Made available in DSpace on 2016-07-18T17:53:07Z (GMT). No. of bitstreams: 1 Dissertacao.pdf: 349806 bytes, checksum: 1fd0f5db382ba931252ba16e3de9a860 (MD5) Previous issue date: 2010-03-03 / The technique of timed artificial insemination (TAI) can be used as a tool to optimize reproductive efficiency. Among the alternative protocols hormone, prostaglandin (PGF2&#945;) and estradiol benzoate (EB) have been used frequently, or combined with progesterone and GnRH analogues. This work aimed to evaluate the influence of follicular diameter on the pregnancy rate using BE or GnRH on the placement of the implant of progesterone (D0) in beef cows divided into two groups: G-BE (n = 32) and G-GnRH (n = 29). The D0 was placed implant P4 (CIDR ®) and applied 2 ml of BE (G-BE) or 2.5 mL of GnRH (GnRH-G). In D9 the implant was removed, concomitant administration of 2.5 mL of 0.25 mL PGF2&#945; and estradiol cypionate (ECP ®) followed by removal of calves. After 48 h all the cows were inseminated and the calves returned. At D0 and D9 was held ultrasound to measure the dominant follicle (DF) present in the ovary. There was no difference (p&gt; 0.05) in pregnancy rate between treatments, BE (55%) and GnRH (41%), but the follicular diameter was significantly higher (p &lt;0.05) in pregnant cows treated with EB (10.7 mm vs. 8.5 mm) and in cows treated with GnRH there was no difference (p&gt; 0.05) between pregnant and empty (11.6 mm vs. 10.2 mm). We also evaluate the postpartum period (&gt; or &lt;45 days), the application of eCG or temporary removal of the calves (RTB) and the influence of genetic group on TAI. We used the 678 cows being: Nelore (n = 234), Nelore, Brahman (n = 159) and ¾ Nellore-Red Angus (n = 285) divided into G-Early (GP, n = 151) and G-Late (GT, n = 527). Again divided into GP-RTB (n = 93) and GT-RTB (n = 299), GP-eCG (n = 58) and GT-eCG (n = 228). The animals received CIDR ® + 2 mL of BE (D0). In D8, the device was removed and all groups received 2.5 mL PGF2&#945; &#61472;, and 1.5 mL eCG (GP-GT-eCG and eCG) or removal of calves (GP-GT-RTB and RTB). In D9 the animals received 1 mL BE and 24 hours after held IATF. The pregnancy rate did not change (p&gt; 0.05), and 40% (GP) and 48% (GT). Also did not change (p&gt; 0.05) in groups: GP-eCG (37.9%), GP-RTB (41.9%), GT-eCG (51.7%) and GT-RTB (45.1 %). The pregnancy rate in Nelore cows - Brahman (37%) was lower (p &lt;0.05) than the Nellore (52%) and ¾ Nellore Red - Angus (45%). It was concluded that the use of GnRH in D0 does not improve pregnancy rate in cows in the postpartum period, even increasing follicular diameter, which females with less than 45 days postpartum are able to IATF, regardless of the use of eCG or RTB and race influence of mothers on pregnancy rate. / A técnica da inseminação artificial em tempo fixo (IATF) pode ser utilizada como ferramenta para otimização da eficiência reprodutiva. Entre as alternativas de protocolos hormonais, a prostaglandina F2&#945; (PGF2&#945;), seus análogos e o benzoato de estradiol (BE) têm sido utilizados com freqüência, combinados à progesterona (P4) ou análogos e GnRH ou análogos. Neste trabalho objetivou-se avaliar a influência do diâmetro folicular sobre a taxa de prenhez, utilizando BE ou GnRH no dia da colocação do implante de progesterona (D0) em vacas de corte divididas em dois grupos: G-BE (n=32) e G-GnRH (n=29). No D0 foi colocado um dispositivo intravaginal de P4 (CIDR®) e aplicado 2mL de BE (G-BE) ou 2,5 mL de GnRH (G-GnRH). No D9 foi retirado o implante, concomitante à administração de 2,5 mL de PGF2&#945; e 0,25 mL de cipionato de estradiol (E.C.P.®) seguido de remoção dos bezerros. Após 48h todas as vacas foram inseminadas e os bezerros retornados. No D0 e D9 foi realizada ultrassonografia para medir o folículo dominante (FD) presente no ovário. Não houve diferença (p>0,05) na taxa de prenhez entre os tratamentos, BE (55%) e GnRH (41%). O diâmetro folicular foi significativamente maior (p<0,05) nas vacas prenhes tratadas com BE (10,7mm vs 8,5mm) e nas vacas tratadas com GnRH não houve diferença (p>0,05) entre as prenhes e vazias (11,6mm vs 10,2mm). Em outro experimento, avaliou-se o período pós-parto (> ou <45 dias), a aplicação de eCG ou remoção temporária dos bezerros (RTB) e influência do grupo genético na IATF. Utilizou-se 678 vacas sendo: Nelore (n=234), ½ Nelore-Brahman (n=159) e ¾ Nelore-Red Angus (n=285) divididas em G-Precoce (G-P, n=151) e G-Tardio (G-T, n=527). Novamente divididas em G-P-RTB (n=93) e G-T-RTB (n=299); G-P-eCG (n=58) e G-T-eCG (n=228). Os animais receberam CIDR® + 2 mL de BE (D0). No D8, o dispositivo foi retirado e todos os grupos receberam 2,5 mL PGF2&#945;&#61472;, e 1,5 mL eCG (G-P-eCG e G-T-eCG) ou remoção dos bezerros (G-P-RTB e G-T-RTB). No D9 os animais receberam 1 mL BE e 24h após realizou-se IATF. A taxa de prenhez não variou (p>0,05), sendo 40% (G-P) e 48% (G-T). Também não variou (p>0,05) nos grupos: G-P-eCG (37,9%), G-P-RTB (41,9%), G-T-eCG (51,7%) e G-T-RTB (45,1%). A taxa de prenhez nas vacas ½ Nelore Brahman (37%) foi inferior (p<0,05) que os da raça Nelore (52%) e ¾ Nelore Red Angus (45%). Foi concluído que o uso de GnRH no D0 não melhorou a taxa de prenhez em vacas no pós-parto, mesmo aumentando o diâmetro folicular, que fêmeas com menos de 45 dias pós-parto estão aptas para IATF, independente do uso de eCG ou RTB e a raça das matrizes influencia nas taxas de prenhez, sendo a raça Nelore a que apresentou a maior taxa.

Introduction : Cette thèse est issue de réflexions et d'expériences cliniques suite à un travail avec des femmes souffrant d'un trouble des conduites alimentaires (TCA) et accédant à la maternité. Dans notre recherche, parmi les différentes méthodes de Procréation Médicalement Assistée (PMA), nous avons choisi d'étudier une population ciblée : les femmes ayant recours à la pompe à la GnRH pour concevoir leurs enfants. Hypothèse principale : il existerait un grand nombre de femmes, souffrant ou ayant souffert d'un TCA, qui auraient recours à la pompe à GnRH. Hypothèse secondaire : le TCA maternel aurait des influences sur le désir d'enfant, la grossesse et les interactions précoces mère-enfant. Objectif principal : évaluer un groupe de femmes souffrant d'un TCA, enceintes après utilisation de la pompe à GnRH, à partir du 4ème mois de grossesse et jusqu'à la 8ème semaine du post-partum. Objectifs secondaires : obtenir des données scientifiques à propos des femmes souffrant d'un TCA et ayant recours à la pompe à GnRH, afin de mieux éclairer le parcours de soin de ces patientes dans les services de PMA ; obtenir des données scientifiques sur le vécu de la grossesse par les femmes TCA ; obtenir des données scientifiques sur la présence et la gravité des TCA durant la grossesse et en post-partum ; évaluer la prévalence de la dépression du postpartum chez les femmes souffrant d'un TCA. Critère d'évaluation principal : comparaison du groupe d'étude avec deux groupes témoins, l'un composé de femmes exemptes de TCA devenues enceintes par des méthodes de PMA autres que la pompe à GnRH, et l'autre composé de femmes exemptes de TCA devenues enceintes spontanément. Critères d'évaluation secondaires : évaluation de l'évolution du TCA, en pré et postnatal, par l'hétéro-questionnaire EDE ; évaluation du vécu de la grossesse par des entretiens semi-structurés ; évaluation des représentations maternelles par l'IRMAG ; évaluation de l'état psychique en pré et postnatal par l'auto-questionnaire HAD ; évaluation de l'anxiété par l'utilisation du STAI ; évaluation du risque de survenue d'une dépression du postpartum par l'auto-questionnaire EPDS. Cette étude est observationnelle et prospective : étape prénatale - 3 évaluations, entre 16 et 20 semaines d'aménorrhée (SA), entre 24 et 28 SA et entre 28 et 32 SA ; étape postnatale - 1 évaluation, à la 8ème semaine environ du postpartum. Conclusion : on constate que le TCA maternel peut être un facteur de risque en ce qui concerne la grossesse et les interactions précoces mère-bébé. L'utilisation de la pompe à GnRH par les femmes souffrant d'un TCA devrait être considéré comme un véritable enjeu de santé publique, requérant évaluation, prévention et prise en charge pluridisciplinaire de la grossesse jusqu'au post-partum. / Introduction: This thesis is the result of reflexions and clinical experiences from our work of pregnancy in women suffering from lifetime eating disorders (ED). Among different methods of assisted reprodutive technology (ART), we chose to study a special population: women seeking GnRH pulsatile administration treatment. Main hypothesis: there is an important rate of women with a lifetime ED seeking GnRH pulsatile administration treatment . Secondary hypothesis: maternal ED have influences on the desire for a child, pregnancy and early mother-child interactions. Main objective: to evaluate pregnant women with a lifetime ED after seeking GnRH pulsatile administration treatment, from the 4th month of pregnancy until the 8th week of postpartum. Secondary objectives: to obtain scientific data about women with lifetime ED seeking GnRH pulsatile administration treatment ; to better inform the multidisplinary care of these patients in the ART services ; to obtain scientific data about the experience of pregnancy in women with a lifetime ED and about the presence and severity of ED during pregnancy and postpartum ; to estimate the prevalence of postpartum depression in these women. Design: A descriptive comparative three-group design in which collected data were compared - one of women with lifetime ED who became pregnant after GnRH pulsatile administration treatment, one of women without lifetime ED who became pregnant after using other ART methods , one of women without lifetime ED who had a spontaneous pregnancy. Evaluation criteria: EDE to evaluate ED during the pre- and post-natal period ; clinical semi-structured interviews to evaluate how the pregnancy is experienced ; IRMAG to evaluate maternal representations ; HAD to evaluate anxiety and depression during the pre and postnatal period ; STAI to evaluate anxiety ; EPDS to evaluate risk of postpartum depression. This study is observational and prospective: during the prenatal period - 3 evaluations were conducted, between 16 and 20 weeks of amenorrhea (SA), between 24 and 28 SA and between 28 and 32 SA ; during the postnatal period - 1 evaluation was conducted around the 8th week. Conclusion: Eating disorders and GnRH pulsatile administration can be considered as a real public health issue, requiring strategies to address prevention, identification and multidisciplinary care for these women during pregnancy and postpartum. An eating disorder screening tool should be included in the initial intake, because these patients may be at a higher risk for negative maternal and fetal outcomes than non eating disorder patients.

No description available.

Hypothalamic gonadotropin-releasing hormone (GnRH) (GnRH I) is the central regulator of the mammalian reproductive system. Most vertebrates studied also possess a second form of GnRH, GnRH II. GnRH I acts on its cognate G proteincoupled receptor (GPCR) on pituitary gonadotropes and activates Gq/11-mediated signalling pathways to stimulate the biosynthesis and the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH). Both GnRHs have also been suggested to inhibit cellular proliferation, an action which has largely been proposed to be mediated by the coupling of the receptor to Gi/o. However, the range of G proteins activated by the GnRH receptor and the signalling cascades involved in inducing antiproliferation remain controversial. To delineate the G protein coupling selectivity of the mammalian GnRH receptor and to identify the signalling pathways involved in GnRH I-mediated cell growth inhibition, I examined the ability of the receptor to interact with Gq/11, Gi/o and Gs in Gαq/11 knockout MEF cells. My results indicate that the receptor is unable to interact with Gi/o but can signal through Gq/11. Additionally, my data do not support the suggestion of GnRH receptor-Gs interaction. Furthermore, I show that the GnRH Iinduced inhibition of cell growth is dependent on Gq/11, src and extracellular signal regulated kinase (ERK) but is independent of the activity of protein kinase C (PKC), Ca2+, jun-N-terminal kinase (JNK) or P38. Based on these findings and previous research within our group, I propose a mechanism whereby GnRH I may induce antiproliferation. Previous studies from our laboratory suggest that the GnRH receptor can adopt distinct active conformations in response to the binding of GnRH I and GnRH II. These data thus account for our hypothesis of ligand-induced selective signalling (LiSS). Given my previous results, I examined the ability of the GnRH receptor to couple to G12/13. My work indicates that the receptor can directly activate G12/13 and the downstream signalling cascades associated with this G protein family. Indeed, I provide evidence, in several cellular backgrounds, to suggest that GnRH receptor- G12/13-mediated signalling is involved in the regulation of GnRH-induced MAPK activity, SRE-driven gene transcription and cytoskeletal reorganisation. Furthermore, I propose a role for these G proteins in the transcriptional regulation of LHβ and FSHβ. Finally, I confirm previous results from our laboratory indicating that the GnRH receptor may interact with src Tyr kinase and show that GnRH I but not GnRH II may, independently of Gq/11, stimulate the Tyr phosphorylation and thus the activation of this protein. I propose that this differential signalling accounts for the distinct effects of GnRH I and GnRH II on cellular morphology and SREpromoted transcriptional activity. The research presented within this thesis provides evidence to refute published conclusions based on largely circumstantial experimental data, describes novel GnRH receptor signalling pathways and offers support for the concept of LiSS. It may assist in the development of new therapeutic compounds which selectively target one GnRH-mediated signalling pathway while bypassing others.

<p>In perifusion cell cultures, the culture medium flows continuously through a chamber containing immobilized cells and the effluent is collected at the end. In our main applications, gonadotropin releasing hormone (GnRH) or oxytocin is introduced into the chamber as the input. They stimulate the cells to secrete luteinizing hormone (LH), which is collected in the effluent. To relate the effluent LH concentration to the cellular processes producing it, we develop and analyze a mathematical model consisting of coupled partial differential equations describing the intracellular signaling and the movement of substances in the cell chamber. We analyze three different data sets and give cellular mechanisms that explain the data. Our model indicates that two negative feedback loops, one fast and one slow, are needed to explain the data and we give their biological bases. We demonstrate that different LH outcomes in oxytocin and GnRH stimulations might originate from different receptor dynamics. We analyze the model to understand the influence of parameters, like the rate of the medium flow or the fraction collection time, on the experimental outcomes. We investigate how the rate of binding and dissociation of the input hormone to and from its receptor influence its movement down the chamber. Finally, we formulate and analyze simpler models that allow us to predict the distortion of a square pulse due to hormone-receptor interactions and to estimate parameters using perifusion data. We show that in the limit of high binding and dissociation the square pulse moves as a diffusing Gaussian and in this limit the biological parameters can be estimated.</p> / Dissertation

Sendo o GnRH a molécula capaz de iniciar a cascata hormonal reprodutiva, realizamos a clonagem, analisamos os efeitos da indução à reprodução e as funções dos GnRHs de A. altiparanae. Como resultados, obtivemos as sequências dos cDNAs do GnRH2 e GnRH3. Quando induzidos à reprodução, a desova foi às 20 h pós-estímulo (hpe) em fêmeas e às 16 hpe em machos, o aumento da expressão do mRNA de GnRH3 ocorreu às 8 hpe em fêmeas, e o aumento da expressão do mRNA de GnRH2 foi às 0 hpe em machos. Com relação ao efeito dos GnRHs, todos estimularam a expressão do mRNA de &beta;LH, mas não de &beta;FSH, e só o GnRH2 foi capaz de elevar o MIS e causar a desova. Como conclusão, temos que as sequências dos cDNAs dos GnRHs se mostraram conservadas; a indução à reprodução por redução do nível da água foi eficaz; em cativeiro, a espécie teve desenvolvimento assincrônico; o GnRH2 provavelmente está ligado ao comportamento reprodutivo, e o GnRH3 é a possível forma hipofisiotrópica. Por fim, só o GnRH2 desencadeou toda a cascata hormonal. / The study on reproduction in fish has been acquired great importance in last years, mainly for the benefit of threatened species. During the reproductive process, the hypothalamic neurons synthesize and release GnRH that stimulates the pituitary cells to release FSH and LH, which, in turn, promote the gonadal maturation. In fact, the morphological changes in gonads are the result of the endocrine action of the reproductive axis, in which the GnRH is the key molecule to starting the reproductive axis control. Thus, the knowledge about the GnRH, as well as about the gonadal morphological changes in the spawning might contribute to effectiveness of reproduction. Therefore, in this work, with Astyanax altiparanae as a model, we made the molecular characterization of the GnRHs, and we analyzed the gonadal morphological changes during the reproductive stimulus. In addition, we evaluated the role of injected GnRHs in vivo. As results, we obtain the cDNA complete sequence of preproGnRH2 (612bp) and preproGnRH3 (407bp) of A. altiparanae. Regarding the induction of reproduction by water level drawdown, the released of gametes occurred at 20 hours after stimulus in female and at 16 hours after stimulus in males, the mRNA expression of GnRH3 increased at 8 hours after stimulus in female and the mRNA expression of GnRH2 increased at 0 hours in males. Regarding the effects of injected GnRH, all of them stimulated the &beta;LH but not &beta;FSH mRNA expression, and only the GnRH2 was able to rise the MIS and stimulate the released of gametes. We conclude that the cDNAs sequences of preproGnRH2 and preproGnRH3 were conserved, although there is a change in the amino acid at the position 8 of the GnRH3 decapeptide of A. altiparanae. Furthermore, the induced reproduction by water level drawdown was effective, and in captivity, the A. altiparanae has an asynchronous development with splitted spawning during the breeding season. The analysis of the animals submitted to the reproductive stimulus allowed us to suggest that in A. altiparanae, the GnRH2 probably has a role in sexual behavior and the GnRH3 possibly is the hypophysiotropic form. Finally, analyzing the GnRH effects, we observed that only the GnRH2 was able to start the entire reproductive hormonal cascade, leading the animal to spawning.

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No. of bitstreams: 2 dissertacao_livia_budziarek_eslabao.pdf: 1788001 bytes, checksum: c14f927ac7e6babdc2bd66cf80275556 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A imunocontracepção é reconhecida como um dos principais novos métodos contraceptivos para o controle e o manejo da fertilidade em diferentes espécies animais. Dentre os potenciais alvos utilizados em vacinas contraceptivas, o hormônio liberador de gonadotrofinas (GnRH) é considerado um dos mais atrativos. O GnRH é um decapeptídeo hipotalâmico que apresenta um papel central na reprodução de mamíferos. Entretanto, devido à sua baixa imunogenicidade, é necessário associar o GnRH com uma molécula carreadora capaz de estimular o sistema imune como, por exemplo, a subunidade B da enterotoxina termolábil de Escherichia coli (LTB). O presente estudo visou avaliar o potencial imunocontraceptivo de duas quimeras LTB/GnRH em camundongos machos da linhagem BALB/c. Os camundongos foram divididos aleatoriamente em oito grupos experimentais. O grupo LTB/GnRH-P recebeu a quimera expressa em P. pastoris. O grupo LTB/GnRH-P/A recebeu a quimera expressa em P. pastoris adsorvida em adjuvante oleoso. O grupo LTB/GnRH-E recebeu a quimera expressa em E. coli. O grupo LTB/GnRH-E/A recebeu a quimera expressa em E. coli adsorvida em adjuvante oleoso. O grupo LTB recebeu a proteína LTB expressa em E. coli. Os grupos Controle e Controle/A não receberam nenhum antígeno vacinal. O grupo Vacina comercial recebeu vacina comercial anti-GnRH utilizada em bovinos. A resposta imune humoral foi avaliada pela técnica de ELISA indireto e o potencial imunocontraceptivo foi avaliado por meio da quantificação de testosterona sérica e das análises histológicas das gônadas dos animais. Os grupos que receberam os antígenos LTB/GnRH (25 μg por vacina) apresentaram níveis de IgG total significativamente superiores quando comparados aos grupos controle, mostrando que ambos os antígenos são imunogênicos. Os grupos LTB/GnRH-P e LTB/GnRH-P/A apresentaram as maiores absorbâncias nos dias 28 (1,11 ± 0,09) e 42 (1,44 ± 0,04), respectivamente. Além disso, o grupo LTB/GnRH-P/A apresentou níveis de testosterona significativamente menores ao controle a partir do dia 28 (192 ng/dl ± 254,55). Os grupos LTB/GnRH-E e LTB/GnRH-E/A também obtiveram os maiores níveis de anticorpos nos dias 28 (0,33 ± 0,005) e 42 (1,44 ± 0,08), respectivamente. O grupo LTB/GnRH-E/A apresentou níveis de testosterona significativamente menores ao controle a partir do dia 28 (<12 ng/dl ± 0). Os resultados da histologia mostraram que ambos os antígenos causam alterações na espermatogênese, sendo que o antígeno expresso em E. coli foi relacionado com as maiores alterações nas gônadas. O presente estudo mostrou quimeras produzidas através da fusão da LTB com uma única molécula de GnRH é capaz de induzir a geração de resposta imune humoral, bloqueio das funções endócrinas relacionadas com a reprodução e alterações teciduais nas gônadas de camundongos machos. / Immunocontraception is recognized as one of the major new contraceptive methods for the control and management of fertility in different animal species. Among the potential targets used in contraceptive vaccines, gonadotropin-releasing hormone (GnRH) is considered one of the most attractive. GnRH is a hypothalamic decapeptide that presents a central role in mammalian reproduction. However, due to its low immunogenicity, it is necessary to associate the GnRH with a carrier molecule capable of stimulating the immune system such as, for example, the B subunit of Escherichia coli heat-labile enterotoxin (LTB). The present study aimed to evaluate the immunocontraceptive potential of two LTB/GnRH chimeras in male BALB/c mice. Mice were randomly divided into eight experimental groups. The LTB/GnRH-P group received the chimera expressed in P. pastoris. The LTB/GnRH-P/A group received the chimera expressed in P. pastoris adsorbed in oil adjuvant. The LTB/GnRH-E group received the chimera expressed in E. coli. The LTB/GnRH-E/A group received the chimera expressed in E. coli adsorbed in oil adjuvant. The Control and Control/A groups did not receive vaccine antigen. The Commercial vaccine group received an anti-GnRH commercial vaccine used in cattle. The humoral immune response was evaluated by indirect ELISA and the immunocontraceptive potential was assessed through the quantification of serum testosterone and the histological analysis of animal’s gonads. The groups that received LTB/GnRH antigens (25 μg per vaccine) presented total IgG levels significantly higher when compared to the control groups, showing that both antigens are immunogenic. The LTB/GnRH-P and LTB/GnRH-P/A groups showed higher absorbances at days 28 (1,11 ± 0,09) and 42 (1,44 ± 0,04), respectively. Furthermore, the LTB/GnRH-P/A group presented testosterone levels significantly lower to the control from day 28 (192 ng/dl ± 254,55). The LTB/GnRH-E and LTB/GnRH-E/A groups also obtained the highest antibody levels at days 28 (0,33 ± 0,005) and 42 (1,44 ± 0,08), respectively. The LTB/GnRH-E/A group presented testosterone levels significantly lower to the control from day 28 (<12 ng/dl ± 0). The results from histology showed that both antigens cause changes in spermatogenesis, wherein the antigen expressed in E. coli was associated with major changes in gonads. The present study showed that chimeras produced through the merge of LTB with a single GnRH molecule is capable to induce the generation of humoral immune response, block of the endocrine functions related to reproduction, and tissue alterations in the gonads of male mice.

O objetivo, deste estudo foi investigar o comportamento dos hormônios esteróides 17β-Estradiol (E2), 17α-hidroxiprogesterona (17α-OHP), Testosterona (T) e 11-Ketotestosterona (11-KT), em piracanjuba Brycon orbignyanus de diferentes sexos e idades, na estação reprodutiva, e nas fêmeas submetidas à reprodução induzida. Os animais utilizados no trabalho, eram criados em piscicultura comercial, mantidos em 3 viveiros, separados por lotes de diferentes idades. A coleta dos animais, consistiu de quatro machos e cinco fêmeas (48 meses), identificados através do dimorfismo sexual da espécie, e as demais idades, (12 e 24 meses), coletaram-se, 20 peixes de cada idade, para identificação do sexo através de histologia. Já o experimento de caracterização dos esteróides sexuais na reprodução induzida, foram coletadas cinco fêmeas, selecionadas através das características com: abdome abaulado, papila urogenital, saliente e avermelhada. Após captura, os peixes foram transportados ao laboratório, onde houve coleta de sangue, para quantificação do perfil plasmático de E2, 17α-OHP, T e 11-KT. Posteriormente, os animais foram abatidos e suas gônadas coletadas e fixadas, a fim de que fosse realizada análise histológica para identificação do sexo. Na reprodução induzida, foi coletado sangue em dois momentos: pré-indução (PI) e pós-extrusão (PE). O nível plasmático de E2 nos machos de 12 meses destaca sua ação no processo de proliferação e renovação das espermatogônia observado em machos imaturos. Nas fêmeas o E2 apresentou os maiores níveis (P<0,05) nos animais de 48 meses, confirmando assim, sua principal função na estimulação do processo de vitelogênese, e maturação final do oócito. Quanto aos andrógenos T e 11-KT, os maiores níveis (p<0,05) foram observados nos peixes adultos (48 meses), permitindo afirmar que estes atuam como feedback negativo, do FSH e feedback positivo do LH, fundamental no processo de maturação final e liberação dos gametas, além de regular o comportamento reprodutivo. O resultado da 17α-OHP, sugere que, nas idades estudadas, é indispensável por participar como precursor dos principais esteróides (T, E2 e 11-KT), além da 17α,20β dihydroxy-4-pregnen-3-one (17α,20β-DHP), essencial no estágio final de maturação, e desova na reprodução induzida. / The objective of this study was to investigate the physiological behavior of steroid hormones 17β-Estradiol (E2), 17α-hydroxyprogesterone (17α-OHP), testosterone (T) and 11-Ketotestosterone (11-KT) in Brycon orbignyanus with different sex and ages on the reproductive season and in females submitted to induced reproduction. The animals used in the study were kept in three ponds on a commercial fish farming, separated by lots with different ages. The sampling of animals consisted of the collection of four males and five females (48 months) identified by the sexual dimorphism of the specie. In the other groups (12 and 24 months), 20 fish of each age were collected for identification of sex through histology. In the experiment with characterization of the sexual steroids in the induced reproduction, were collected five females selected through the following characteristics: bulging abdomen and prominent reddish genital papilla. After capture, the fish were transported to the laboratory, where blood was collected for quantification of the plasma profile of E2, 17α-OHP, T and 11-KT Subsequently, the animals were slaughtered and their gonads were collected and fixed for histological analysis. In the induced females, blood was collected at two moments: pre-induction (PI) and post-extrusion (PE). The plasma profile of E2 is fundamental in immature males, highlighting its action in the process of proliferation and renewal of spermatogonia, observed in males of 12 months. In females E2 presented the highest levels (P <0.05) in animals at 48 months, thus confirming its main function in the stimulation of the vitellogenesis process and final oocyte maturation. The highest levels (p <0.05) of T and 11-KT androgens were observed in adult fish (48 months), allowing to affirm that they are acting as FSH negative feedback and LH positive feedback, fundamental in the final maturation and release of the gametes, besides regulating the reproductive behavior of the fish. The results of 17α-OHP suggest this hormon is fundamental in the studied ages because it is a precursor of the main steroids (T, E2 and 11-KT) and 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-DHP), essential in the final stage of maturation and spawning in induced reproduction.

Les perturbateurs endocriniens (PE) sont une préoccupation majeure de par leurs effets sur les grandes fonctions physiologiques des organismes etparticulièrement sur la fonction de reproduction. Chez les vertébrés, la reproduction est sous le contrôle d’un axe neuroendocrinien nommé axegonadotrope. Celui-ci comprend différents acteurs cérébraux (gonadolibérines et kisspeptines), hypophysaires (gonadotropines) et gonadiques(stéroïdes sexuels) dont la mise en place et le fonctionnement sont régulés finement. Parmi les mécanismes de régulation, les stéroïdes vont jouer unrôle important en effectuant des boucles de rétrocontrôle. Les PE mimant ces stéroïdes sont donc potentiellement capables d’impacter ces régulations.L’objectif de ce travail était d’évaluer les effets d’un xénooestrogène sur les mises en place des acteurs cérébraux impliqués dans l’axe gonadotrope chezle bar européen (Dicentrarchus labrax). Nous avons d’abord décrit l’ontogénèse des systèmes à kisspeptine, à gonadolibérine et à gonadotropine aucours du développement larvaire. Nous avons mis en évidence une régulation différentielle de ces acteurs suggérant un rôle durant ce processusdéveloppemental. De plus, nous montrons que le 17α-éthinylestradiol (EE2) est capable de perturber l'ontogenèse des systèmes à GnRH2 et à GnRH3au cours des stades précoces du développement larvaire.Ces données constituent une base permettant l’évaluation des effets des PE sur l’ontogénèse des systèmes neuroendocriniens. / Endocrine disruptors (EDs) are a major concern because of their effects on the main physiological functions, particularly on the reproductive function.In vertebrates, reproduction is under the control of a neuroendocrine axis called hypothalamic-pituitary-gonadal (HPG) axis. It includes various actors atthe brain (gonadotropin releasing hormones (GnRH) and kisspeptins), pituitary (gonadotropic hormones) and gonadal (sex steroids) levels. Theirdévelopment and functioning are finely regulated. Among the regulators, steroids play an important role by performing feedback loops. EDs mimickingsteroids are therefore potentially able to impact these regulations. The objective of this work was to evaluate the effects of xenoestrogens on theimplementation of cerebral actors involved in the HPG axis in the European sea bass (Dicentrarchus labrax). We first described the ontogeny of thekisspeptin, GnRH and gonadotropin systems during larval development. We have highlighted a differential regulation of these actors suggesting a roleduring this developmental process. In addition, we show that 17α-ethinylestradiol (EE2) is able to disrupt the ontogeny of GnRH2 and GnRH3 systemsduring the early stages of larval development.These data provide a basis for evaluation of the EDs effects on the ontogeny of neuroendocrine systems.

Several studies suggest that the administration of GnRH near the time of insemination improves pregnancy rates in cattle. It has also been reported that there is greater improvement in repeat-breeder animals than at first service. The mechanism for this observation has not been established. Twenty-eight lactating Holstein cows that returned to estrus after one or more inseminations from the usu caine Dairy were used in the study. Anilrals were rarxiomly divide:i into tW'O treatment groups, intrarmJscular administration of 100 ug GnRH or saline oontrol at the tirre of insemination. Blood samples were collected at o, 1, 1.5, 2, 2.5, 3 and 4 hours post-insemination for LH determination and on days 0 through 7, 10, 16 and 22 for progesterone determination. Pregnancy status was detennined by rectal palpation 40 to 47 days post insemination. serum IR concentrations reached peak concentrations (9.33 ± 5.5 ng/ml) by one hour following GnRH administration. This was significantly different from saline controls (p Serum progesterone levels increased as expected. from day o to day 16 in all animals. Animals treated with GnRH that became pregnant tended to have the highest progesterone levels beginning from day 4. Animals treated with GnRH that were non-pregnant at 40 to 47 days tended to have the lowest progesterone levels from days 4 through 10 but were high on day 16. Pregnant animals had higher progesterone levels than non-pregnant animals from days 4 to 16. These differences approached significance (0.25 > p < 0.10). These results support the contention that GnRH administration affects progesterone levels rut do not conclusively establish increased early progesterone levels as the mechanism for improved pregnancy rates. Other hormonal andl functional factors may be involved.