RESUMEN
The intratesticular testosterone concentration is high during the early postnatal period although the intracellular androgen receptor expression (iAR) is still absent in Sertoli cells (SCs). This study aimed to evaluate the non-classical effects of testosterone and epitestosterone on calcium uptake and the electrophysiological effects of testosterone (1µM) on SCs from rats on postnatal day (pnd) 3 and 4 with lack of expression of the iAR. In addition, crosstalk on the electrophysiological effects of testosterone and epitestosterone with follicle stimulating hormone (FSH) in SCs from 15-day-old rats was evaluated. The isotope (45)Ca(2+) was utilized to evaluate the effects of testosterone and epitestosterone in calcium uptake. The membrane potential of SCs was recorded using a standard single microelectrode technique. No immunoreaction concerning the iAR was observed in SCs on pnd 3 and 4. At this age, both testosterone and epitestosterone increased the (45)Ca(2+) uptake. Testosterone promoted membrane potential depolarization of SCs on pnd 4. FSH application followed by testosterone and epitestosterone reduced the depolarization of the two hormones. Application of epitestosterone 5 min after FSH resulted in a delay of epitestosterone-promoted depolarization. The cell resistance was also reduced. Thus, in SCs from neonatal Wistar rats, both testosterone and epitestosterone act through a non-classical mechanism stimulating calcium uptake in whole testes, and testosterone produces a depolarizing effect on SC membranes. Testosterone and epitestosterone stimulates non-classical actions via a membrane mechanism, which is independent of iAR. FSH and testosterone/epitestosterone affect each other's electrophysiological responses suggesting crosstalk between the intracellular signaling pathways.
Asunto(s)
Andrógenos/farmacología , Epitestosterona/farmacología , Células de Sertoli/fisiología , Animales , Animales Recién Nacidos , Calcio/metabolismo , Hormona Folículo Estimulante/farmacología , Hormona Folículo Estimulante/fisiología , Masculino , Potenciales de la Membrana , Ratas Wistar , Células de Sertoli/efectos de los fármacos , Testículo/citología , Testículo/efectos de los fármacosRESUMEN
Epitestosterone is the 17α-epimer of testosterone. This steroid possesses antiandrogenic activities. The mechanism of action of epitestosterone has not been elucidated. The aim of this study was to investigate the nonclassical effect of epitestosterone on the membrane of Sertoli cells in proliferative phase (rats aged 15 days) and in nonproliferative phase (rats aged 21 and 35 days). The membrane potential of Sertoli cells was recorded using a standard single microelectrode technique. Epitestosterone (0.5, 1, and 2 µM) or testosterone (1 µM) was administered alone and after infusion with flutamide (1 µM), verapamil (100 µM), or U-73122 (2 µM). The testes of rats aged 12-15 days were preincubated with 45Ca2+ with or without flutamide (1 µM) and incubated with epitestosterone (1 µM) or testosterone (1 µM). Epitestosterone and testosterone produced a depolarization in the membrane potential and increased the membrane input resistance on Sertoli cells from rats of all 3 ages. The effect of epitestosterone did not change after perfusion with flutamide. Epitestosterone increased 45Ca2+ uptake within 5 min and this effect was not inhibited by flutamide. The absence of an effect by flutamide suggests that epitestosterone acts independently of the intracellular androgen receptor. The depolarizing effect was inhibited by verapamil, a voltage-dependent calcium channel blocker, and by U-73122, a phospholipase C inhibitor. These results indicate that epitestosterone acts on the membrane via a nonclassical signaling pathway; the effect was similar to the testosterone action on membrane of Sertoli cells in whole seminiferous tubules from rat testes.
Asunto(s)
Membrana Celular/fisiología , Epitestosterona/farmacología , Túbulos Seminíferos/citología , Células de Sertoli/citología , Células de Sertoli/fisiología , Testosterona/farmacología , Animales , Calcio/metabolismo , Canales de Calcio/metabolismo , Canales de Calcio Tipo L/metabolismo , Membrana Celular/efectos de los fármacos , Flutamida/farmacología , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Masculino , Potenciales de la Membrana/efectos de los fármacos , Ratas , Ratas Wistar , Receptores Androgénicos/metabolismo , Células de Sertoli/efectos de los fármacos , Fosfolipasas de Tipo C/metabolismoRESUMEN
Progesterone, epitestosterone (4-androstene-17 alpha-ol-3-one, EpiT) and 4- androstene-3-one-17 beta-carboxylic acid (COOH), three known in vitro inhibitors of 5 alpha reductase, were injected daily for 30 days to male rats to study their effect on some parameters of epididymal function. Progesterone at the dose of 750 and 2000 micrograms/day decreased fertility by 59% and 50% respectively. EpiT at a dose of 1500 micrograms/day decreased fertility by 74%. These treatments did not change the sperm counts in the cauda epididymis. Treatment with COOH did not decrease fertility. Progesterone at 750 and 2000 micrograms/day and EpiT at 750 micrograms/day decreased the weight of the epididymis, prostate and seminal vesicles. None of the compounds tested produced variations in body weight or in the weight of liver and testis. The 5 alpha reductase activity of epididymis, testis and liver was diminished by progesterone treatment, while EpiT decreased only that of testis and liver.