 252293 bytes, checksum: 1c80e8f3e74d50c3ed9b81b7885cf440 (MD5) Previous issue date: 2004-02-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O experimento foi conduzido no Setor de Caprinocultura do Departamento de Zootecnia da Universidade Federal de Viçosa, com o objetivo de avaliar o efeito da administração de hormônio liberador de gonadotrofina (GnRH) e hormônio luteinizante (LH) sobre a indução e sincronização da ovulação em cabras em anestro sazonal com estro induzido pelo acetato de medroxiprogesterona (MAP). Foram utilizadas 45 cabras lactantes (30 da raça Alpina e 15 da raça Saanen), com idade variando entre 2 e 6 anos, peso corporal médio de 55,25 ± 12,96 kg, escore de condição corporal de 2,91 ± 1,05 e produção leiteira de 1,11 ± 0,63 kg. Os animais foram sincronizados pela inserção de esponjas intravaginais contendo 60 mg de MAP por nove dias, administração de 200 UI de gonadotrofina coriônica eqüina (eCG) e 37,5 μg de PGF 2α no 7o dia, por via intramuscular (IM). Após a sincronização, os animais foram aleatoriamente divididos em três tratamentos com 15 animais cada. Os animais do T1 (controle) receberam 1 mL de solução salina, os do T2 receberam 5 mg do LH e os do T3, 12,5 μg do GnRH, por via IM nas 24 horas após a retirada xdas esponjas. A inseminação artificial (IA) foi realizada às 24 e 36 horas, após a retirada das esponjas, com sêmen fresco e diluído. A ovulação foi monitorada por exames ultra-sonográficos, via transretal, em intervalo de quatro horas até a detecção da ovulação, tendo início 12 horas após a retirada das esponjas. A gestação foi confirmada por exame ultra- sonográfico, via transretal, 25, 40 e 60 dias após a inseminação. Os parâmetros avaliados não diferiram entre os animais das duas raças. A percentagem de animais em estro encontrada neste experimento foi de 100,0; 73,3 e de 66,6%, e o intervalo da retirada da esponja ao início do estro foi em média de 34,8 ± 10,4; 29,3 ± 3,2 e de 31,5 ± 3,0 horas para os animais do tratamento-controle, LH e GnRH, respectivamente, não diferindo entre os tratamentos. A duração do estro também, não diferiu entre os três tratamentos. O intervalo médio da retirada da esponja à ovulação foi de 46,6 ± 9,3; 52,1 ± 5,1 e de 41,6 ± 8,7 horas para o tratamento-controle, LH e GnRH, respectivamente, com diferença entre os animais do tratamento LH e GnRH (P<0,01). A ovulação após as injeções ocorreu em média 21,3 ± 8,6; 26,8 ± 4,1 e 22,3 ± 13,3 horas, para o tratamento-controle, LH e GnRH, respectivamente, não havendo diferença entre os tratamentos. Houve diferença do intervalo do início do estro à ovulação para os animais do tratamento LH e GnRH em relação aos do controle (P<0,05). As taxas de gestação não diferiram entre os animais de todos os tratamentos, apesar de ser observada uma alta taxa de perda embrionária entre 25 e 40 dias de gestação nos animais do tratamento LH e GnRH. / The experiment was conducted in the section of Dairy Goat of Department of Animal Science of Federal University of Viçosa, with the objective to evaluate the effect of the administration of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) on the induction and synchronization of ovulation in does out of the breeding season with estrus induced by medroxyprogesterone acetate (MPA). Forty five does were used (Alpine, n = 30 and Saanen, n = 15) with aged between 2 and 6 years, an average body weight of 55. 25 ± 12.96 kg, body condition score of 2.91 ± 11.05 and milk yield of 1.11 ± 0.63 kg. The animals were synchronized by insertion intravaginal sponges impregnated with 60 mg of MPA) for nine days, associated with 200 IU of equine chorionic gonadotropin (eCG) and 37.5 μg of cloprostenol in the 7th day. After the synchronization, the animals were randomly allotted in three treatments with 15 animals each. The animals of treatment 1 (control) received 1 mL of saline solution, treatment 2 received 5 mg of LH and T3 received 12.5 μg of GnRH, by intramuscular injection, 24 hours after the removal of the intravaginal xiisponges. Artificial insemination was done at 24 and 36 hours after the sponge removal, with fresh and diluted semen. The ovulation was monitored by transrectal ultrasound at 4 hours interval until the detection of ovulation, beginning 12 hours after the sponge removal. Gestation was confirmed with the aid of transrectal ultrasound on the 25, 40 and 60 days after the AI. The evaluated parameters did not differ between the two breeds of animals. The percentage of animals in estrus observed in this experiment was of 100.0, 73.3 and 66.6% and the interval from sponge removal to estrus was of 34.8 ± 10.4; 29.3 ± 3.2 and of 31.5 ± 3.0 hours for the control, LH and GnRH treatments, respectively, not observing difference among the treatments. There was no difference for the estrus length among animals of the three treatments. The average interval from sponge removal to ovulation was of 46.6 ± 9.3, 52.1 ± 5.1 and of 41.6 ± 8.7 hours for the control, LH and GnRH treatments, respectively. There was difference (P<0,01) between LH and GnRH treatments. Ovulation after injections occurred on average 21.3 ± 8.6, 26.8 ± 4.1 and 22.3 ± 13.3 hours, for the control, LH and GnRH treatments respectively, not observing difference among the treatments. There was difference (P<0.05) from the beginning of estrus to ovulation for LH and GnRH treatments in relation to control. Gestation rates did not differ among the treatments, despite the high rate of embryonic loss observed between 25 and 40 days of gestation in the animals of LH and GnRH treatments.

Orientador: Renata Guimarães Moreira Whitton / Resumo: O eixo hipotálamo-hipófise-gônadas (HHG) modula o processo reprodutivo nos vertebrados e pode ser alvo de diversas substâncias que podem de alguma forma alterar a reprodução em diferentes espécies, dentre elas os teleósteos. Em condições favoráveis, ocorre a sinalização do hormônio liberador de gonadotropinas (GnRH), produzido e liberado por neurônios hipotalâmicos, que atua nas células gonadotrópicas da adeno-hipófise, estimulando a síntese e liberação do hormônio folículo-estimulante (Fsh) e o hormônio luteinizante (Lh). Esses, por sua vez, chegam às gônadas, promovendo a produção dos esteroides gonadais, maturação e liberação dos gametas. Enquanto o GnRH exerce papeis estimuladores, as ações do GnIH (hormônio inibidor de gonadotropinas) permanecem controversas para muitas espécies de teleósteos. Sabe-se que alguns compostos químicos podem interferir no funcionamento do eixo HHG dos peixes e os anti-inflamatórios não esteroidais (AINEs) podem atuar como desreguladores endócrinos e afetar a produção das gonadotropinas. O objetivo deste estudo foi avaliar os efeitos in vitro do GnRH e do GnIH, além dos AINEs – diclofenaco e ibuprofeno, na regulação da expressão gênica das gonadotropinas utilizando explantes de hipófise, e o efeitos dos AINEs sob a liberação dos esteroides gonadais em explantes de testículos, de uma espécie neotropical, Astyanax altiparanae. Nossos resultados mostraram que o cGnRH2 (chicken GnRH2) aumentou os níveis de expressão de fshb e lhb, e o zGnIH-3 (zeb... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The hypothalamus-pituitary-gonads (HPG) axis modulates the reproductive process in vertebrates and may be the target of several substances that may in some way alter reproduction in different species, including teleosts. Under favorable conditions, the gonadotropin releasing hormone (GnRH), produced and released by hypothalamic neurons acts in the adenohypophysis gonadotropic cells stimulates the synthesis and release of the follicle-stimulating hormone (Fsh) and the luteinizing hormone (LH), that act in the gonads promoting the production of gonadal steroids, for maturation and release of gametes. While GnRH exerts stimulatory roles, GnIH (gonadotropin inhinitory hormone) actions remain controversial for many species of teleosts. Some chemical compounds may interfere in the HPG axis in fish, and nonsteroidal anti-inflammatory drugs (NSAIDs) may act as endocrine disrupters and affect the production of gonadotropins. The objective of this study was to evaluate the in vitro effects of GnRH and GnIH and NSAIDs - diclofenac and ibuprofen - on the regulation of gonadotropins gene expression using pituitary explants and the effects of NSAIDs on the release of gonadal steroids in testicular explants from a Neotropical species, Astyanax altiparanae. Our results showed that in males, cGnRH2 (chicken GnRH2) increased the expression levels of fshb and lhb, and zGnIH-3 (zebrafish GnIH-3) had no direct effect on gonadotropin expression. However, zGnIH-3 stimulated the decrease of the expr... (Complete abstract click electronic access below) / Doutor

Prostaglandin F2a (PGF2a), oxytocin and gonadotropin releasing hormone (GnRH) have been used in bulls, rams, boars, stallions or rodents to increase sperm numbers in the ejaculate. Improving sperm quantity in the canine ejaculate would benefit all assisted reproductive techniques used in this species. The purpose of the present study was to evaluate the effects of PGF2a, oxytocin and GnRH on canine ejaculate characteristics. Eight, mature, medium size (25-30 kg), mixed breed dogs were randomly assigned to one of four treatment groups (N=2 dogs each); each group received one treatment per week for four weeks. Treatments were assigned based on a Latin Square design. A two-week training period was used to acclimate the dogs to manual semen collection. Treatments were 0.1 mg/kg PGF2a 15 minutes prior to collection, 2.5 units/dog oxytocin 10 minutes prior to collection, 50 mg/dog GnRH 60 minutes prior to collection, or 1.0 ml of saline 30 minutes prior to collection. An evaluator that was blinded to treatment analyzed ejaculate characteristics. Samples were evaluated for semen volume, concentration of spermatozoa per milliliter, motility, morphology, total sperm number and total morphologically normal motile sperm number (TNMS). In addition, a subjective ease of collection score was assigned following each collection (Scale 1-9, 1 being easiest to manually ejaculate). Semen concentration, motility and morphology were not different between treatments. Semen volume was greater for dogs treated with PGF2a or oxytocin compared to saline. Total sperm number and TNMS were greater when dogs were treated with PGF2a compared to oxytocin, GnRH and saline (p<0.05). The subjective ease of collection score was lower for dogs receiving PGF2a compared to GnRH or saline (p<0.05). In summary, administration of PGF2a or oxytocin prior to semen collection increased semen volume and PGF2a increased total sperm number in the ejaculate of the dog. It did not appear that treatment with GnRH had an effect on semen parameters evaluated in this study. / Master of Science

Two experiments were conducted to determine efficacy of GnRH analogs, Cystorelin (CYS, gonadorelin diacetate tytrahydrate) and Factrel (FAC, gonadorelin hydrochloride), for use in beef timed AI synchronization. In Experiment one 342 beef cows from 7 herds were assigned CYS or FAC treatment as part of the Ovsynch protocol (GnRH d 0 and 9, Lutalyse d 7). Cattle treated with FAC had greater tendency (P=.09) to be pregnant at d 45. One individual herd demonstrated FAC-treated cows had more pregnancies at day 45. In Experiment two, 18 beef cows received either CYS or FAC as part of the Ovsynch protocol, intensive blood samples, from time -30 to 525 min post GnRH, were collected at each GnRH injection. Ultrasounds were conducted daily over the course of the protocol. A treatment by phase interaction (P=.03) was found for the time to maximum LH concentration, where CYS-treated follicular cows had a shorter interval than did FAC treated follicular or luteal cows. The duration of detectable LH response showed a treatment by phase interaction (P = .02) where follicular and luteal CYS-treated cows had shorter interval than follicular or luteal FAC-treated cows. The variables maximum LH concentration, and area under LH curve did not differ. Cows treated with CYS had more (P=.02) non-dominant follicles. In Experiment three, 16 ewes randomly received either CYS, FAT or Fertagyl (FER; gonadorelin diacetaate tytrahydrate), and FAT's induced LH maximum concentration occurred sooner (P=.02) than CYS. We conclude that either product may be used in beef cows without compromising fertility. / Master of Science