RESUMO
In Bufo arenarum, the biosynthesis of testosterone and 5alpha-dihydrotestosterone takes place through a complete 5-ene pathway, 5-androsten-3beta,17beta-diol being the immediate precursor of testosterone. Besides androgens, testes are able to synthesise 5alpha-pregnan-3,20-dione and several 3alpha and 20alpha reduced derivatives. During the breeding season, steroid biosynthesis turns from androgen to C21-steroid production. As a consequence, the cytochrome P450 17-hydroxylase, C17,20-lyase (CypP450(c17)) could be a key enzyme in that metabolic shift. The present study demonstrates that in testes of B. arenarum, CypP450(c17) co-localises with glucose-6-phosphatase in the microsomal fraction. CypP450(c17) possesses more affinity for pregnenolone than for progesterone in both non-reproductive (Km = 43.76 +/- 4.63 nM and 2,170 +/- 630 nM, respectively) and reproductive (Km = 37.46 +/- 4.19 nM and 3,060 +/- 190 nM, respectively) seasons. These results could explain the predominance of the 5-ene pathway for testosterone biosynthesis. Toad CypP450(c17) activity is higher in the non-reproductive period than the reproductive period, suggesting that this enzyme is an important factor in toad steroidogenic changes. Animals in reproductive conditions showed a significant reduction in circulating androgens. This is in agreement with the decrease in Vmax of cytochrome P450 17-hydroxylase activity, enhancing the physiological relevance of these in vitro results.
Assuntos
Bufo arenarum/metabolismo , Estações do Ano , Esteroide 17-alfa-Hidroxilase/metabolismo , Testículo/metabolismo , Animais , Soros Imunes , Cinética , Masculino , Frações Subcelulares/metabolismo , Testosterona/sangue , Distribuição TecidualRESUMO
Se presenta un caso de linfoma con localización en la glándula testicular, al cual se le realizó orquiectomía y tratamiento quimioterápico. Se comentan algunas particularidades con respecto a la patología y clínica de esta afección
Assuntos
Pessoa de Meia-Idade , Humanos , Masculino , Linfoma não Hodgkin/patologia , Neoplasias Testiculares/patologiaRESUMO
Se presenta un caso de linfoma con localización en la glándula testicular, al cual se le realizó orquiectomía y tratamiento quimioterápico. Se comentan algunas particularidades con respecto a la patología y clínica de esta afección (AU)