Conselho Nacional de Desenvolvimento Científico e Tecnológico / Nitric oxide (NO) is an important regulator of ovarian activity, and is produced by a family of nitric oxide synthases (NOS), being inducible (iNOS) and endothelial (eNOS) isoforms present in the ovaries of several species. In cows, even though NO production had been demonstrated in follicular fluid and by granulosa cells (GC) cultured in vitro, it is not known which enzyme is responsible for NO synthesis or how expression is regulated during follicular development. The objectives of the present study were to determine the abundance of iNOS and eNOS mRNAs in dominant and subordinate follicles in vivo, to determine the regulation of iNOS expression by FSH, growth factors and estradiol (E2) in vitro, to stimulate NO production in bovine CG and to determine the action of iNOS on bovine granulosa cell health/apoptosis. The two largest follicles on days 1 to 5 of the first follicular wave of the cycle were collected from each pair of ovaries from six cows. Dominant follicles presented higher levels of mRNA for iNOS compared to subordinate follicles (P<0.01). GC cultures were performed with ovaries collected at abattoir. FSH (P<0.05) and IGF1 (P<0.01) stimulated E2 secretion and upregulated iNOS mRNA abundance in a dose-dependent manner. Moreover, both FGF2 (P<0.05) and EGF (P<0.01) decreased iNOS expression and E2 secretion in FSH and IGF-treated cells, respectively. Graded doses of FSH in the presence of a non-aromatizable androgen (DHT) did not stimulate iNOS mRNA level. In addition, both FSH and IGF1 in the presence of an estrogen receptor antagonist were not able to upregulate iNOS mRNA abundance, whereas E2 alone stimulated NO production in vitro. In terms of cell health/apoptosis, the treatment with an iNOS-selective inhibitor increased the pro-apoptotic factor FasL mRNA levels and the percentage of dead cells (P<0.05). In conclusion, bovine granulosa cells express predominantly iNOS, and increased iNOS mRNA levels are associated with emergence of the dominant follicle. FSH and IGF1 stimulate iNOS mRNA levels through increased E2 secretion, and physiological levels of NOS activity may contribute to growth and survival of bovine granulosa cells. / O óxido nítrico (NO) é um importante regulador da atividade ovariana que é produzido a partir da ação de uma família de enzimas denominadas sintases do óxido nítrico (NOS). As isoformas induzível (iNOS) e endotelial (eNOS) estão presentes nos ovários de diversas espécies. Em vacas, embora a produção de NO já tenha sido detectada no fluído folicular e também no meio de cultivo de células da granulosa (CG), não se sabe qual enzima é responsável pela síntese de NO nem como ocorre a regulação de sua expressão ao longo do desenvolvimento folicular. Os objetivos do presente estudo foram determinar a abundância de RNAm para iNOS e eNOS em CG provenientes de folículos dominantes e subordinados in vivo; determinar a regulação da expressão da iNOS por FSH, fatores de crescimento e estradiol (E2) in vitro; estimular a produção de NO e determinar a ação da iNOS na relação entre saúde e apoptose das CG bovina. Foram coletados os dois maiores folículos presentes em cada par de ovários de seis vacas entre os dias 1 e 5 da primeira onda folicular do ciclo estral. Folículos dominantes apresentaram níveis mais elevados de RNAm para iNOS comparados aos folículos subordinados (P<0.01). Cultivos de CG foram realizados com ovários coletados em abatedouro. Ambos FSH (P<0.05) e IGF1 (P<0.01) estimularam a secreção de E2 e a expressão de iNOS de maneira dose-dependente. Além disso, tanto FGF2 (P<0.05) como EGF (P<0.01) diminuiram a expressão de iNOS e a secreção de E2 em células tratadas com FSH e IGF1, respectivamente. Utilizando diferentes doses de FSH na presença de um andrógeno não-aromatizável (DHT), não foi possível estimular a expressão de iNOS. Ainda, tanto o FSH como o IGF1 não foram capazes de elevar a abundância de RNAm para iNOS na presença de um antagonista não seletivo dos receptores de E2, enquanto que, E2 sozinho estimulou a produção de NO em CG in vitro. No que diz respeito à relação saúde/apoptose das CG, o tratamento com um inibidor seletivo da iNOS aumentou os níveis de RNAm para o fator pró-apoptótico FasL e o percentual de células mortas (P<0.05). Concluindo, células da granulosa bovina expressam predominantemente iNOS, sendo que o aumento da expressão dessa isoforma está associado com a emergência do folículo dominante. FSH e IGF1 promovem o aumento dos níveis de RNAm para a iNOS através do estímulo da secreção de E2 e, níveis fisiológicos da atividade das NOS podem contribuir para o crescimento e sobrevivência das células da granulosa bovina.

Fxrα est le récepteur nucléaire des acides biliaires, exprimé majoritairement dans le foie, l'intestin, les reins et les glandes surrénales. L'intérêt pour ce dernier est devenu croissant au cours des dernières années, de part le rôle central qu'il joue dans le contrôle de l'homéostasie du cholestérol, des acides biliaires, des triglycérides ou encore du glucose. Plus récemment, Fxrα ainsi que ses ligands, les acides biliaires, ont été localisés dans le testicule, soulevant la question du rôle potentiel de Fxrα dans cet organe, et plus généralement dans la fonction de reproduction mâle. Mais les études menées à ce sujet restent jusqu'à présent peu nombreuses, et focalisées sur son implication dans le contrôle du métabolisme des stéroïdes : l'activation in vivo de Fxrα par un agoniste synthétique conduit ainsi chez l'adulte à court terme à une répression de la stéroïdogenèse. Outre son rôle dans le contrôle de l'activité endocrine des cellules de Leydig, l'impact de l'activation in vivo de Fxrα sur la physiologie plus globale du testicule n'a jamais été abordé à ce jour. De telles études seraient pourtant pertinentes étant donné que Fxrα est ciblé pour le traitement de pathologies métaboliques telles que la dyslipidémie ou le diabète. Dans ce contexte, l'objectif de ce travail de thèse était d'étudier le rôle de Fxrα dans la physiologie et la pathophysiologie du testicule, en s'appuyant sur l'analyse d'un modèle murin dont le gène codant Fxrα a été invalidé. Nos résultats démontrent que : 1) la perte de Fxrα prédispose le testicule à une sur-mortalité des cellules germinales dans un contexte pathologique de cholestase ; 2) la sur-activation de la signalisation Fxrα au cours de la puberté conduit à un défaut de la différenciation germinale, associée à une altération de la fonction endocrine du testicule ; 3) outre la régulation de la stéroïdogenèse dans les cellules de Leydig, Fxrα participe au contrôle des fonctions sertoliennes et de la prolifération et / ou différenciation des cellules germinales souches. L'ensemble de ces données définissent Fxrα comme un nouvel acteur impliqué dans le contrôle de la physiologie testiculaire et devraient être prises en considération quant-à l'utilisation de molécules agonistes et / ou antagonistes de Fxrα dans le cadre du traitement de pathologies métaboliques. / Fxrα is the bile acid nuclear receptor, predominantly expressed in liver, intestine, kidney and adrenal glands. In recent years, interest in Fxrα has been increasing due to its central role in the control of cholesterol, bile acids, triglycerides or glucose homeostasis. More recently, Fxrα and its ligands, bile acids, have been detected in the testis pointing out its potential involvement in this tissue and more widely in the male reproductive functions. However, the few studies on this topic focused essentially on Fxrα involvement in the control of steroids metabolism. Indeed, activation of Fxrα in vivo with a synthetic agonist leads to short-term steroidogenesis repression in the adult. In vivo the impact of alteration of Fxrα signaling on the global testis physiology has never been explored so far. Such studies would be pertinent considering that Fxrα is a target for the treatment of metabolic diseases such as dyslipidemia or diabetes. In this context, the aim of my work was to study the implication of Fxrα in testis physiology and physiopathology by analyzing a knock out mouse model for Fxrα. Our results show that: 1) the loss of Fxrα increase germ cell mortality in the testis in a disease context of cholestasis ; 2) over-activation of Fxrα signaling during puberty leads to germ cell differentiation defects, associated with an alteration of testis endocrine function ; 3) besides steroidogenesis control in Leydig cell, Fxrα is involved in Sertoli cell functions and spermatogonial stem cell proliferation and/or differentiation. Taken together, these data define Fxrα as a new actor involved in the control of testis physiology, and should be taken into consideration regarding the use of Fxrα agonistic or antagonistic ligands for the treatment of metabolic diseases.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-04T17:40:43Z No. of bitstreams: 1 sabinewohlresviana.pdf: 8250469 bytes, checksum: d5749466ebaf01dd23c74317cbef4a6a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-07T03:23:30Z (GMT) No. of bitstreams: 1 sabinewohlresviana.pdf: 8250469 bytes, checksum: d5749466ebaf01dd23c74317cbef4a6a (MD5) / Made available in DSpace on 2015-12-07T03:23:30Z (GMT). No. of bitstreams: 1 sabinewohlresviana.pdf: 8250469 bytes, checksum: d5749466ebaf01dd23c74317cbef4a6a (MD5) Previous issue date: 2015-01-27 / O objetivo geral deste estudo foi investigar variações genômicas e transcriptômicas do receptor de hormônio luteinizante (LHR) e seu papel nos processos de dominância folicular e resposta à superovulação em bovinos. Foram realizados três experimentos, sendo que em todos se utilizou cDNA sintetizado a partir do RNA total extraído de células da granulosa (CG) folicular. Para a caracterização do transcrito do LHR, CG foram recuperadas de folículos dominantes de vacas das raças Gir (n=16) e Holandês (n=16). Após a PCR e o sequenciamento, os dados foram analisados para a presença de polimorfismos, frequência alélica, conteúdo de informação polimórfica (PIC) e Equilíbrio de Hardy-Weinberg (HWE). Vinte e um polimorfismos de base única (SNPs) foram identificados, sendo 17 em Gir e 14 em Holandês. A classificação dos SNPs de acordo com os valores de PIC identificou 12 como altamente informativos em Gir e cinco em Holandês. Em relação a HWE, oito SNPs não estavam em equilíbrio em Gir e 10 em Holandês. Duas isoformas derivadas de splicing alternativo também foram identificadas, uma no éxon 1 e outra no éxon 10. Conclui-se que o LHR em bovinos leiteiros apresenta uma alta frequência de polimorfismos e múltiplas isoformas. Para avaliar o papel das isoformas do LHR nas CG durante a divergência folicular, a emergência da onda folicular foi sincronizada em novilhas Gir (n=10) e Holandês (n=10) e os folículos foram aspirados individualmente em diâmetros correspondentes aos períodos de pré-divergência, divergência, e pós-divergência. A expressão relativa das isoformas de LHR foi determinada por PCR em Tempo Real e os resultados foram relacionados com as concentrações intrafoliculares de estradiol (E2if). Em ambas as raças, houve um aumento progressivo na concentração de E2if ao longo do desenvolvimento folicular. O E2if foi maior em Holandês quando comparado com Gir antes, durante, e depois da divergência; mas foi similar em folículos de mesmo diâmetro nas duas raças. Observou-se um pico de expressão de LHR total após o início da divergência folicular. A expressão das isoformas de LHR foi ou baixa (Holandês) ou sub-regulada (Gir) durante este mesmo período. Os resultados sugerem que a divergência precoce do folículo dominante em raças de Bos indicus podem estar relacionados à maior sensibilidade ao feedback negativo do estradiol. Além disso, mudanças sequenciais na expressão das isoformas de LHR podem regular a função do LHR durante da divergência folicular em bovinos. A avaliação do comportamento das isoformas de LHR durante a indução exógena do crescimento folicular foi realizada em novilhas Gir caracterizadas com boa (n=5) ou má (n=5) resposta à superovulação. Em ambos os grupos, foram coletadas CG de folículos (8 mm) cujo crescimento ocorreu sem (Controle) ou com estimulação por FSH (SOV). No grupo de boa resposta, não houve diferença na expressão de LHR total entre os tratamentos Controle e SOV. No grupo de má resposta, a expressão de LHR total foi menor em SOV comparado com Controle, mas não houve diferença na expressão das isoformas. Conclui-se que o LHR é diferencialmente expresso em folículos dominantes de novilhas caracterizadas com boa ou má resposta a superovulação. / The aim of this study was to evaluate genomic and transcriptomic variations at the luteinizing hormone receptor (LHR) and its role at the follicular dominance establishment and superovulation outcome in bovine. Three experiments were performed, and for all evaluations cDNA synthesized from total RNA extracted from follicular granulosa cells (GC) were used. To characterize the LHR transcript, GC were recovered from dominant follicles from Gir (n=16) and Holstein (n=16) cows. After PCR and sequencing, data were analized to identify polymorphisms, allelic frequency, polymorphic information content (PIC) and Hardy-Weinberg Equilibrium (HWE). Twenty one single nucleotide polymorphism (SNP) were identified, being 17 in Gir and 14 in Holstein. The classification of SNP according to PIC values identified 12 as highly informative in Gir and five in Holstein. Considering HWE, eight SNP were not in equilibrium in Gir and 10 in Holstein. Two isoforms were also identified, one in exon 1 and other in exon 10. We concluded that LHR in dairy cattle shows a high frequency of polymorphism and multiple isoforms. To evaluate the LHR isoforms role in GC during follicular divergence, the follicular wave emergence was synchronized in Gir (n=10) and Holstein (n=10) heifers and follicles were individually aspirated at the corresponding sizes of pre-, divergence, and post-. The relative expression of LHR isoforms was determined by real time PCR and results were correlated to the intrafollicular estradiol (E2if) concentrations. In both breeds, there was a progressive increase in E2if concentration during follicular development. The E2if in Holstein was higher when compared to Gir before, during, and after divergence; but was similar in follicles of same size in both breeds. We observed a peak for the total LHR expression after the beginning of the follicular divergence. The expression of LHR isoforms was low (Holstein) or under-regulated (Gir) during this same period. The results suggest that the early follicular divergence of the dominat follicle in Bos indicus breeds can be related to a higher sensitivity to the estradiol negative feedback. Besides, sequential changes in LHR isoforms expression can act regulating the LHR function during folicullar divergence in bovine. The evaluation of LHR isoforms behavior during the exogenous induction of follcilualr development was performed in Gir heifer previously characterized as good (n=5) or poor (n=5) responders to superovulation. In both groups, GC were collected from follicles (8 mm) which growth occurred without (Control) or with FSH stimulation (SOV). In good responders group, there was no difference in the LHR expression between the Control and SOV treatments. In the poor responders group, the total LHR expression was lower in SOV when compared to Control, but there was no difference in the expression of the isoforms. We concluded that LHR is differentially expressed in dominant follicles from heifers characterized as good or poor responders to superovulation.

Submitted by Michele Mologni (mologni@unoeste.br) on 2018-11-30T12:45:47Z No. of bitstreams: 1 Marina Platzeck Chaves.pdf: 891914 bytes, checksum: 43d527b64ad46e92f25496042406c5e9 (MD5) / Made available in DSpace on 2018-11-30T12:45:47Z (GMT). No. of bitstreams: 1 Marina Platzeck Chaves.pdf: 891914 bytes, checksum: 43d527b64ad46e92f25496042406c5e9 (MD5) Previous issue date: 2018-05-30 / Steroids and gonadotrophins are essential for the regulation of antral follicular development and the late stages of preantral development. Although the luteinizing hormone receptor (LHR) has been detected in the preantral follicles of rats, rabbits, and pigs, the expression of this receptor in bovine fetal ovary has not been demonstrated. The present study aimed to quantify the expression of the LHR and the mRNA abundance of the genes LHR binding protein (LRBP), STAR, HSD3B1, CYP17A1, and CYP19A1 during the development of bovine fetal ovary. In addition, we aimed to identify and quantify the expression of bta-miR-222 (a regulatory microRNA of the LHCGR gene). In summary, LHR expression was observed in the preantral follicle in bovine fetal ovary, from oogonias to primordial, primary and secondary stages, and the mRNA abundance was lower on day 150 than day 60. However, the mRNA abundance of LRBP followed the opposite pattern. The LHR protein was detected in oogonia, primordial, primary, and secondary follicles. Moreover, both oocytes and granulosa cells showed positive immunostaining for LHR. Similar to LRBP, the abundance of bta-miR-222 was higher on day 150 than day 60 or 90 of gestation. With regard to the gene expression of steroidogenic enzymes; only the mRNA abundance of STAR was higher on day 150 than on day 60. In conclusion, these results suggested the involvement of LHCGR/LRBP regulation with mechanisms related to the development of preantral follicles, especially during the establishment of secondary follicles. Furthermore, the present data reinforced that the reduced expression of LHR mRNA in bovine fetal ovaries on day 150 was related to the higher expression of LRBP and bta-miR-222. / Esteroides e gonadotrofinas são essenciais para a regulação do desenvolvimento folicular antral e os estágios finais do desenvolvimento pré-antral. Embora o receptor do hormônio luteinizante (LHR) tenha sido detectado nos folículos pré-antrais de ratos, coelhos e porcos, a expressão deste receptor no ovário fetal bovino não foi demonstrada. O presente estudo teve como objetivo quantificar a expressão do LHR e a abundância de mRNA da proteína de ligação LHR (LRBP), STAR, HSD3B1, CYP17A1 e CYP19A1 durante o desenvolvimento do ovário fetal bovino. Além disso, objetivamos identificar e quantificar a expressão de bta-miR-222 (microRNA regulador do gene LHCGR). Em resumo, a expressão de LHR foi observada no folículo pré-antral no ovário fetal de bovino e a abundância de mRNA foi menor no dia 150 do que no dia 60. No entanto, a abundância de mRNA da LRBP seguiu o padrão oposto. Semelhante a LRBP, a abundância de bta-miR-222 foi maior no dia 150 do que no dia 60 ou 90. Com relação à expressão gênica de enzimas esteroidogênicas; apenas a abundância de mRNA de STAR foi maior no dia 150 do que no dia 60. A proteína LHR foi detectada em oogônia, folículos primordiais, primários e secundários. Além disso, ambos os oócitos e células da granulosa apresentaram imunolocalização positiva para LHR. Em conclusão, estes resultados sugeriram o envolvimento da regulação do LHCGR / LBPB com mecanismos relacionados ao desenvolvimento de folículos pré-antrais, especialmente durante o estabelecimento de folículos secundários. Além disso, os presentes dados reforçaram que a expressão reduzida de mRNA de LHR em ovários fetais bovinos no dia 150 estava relacionada à maior expressão de LRBP e bta-miR-222.

Sertraline is a selective serotonin reuptake inhibitor (SSRI) that is widely used for the treatment of depression and anxiety. Due to the abundant therapeutic use of sertraline, low levels have been detected in municipal wastewater effluents suggesting that aquatic organisms may be exposed. The purpose of this study was to evaluate the steroidogenic effects of sertraline on larval (FHM) and adult female fathead minnows (FFHM), Pimephales promelas. Larval FHM were exposed to 0.1, 1, and 10 µg/L sertraline for 28 days and analyzed via RT-qPCR for differential expression of 11β-Hydroxysteroid dehydrogenase (11β-HSD), 20β-Hydroxysteroid dehydrogenase (20β-HSD), aromatase (CYP19), and nuclear thyroid receptor alpha (TRα). FFHM were exposed to 3 or 10 µg/L sertraline for 7 days with the brain and ovary excised at exposure termination. Juvenile FHM exposed to 0.1 μg/L sertraline had a significant upregulation of both 20β-HSD and TRα. FFHM exposed to 10 µg/L sertraline had a significant upregulation of 11β-HSD expression in brain tissue, while no steroidogenic changes were observed in the FFHM ovary. Similarly, in FFHM brain tissue, CYP19 and 20β-HSD expression levels were significantly higher in fish exposed to 10µg/L sertraline compared to control. The significance of these findings with respect to survival, growth and reproduction are currently unknown, but represent future research needs.

Die vorliegende Arbeit untersucht die Steroidogenese und die Expression Leydig-Zellspezifischer Gene in Kulturen postnataler fetaler Leydig-Zellen (PFLC). Die Stimulation von PFLC mit hCG und (Bu)2cAMP bewirkt eine Steigerung der Testosteronproduktion in vitro. Es wurde eine zeitabhängige Abschwächung der Testosteronproduktion durch (Bu)2cAMPstimulierte PFLC beobachtet. Diese war begleitet von einer Akkumulation von Progesteron im Kulturmedium und einer Suppression der Expression von P450c17 auf dem translatorischen Level. Während der Kultivierung verloren PFLC ihre Fähigkeit der Expression Leydig-Zell-spezifischer Gene (z.B. 3βHSD, P450c17, Insl3). Dieses Phänomen konnte durch Stimulation mit (Bu)2cAMP rückgängig gemacht werden. Außerdem zeigte sich, dass PDGFα allein und in Kombination mit (Bu)2cAMP signifikant die Proliferation der PFLC in vitro stimulierte. Die vorliegende Arbeit deutet darauf hin, dass cAMP-aktivierte Signalkaskaden eine wichtige Rolle in der Regulation von Differenzierung und Funktion von PFLC spielen.

Steroid hormones in testis play an important role in spermatogenesis, maintenance of the male reproductive tract, production of semen and the maintenance of secondary sex characteristics and libido. They are also discussed as a target for substances called endocrine disruptors (EDs). No complex study was conducted on evaluation of relationships between EDs and steroid spectrum in 2 biological fluids; seminal plasma and plasma. The aim of the PhD. thesis was to develop and validate a method for determination of bisphenol A (BPA) and steroid spectrum in plasma and seminal plasma and to shed more light into mechanisms of ED action and effects of BPA and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis. Two new liquid-chromatography mass spectrometry methods for determination of BPA and 11 steroids in plasma and seminal plasma were developed and validated. The methods were used for estimation of analyte concentrations in 191 men with a different degree of fertility. Concurrently, the levels of six congeners of PCBs, gonadotropins, selenium and zinc in plasma were estimated. Partial correlations adjusted for age and BMI were calculated to evaluate relationships between these analytes. Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration...

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Endocrine disrupting compounds (EDCs) are exogenous compounds/chemicals in the environment that interfere with the synthesis, secretion, distribution and function or elimination of natural hormones in the body. Environmental estrogens are a subclass of EDCs that may mimic or inhibit the effect of endogenous estrogen and can therefore influence developmental and reproductive health in humans and animals. EDCs have been reported to adversely affect the reproductive, immune, endocrine and nervous systems of wildlife and humans. The effects of EDCs include gonadal abnormalities, altered male/female sex ratios, reduced fertility and cancers of the male and female reproductive tract to mention a few. These effects are difficult to detect. Although it is essential to screen for EDCs in aqueous environmental samples, most countries have failed to implement this as part of their routine water quality monitoring programs due to various constraints such as the high cost of assays and the lack of infrastructure and skills required to do the assays. Therefore, there is a clear need for more user-friendly, more economically viable and time saving assays that can be used for routine monitoring of environmental EDCs. The aim of this study was to investigate the comparison between chemical and tissue culture methods to monitor environmental estrogens. 28 environmental water samples were collected from various sites around South Africa and analyzed for EDCs using a battery of rapid in vitro tests. Samples collected for the current study were selected based on various human impacts and also to give approximately 50% high and 50% low estrogen values. The 28 environmental water samples were separated into two groups based on the estradiol ELISA. The estradiol ELISA was chosen because estradiol is the principal estrogen found in all mammalian species during their reproductive years. For this separation, an estradiol level of 5 pg/ml was used as cut-off. Of the 28 samples investigated, 15 had estradiol levels higher than 5 pg/ml and were designated as high estradiol. The remaining 13 samples contained estradiol at 5 pg/ml or less and they were designated as low estradiol The first objective of this study was to compare different rapid ELISAs for EDC monitoring to determine if the data obtained with these assays are similar/identical. The data obtained from the estrogenic ELISAs was related/similar and showed good correlation with each other. This is because the different estrogens are very similar and also due to the fact that the same sub-group in the population (the reproductively active females) is secreting these hormones. Therefore, an estradiol rapid assay was proposed as a first screening system for estrogens in samples. Even though there was a positive correlation between the estradiol rapid assay and testosterone rapid assay, separation of samples based on estradiol levels wasn’t a good predictor of testosterone levels in the samples. A testosterone rapid assay was therefore recommended as necessary to screen for androgens in samples. The positive correlation between the estradiol rapid assay and progesterone rapid assay was expected because both estradiol and progesterone are secreted and excreted by the same population sub-group (reproductively active females). This study also demonstrated a good predictability of separating samples containing progesterone using the estradiol ELISA. Progesterone is secreted by pregnant women, a sub-group of the reproductively active females. It is advised that a progesterone rapid assay be included to screen samples for progestogens The second objective of this study was to compare estradiol rapid ELISAs with a bioassay for anti-androgenicity using mouse testicular cell cultures. The mouse testicular cell testosterone synthesis bioassay to monitor anti-androgenicity of the samples showed no correlation between the ELISA data for estrogens. This study shows that anti-androgenic effects need to be monitored independently because the data for estrogenic compounds cannot be used as a predictor for anti-androgenic effects. This demonstrated the need for the inclusion of a mouse testicular cell testosterone synthesis bioassay to screen for androgenicity and anti-androgenicity of water samples. In summary, due to the different mechanisms of action of EDCs, this study recommended a battery of assays to monitor for EDCs. The battery of assays suggested is: v progesterone rapid assay was expected because both estradiol and progesterone are secreted and excreted by the same population sub-group (reproductively active females). This study also demonstrated a good predictability of separating samples containing progesterone using the estradiol ELISA. Progesterone is secreted by pregnant women, a sub-group of the reproductively active females. It is advised that a progesterone rapid assay be included to screen samples for progestogens. The second objective of this study was to compare estradiol rapid ELISAs with a bioassay for anti-androgenicity using mouse testicular cell cultures. The mouse testicular cell testosterone synthesis bioassay to monitor anti-androgenicity of the samples showed no correlation between the ELISA data for estrogens. This study shows that anti-androgenic effects need to be monitored independently because the data for estrogenic compounds cannot be used as a predictor for anti-androgenic effects. This demonstrated the need for the inclusion of a mouse testicular cell testosterone synthesis bioassay to screen for androgenicity and anti-androgenicity of water samples. In summary, due to the different mechanisms of action of EDCs, this study recommended a battery of assays to monitor for EDCs. The battery of assays suggested is: Estradiol ELISA as a rapid assay to screen for estrogens. Testosterone ELISA as a rapid assay to screen for androgens. Progesterone ELISA as a rapid assay to screen for progestogens. Mouse testicular cell testosterone synthesis bioassay to screen for androgenicity and anti-androgenicity.

Cortisol and dehydroepiandrosterone (DHEA) are steroids produced by the zona fasciculata (ZF) and reticularis (ZR), respectively, of the adrenal cortex. Both steroids are upregulated in response to adrenocorticotropic hormone (ACTH). Cortisol is a glucorticoid that is important in the regulation of inflammation and metabolism. DHEA is an adrenal androgen important in fetal growth and puberty but tends to decrease gradually after puberty in both men and women. DHEA has various effects on metabolism and immune function including inhibiting the effects of cortisol on some tissues. During the acute phase of stress, cortisol and DHEA rise due to an increase in ACTH released from the anterior pituitary. In contrast, during chronic stress, cortisol remains elevated but DHEA and ACTH levels decrease. Likewise, stress causes serum levels of IL-6 to increase. IL-6 increases cortisol release from the human and bovine adrenal cortex. IL-6 also decreases DHEA release from zona reticularis of the bovine adrenal gland. In humans the effect of IL-6 on DHEA production is still uncertain. To determine a possible mechanism of IL-6 on the zona fasciculata and reticularis, human H294R cells and bovine adrenal tissue were incubated in serum free medium containing IL-6, at various concentrations and incubation intervals. At the end of the incubation interval, mRNA or protein was extracted from the cells or tissue. Standard PCR, real time PCR, and western blot assays were used to determine the effects of IL-6 on the enzymes involved in cortisol and DHEA synthesis, steroidogenic factor-1 (SF-1), steroidogenic acute regulatory protein (StAR), and dosage sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX-1). In human H295R cells and bovine zona fasciculata cells IL-6 caused an increase in SF-1, StAR, P450scc, 17α hydroxylase, 3β-hydroxysteroid dehydrogenase type 2 (3β HSD2), 21 hydroxylase, and 11β hydroxylase mRNA and protein. IL-6 caused DAX-1 mRNA and protein to decrease. These effects were manifest in a time dependent manner. Dose response treatments incubated for 60 min increased SF-1, StAR, P450scc, 17α hydroxylase, 3β HSD2, 21 hydroxylase, and 11β hydroxylase but there was not significant change between the different treatments of IL-6. The bovine zona reticularis stimulated with IL-6 showed a decrease in SF-1, StAR, P450scc, 17α hydroxylase, and 3β HSD2 with an increase in DAX-1 mRNA and protein. This response was manifest in a time dependent manner for both mRNA and protein, and the effect was dose-dependent for mRNA but not protein levels within the 60 min time period. These data provide a mechanism by which increased stress, physical or emotional, which increases IL-6 serum level, could increase cortisol and decrease DHEA. This would account for decreased immune function, increased blood pressure, and changes in metabolism.

Pendant la grossesse, les hormones stéroïdes jouent un rôle indispensable dans la régulation des principales manifestations physiologiques telles que la reconnaissance maternelle de la gestation, la réceptivité de l'endomètre, le début du développement embryonnaire ainsi que le maintien de la gestation. Cependant, on sait très peu sur la production de ces hormones et les principaux facteurs des voies intracellulaires impliqués dans le processus de stéroïdogenèse dans le placenta bovin pendant les stades initiaux et plus avancés de la gestation. Par ailleurs, certaines anomalies du placenta chez les bovins suite à une mauvaise production de stéroïdes n'ont pas encore été démontrées. Les objectifs de cette thèse étaient donc de : 1) déterminer la présence et la localisation des principales protéines stéroïdiennes dans le placenta de bovins provenant de gestations de 50 à 120 jours, 2) comparer l'expression placentaire d'une série de gènes et de protéines stéroïdiennes entre une gestation impliquant un transfert de noyaux de cellules somatiques (SCNT) et une gestation non-clonale; 3) étudier l'impact des hormones trophiques et des seconds messagers sur la stéroïdogenèse dans le placenta bovin à 140 +10 jours de gestation. L’utilisation de techniques d’immunohistochimie, d’immunobuvardage et de PCR quantitatif nous a permis d’évaluer la présence d'un large éventail de gènes stéroïdiens (STAR, CYP11A1, HSD3B1, CYP17A1 et SCARB1) qui participent au transport du cholestérol et dans la production de différents types de stéroïdes. Dans cette thèse, nous avons démontré la capacité du placenta bovin d’initier la stéroïdogenèse au début de la gestation et nous avons également déterminé les principales cellules impliquées dans ce processus. Nous avons constaté que les tissus maternels expriment les principaux marqueurs de stéroïdogenèse suggérant une plus grande capacité stéroïdogénique que les tissus fœtaux. En outre, un modèle d'expression des protéines complémentaires stéroïdogéniques entre la caroncule et le cotylédon a été observé, indiquant que la stéroïdogenèse placentaire exige une communication cellule à cellule entre les cellules de la mère et du fœtus. Après avoir démontré les principales cellules impliquées dans la synthèse des hormones stéroïdiennes dans le placenta bovin en début de gestation, nous avons ensuite étudié les modifications possibles de la stéroïdogenèse dans les tissus SCNT cotylédonaires à 40 jours de gestation. Nous avons identifié d'importantes modifications dans l'expression des gènes STAR, CYP11A1, HSD3B1, CYP17A1, et SULT1E1. Conséquemment, nous postulons que l'expression réduite des gènes stéroïdiens peut provoquer une insuffisance de la biosynthèse des hormones stéroïdiennes, ce qui pourrait contribuer à un développement anormal du placenta et du fœtus dans les gestations SCNT à court ou long terme. Finalement, nous avons développé un modèle efficace de culture d’explants de placentome qui nous a permis d'explorer les mécanismes sous-jacents spécifiques à la stéroïdogenèse placentaire. Nous avons exploré l'effet stimulant des hormones trophiques et différents messagers secondaires sur l'expression de différentes protéines stéroïdogéniques ainsi que le taux de progestérone (P4) dans les explants de placentome. En utilisant les techniques de RIA et de PCR quantitatif, nous avons constaté que même si les analogues de l'hormone lutéinisante (hCG) ont un effet stimulant sur plusieurs gènes stéroïdiens, le calcium ionophore est le principal modulateur dans la synthèse de la P4. Ces résultats suggèrent que dans le placenta bovin, la synthèse de la P4 est modulée principalement par l'afflux de calcium intracellulaire, et apparemment les nucléotides cycliques ne semblent pas contrôler ce processus. En conclusion, cette étude contribue de manière significative à une meilleure compréhension des mécanismes d'entraînement de la synthèse des stéroïdes placentaires au début de la gestation et permet aussi d’apporter de nouveaux éclairages sur l'importance des stéroïdes placentaires dans la régulation du développement du placenta et du fœtus. / During pregnancy, steroid hormones have essential roles in regulating key physiological events such as maternal recognition, endometrial receptivity, early embryonic development, and maintenance of pregnancy. However, very little is known about the production of these hormones nor about the principal factors and intracellular pathways implicated in the steroidogenic process in bovine placenta, during early and advanced pregnancy. In addition, placental abnormalities in cattle following an improper steroid production in bovine placenta have not been yet demonstrated. The aims of this thesis were to: 1) determine the occurrence and localization of the principal steroidogenic proteins in bovine placenta from day 50 to day 120 of pregnancy; 2) compare the placental expression of a series of steroidogenic genes and proteins between somatic cell nuclear transfer (SCNT) pregnancies and non-SCNT gestations; 3) investigate the impact of trophic hormone, and second messengers on steroidogenesis in bovine placenta at 140 +10 days of gestation. Using immunohistochemistry, western blot and qPCR techniques, we evaluated the presence of a wide range of steroidogenic genes (STAR, CYP11A1, HSD3B1, CYP17A1 and SCARB1), that participate in the cholesterol transport and in the production of different types of steroids. In this thesis, we demonstrated the capability of the early bovine placenta to initiate steroidogenesis, and we also determined the principal cells implicated in this process. We found that maternal tissue expresses the principal steroidogenic markers suggesting it has a greater steroidogenic capacity compared to fetal tissue. Moreover, a complementary pattern of steroidogenic protein expression between the caruncle and the cotyledon were found, indicating that placental steroidogenesis requires cell to cell communication between the maternal and fetal cells. Having shown the principal cells involved in the synthesis of steroid hormones in bovine placenta during early pregnancies, we then studied possible alterations in steroidogenesis in cotyledonary tissue in SCNT at 40 days of pregnancy. We identified significant alterations in the expression of STAR, CYP11A1, HSD3B1, CYP17A1 and SULT1E1 transcripts. Therefore, we postulate that reduced expression of steroidogenic genes may cause an insufficient local biosynthesis of steroid hormones, which might contribute to the abnormal placental and fetal development in SCNT gestations at short or long term. Finally, we developed an efficient placentome explants culture model that allowed us to explore the specific mechanisms underlying placental steroidogenesis. We explored the stimulatory effect of trophic hormones and different second messengers on the expression of various steroidogenic proteins and the progesterone levels in placentome explants. By RIA and qPCR techniques, we found that although LH-like hormones (hCG), had a stimulatory effect on multiple steroidogenic genes, the calcium ionophore was the principal modulator in the synthesis of progesterone. These results suggest that in bovine placenta, the synthesis of progesterone is modulated principally by intracellular calcium influx, and cyclic nucleotides do not seem to be controlling this process. In conclusion, these studies significantly contribute to a better understanding of the driving mechanisms of placental steroid synthesis in early gestations and also provide new insights into the importance of placental steroids in the regulation of placental and fetal development.