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Raphael Escorsim Szawkahttp://lattes.cnpq.br/0510186251387892http://lattes.cnpq.br/6405171758896382Patricia Costa Henriques2021-04-14T00:03:28Z2021-04-14T00:03:28Z2017-12-01http://hdl.handle.net/1843/35678O pico na secreção de hormônio luteinizante (LH) é um evento chave para a ovulação e fertilidade em fêmeas. A liberação do LH está sob o controle do estradiol (E2) através de mecanismos de retroalimentação negativa e positiva que parecem envolver, respectivamente, o núcleo anteroventral periventricular (AVPV) da área pré-óptica (POA) e no núcleo arqueado do hipotálamo (ARC). Neste trabalho, investigamos se AVPV e ARC responderiam de forma diferenciada a níveis de E2 que exercem efeitos de retroalimentação negativa ou positiva. Para isto, foram utilizadas ratas ciclando em diestro (DI) ou proestro (PRO) e ratas ovariectomizadas (OVX) tratadas com óleo ou diferentes doses de E2 (OVX+E2). No experimento 1, foram feitas coletas seriadas de sangue das 13:00 h às 18:00 h, para análise dos níveis de E2, LH e prolactina (PRL). Após a última coleta, as ratas foram perfundidas e os cérebros processados para análise imunohistoquímica. No experimento 2, as ratas foram decapitadas e POA e ARC foram dissecados para análise do RNAm de Kiss1, Esr1 e Esr2. Os níveis plasmáticos de E2 se encontraram aumentados no PRO. Os tratamentos com E2 aumentaram o E2 plasmático, sendo os níveis encontrados em ratas tratadas com dose de 20 μg/rata/dia de E2 (OVX+E220) semelhantes aos do PRO. Ratas em PRO exibiram o pico preovulatório de LH, o qual foi replicado em ratas OVX+E220. Por outro lado, ratas tratadas com 1 μg/rata/dia de E2 (OVX+E21) apresentaram redução dos níveis de LH em relação a ratas OVX. Todas as doses de E2 utilizadas foram capazes de promover um pico de secreção de PRL, semelhante ao pico do PRO. Consistente com a ocorrência do pico de LH, a expressão de receptor para progesterona (PR) e c-Fos no AVPV aumentou apenas nas ratas em PRO e OVX+E220. No ARC, em contrapartida, ambas as doses de E2 nas ratas OVX+E21 e OVX+E220 induziram aumento da marcação de PR, aumento da expressão de PR em neurônios kisspeptina e redução do número de neurônios kisspeptina- imunorreativos (ir), à semelhança de ratas em DI e PRO. A porcentagem de neurônios-ir à receptor para estrógeno do tipo alfa (ERα) foi aumentada no AVPV de ratas OVX+E220. O RT-PCR revelou um efeito dose-resposta do E2 sobre o RNAm de Kiss1, com aumento na POA e diminuição no ARC. Ainda, o ARC apresentou maior expressão de Esr1 em comparação ao AVPV em ratas OVX+E21 e maior razão Esr1/Esr2, independente do nível de E2. Os resultados demonstram que neurônios do ARC e AVPV respondem a baixos e altos níveis de E2, respectivamente. Baixos níveis de E2 inibem, enquanto altos níveis estimulam a secreção de LH. Assim, a diferença de sensibilidade ao E2 no ARC e AVPV parece exercer um importante papel na gênese dos efeitos de retroalimentação negativa e positiva sobre a secreção de LH.The preovulatory surge of luteinizing hormone (LH) is a key event responsible for ovulation and fertility in females. LH secretion is under estradiol (E2) control, through negative and positive feedback mechanisms that seem to evolve, respectively, the anteroventral periventricular nucleus (AVPV) of the preoptic area (POA) and the arcuate nucleus of the hypothalamus (ARC). Here, we investigated whether the AVPV and the ARC would respond differently to negative and positive feedback levels of E2. We used cycling rats on diestrus (DI) or proestrus (PRO) and ovariectomized (OVX) rats treated with oil or E2 (OVX+E2) in different doses. In experiment 1, serial blood collection was performed from 13:00 h to 18:00 h, in order to analyze E2, LH and prolactin (PRL) levels. After the last blood sampling, rats were perfused and the brains were processed for immunohistochemistry. In experiment 2, rats were decapitated and the POA and ARC were dissected for Kiss1, Esr1 and Esr2 mRNA analysis. Plasma E2 levels were elevated in PRO. E2 treatments increased plasma E2 levels, with rats treated with 20 μg/rat/day (OVX+E220) displaying similar values to PRO. Rats on PRO exhibited the preovulatory LH surge, which was replicated in OVX+E220 rats. On the other hand, rats treated with 1 μg/rat/day E2 (OVX+E21) showed only a decrease in LH levels compared to OVX rats. All E2 doses were able to promote surges of PRL secretion, likewise PRO. Consistent with the occurrence of the LH surge, expression of progesterone receptor (PR) and c-Fos in the AVPV increased only in PRO and OVX+E220 rats. However, in the ARC, both low and high levels of E2 in OVX+E21 and OVX+E220 rats, respectively, increased PR single labeling, PR coexpression in kisspeptin neurons and decreased the number of kisspeptin-immunoreactive (ir) neurons, to the levels found in DI and PRO rats. The percentage of estrogen receptor alpha (ERα)-ir neurons increased in the AVPV of OVX+E220 rats. RT-PCR revealed 9 dose-response effects of E2 on Kiss1 mRNA levels, with stimulation in the POA and inhibition in the ARC. Moreover, the ARC showed higher Esr1 expression compared to the AVPV in OVX+E21 rats, and a higher Esr1/Esr2 ratio regardless of the E2 levels. The results demonstrate that neurons in the ARC and AVPV respond selectively to low and high levels E2, respectively. Low E2 inhibits, while high E2 stimulates LH secretion. Thus, the differential sensitivity of ARC and AVPV neurons to E2 seems to play a role in the switch between negative- and positive-feedback effects on LH secretion.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas GeraisporUniversidade Federal de Minas GeraisPrograma de Pós-Graduação em Ciências Biológicas - Fisiologia e FarmacologiaUFMGBrasilICB - INSTITUTO DE CIÊNCIAS BIOLOGICAShttp://creativecommons.org/licenses/by-nc-nd/3.0/pt/info:eu-repo/semantics/openAccessFisiologiaEstradiolHormônio luteinizanteNúcleo arqueado do hipotálamoProlactinaEstradiolHormônio luteinizanteNúcleo anteroventral periventricularNúcleo arqueadokisspeptinaProlactinaSensibilidade diferenciada dos núcleos anteroventral periventricular e arqueado ao estradiol como parte dos mecanismos de retroalimentação positiva e negativa sobre o eixo gonadalinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisreponame:Repositório Institucional da UFMGinstname:Universidade Federal de Minas Gerais (UFMG)instacron:UFMGORIGINALTRABALHO A SER DIVULGADO.pdfTRABALHO A SER DIVULGADO.pdfapplication/pdf895824https://repositorio.ufmg.br/bitstream/1843/35678/1/TRABALHO%20A%20SER%20DIVULGADO.pdfedb0b2270455184924b3d872d46f2f0cMD51CC-LICENSElicense_rdflicense_rdfapplication/rdf+xml; charset=utf-8811https://repositorio.ufmg.br/bitstream/1843/35678/2/license_rdfcfd6801dba008cb6adbd9838b81582abMD52LICENSElicense.txtlicense.txttext/plain; charset=utf-82119https://repositorio.ufmg.br/bitstream/1843/35678/3/license.txt34badce4be7e31e3adb4575ae96af679MD531843/356782021-04-13 21:03:28.501oai:repositorio.ufmg.br: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Repositório InstitucionalPUBhttps://repositorio.ufmg.br/oaiopendoar:2021-04-14T00:03:28Repositório Institucional da UFMG - Universidade Federal de Minas Gerais (UFMG)false
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