Abstract: Leydig cells were isolated and purified by a discontinuous Percoll gradient (5%,30%,58%,70%).Purified cells were dispensed into 24-well plate and maintained for 24h in a CO2 incubator.Leydig cells were treated with taurine independently or coadministered with human chorionic gonadotropin(HCG),androstenedione,progesterone and cyclic adenosine monophosphate(cAMP).Testosterone levels were measured by radioimmunoassay. The results showed that taurine can affect testosterone secretion significantly in a biphasic pattern. Taurine at the concentration (0.1～100 μg/mL) increased testosterone secretion ,whereas the higher dose (400 μg/mL)inhibited testosterone secretion. Taurine can stimulate the convertion from androstenedione and progesterone to testosterone,which can also stimulate the testosterone secretion induced by HCG and cAMP．It is concluded that taurine can stimulate testosterone secretion ,which affect several aspects of testosterone biosynthesis.

Key words: taurine, leydig cells, testosterone, rat