Comparison of the effects of insulin and follitropin on @entity413 metabolism by Sertoli cells from immature XXXX .

@entity268 @entity43554 @entity1880 @entity880 @entity8279 @entity35 @entity413
Sertoli cells were isolated from the testes of 3-week-old sterile @entity35 (prenatally irradiated) and incubated for 3 days in the absence of added hormones. Subsequently the effects of follitropin and insulin on @entity413 metabolism were investigated using this in vitro system. A marked stimulation of net @entity880 production by either follitropin or insulin was observed within 3 h after addition of the hormones. This response was not inhibited in the presence of the protein synthesis inhibitor @entity1880 . Production of @entity268 by the Sertoli cells was markedly enhanced by @entity43554 , but not at all by insulin. The addition of 0.5 mM @entity8279 to the incubation medium also resulted in a rapid increase of the rate of @entity880 production by the Sertoli cells. The stimulation of @entity880 production by follitropin and insulin was dose-dependent (ED50 of approx. 10 ng NIH-FSH-S13/ml and of approx. 50 ng insulin/ml). It is suggested that the observed effects of insulin on Sertoli cells are mediated via insulin receptors, rather than via receptors for insulin-like growth factors. Within 18 h after addition of either follitropin or insulin the cells became refractory with respect to @entity880 production to the homologous hormone, whereas the cells could still respond to the heterologous hormone. It is concluded, that follitropin and insulin, acting via different mechanisms, exert similar rapid stimulatory effects on @entity413 metabolism by Sertoli cells from immature @entity35 in vitro. These effects are not dependent on de novo protein synthesis and may differ from long-term trophic effects of follitropin, insulin, and/or insulin-like growth factors.
