Regulation of FSH receptor, PKIbeta, IL-6 and calcium mobilization: Possible mediators of differential action of FSH.

Sertoli cells support the development of germ cells by providing a microenvironment in the seminiferous tubules. FSH stimulates Sertoli cell proliferation only during neonatal period till day 18 in the immature rat whereas FSH regulates only functional parameters in the adult rat Sertoli cells. This suggests that FSH exerts differential action in immature and adult Sertoli cells. In an attempt to elucidate the mechanism by which FSH exerts the differential effects, we have carried out both in vivo and in vitro studies using Sertoli cells isolated from immature (7-10 days old) and adult (90 days old) rats. The differential role of FSH was studied at the receptor as well as at the signaling level. Monitoring the level of expression of FSH receptor by RTPCR and northern blot analysis revealed that the expression was more in immature Sertoli cells. Furthermore, it was found that FSH up (1.8-fold) regulates its receptor level only in the immature Sertoli cells and not in the adult. Results also revealed that PKIbeta and calcium, which are the downstream signaling molecules, are involved in FSH regulated Sertoli cells proliferation. It was also observed that FSH up (1.4-fold) regulates the levels of expression of IL-6 mRNA only in the immature rat Sertoli cells suggesting the possibility of its involvement in FSH regulated Sertoli cell proliferation.