Effects of FSH, Insulin and IGF-I on rat Sertoli cells

The response of Sertoli cells in vivo to FSH may be complex, as indicated by the important role played by FSH in the initiation and recovery of spermatogenesis (section 1.1). A large number of processes in Sertoli cells in culture can be stimulated by FSH. Some of these processes are typical for Sertoli cells, for example the secretion of androgen binding protein and a high aromatase activity, which converts testosterone to estradiol, but other processes involve general metabolism. The functional importance of androgen binding protein and aromatase activity with respect to spermatogenesis has not yet been elucidated. We have chosen to study glucose metabolism as a parameter in the present experiments for a number of reasons. As mentioned above, glucose metabolism is important for the supply of energy substrates to spermatogenic cells (section 1.1), and is relatively easy to measure in vitro. Insulin is known as one of the main regulatory hormones for glucose metabolism, and insulin-like growth factor I (IGF-I) can perform insulin-like actions. Hence, we have investigated insulin and IGF-I effects on glucose metabolism by Sertoli cells as compared with the effects of FSH