Efeitos da leptina no inicio da puberdade em animais machos
DOI:
https://doi.org/10.17533/udea.rccp.324260Palavras-chave:
esteroidogénese em bovinos, hormônio gonadotrófico, produção de estrógenos, produção de testosterona, receptor de gonadotrofinasResumo
A leptina é um hormônio de 16 KDa produzida principalmente pelo tecido adiposo, codificada pelo gene ob e composta por 146 aminoácidos. Cumpre suas funções na periferia do organismo no eixo hipotálamo – hipófise – gônadas. Em varias espécies tem-se estudado o efeito deste hormônio na reprodução; as mudanças na concentração e em sua expressão poderiam estar associadas com o inicio da puberdade em diferentes espécies animais e em humanos. O papel da leptina na reprodução em machos tem sido estudado especialmente em ratas e ratos, porém também tem sido realizadas pesquisas em humanos e outras espécies animais. Nas células de Leydig, nos túbulos seminíferos, as espermatogônias e os espermatozóides, entre outros tipos de células, existe expressão dos receptores e o RNAm de receptores de leptina, o que indica que pode existir uma função importante da leptina nos testículos. Em geral, tem sido encontrado um efeito inibitório da testosterona com a secreção da leptina e vice versa, o qual indica que a leptina pode regular a esteroidogénese no testículo. A leptina também pode atuar nas células não diferenciadas do testículo para permitir sua diferenciação em espermatócitos e pode ajudar à célula a través de toda sua diferenciação e maturação até espermátides. A análise de todos estes resultados obtidos, permite considerar a leptina como um importante hormônio que pode estar envolvido em funções vitais do eixo neuroendócrino e reprodutivo do macho.
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