GROWTH-RESPONSE OF ADULT GERM-CELLS TO RAT ANDROGEN-BINDING PROTEIN AND HUMAN SEX HORMONE-BINDING GLOBULIN

Androgen-binding protein (ABP) is produced by Sertoli cells depending on the development and the stage of the spermatogenic cycle. Germ cell proliferation is at its peak when ABP is at its peak and secreted tow ards the testicular basal compartment containing spermatogonia and pre meiotic spermatocytes. Rat isolated adult germ cell DNA synthesis was studied in vitro in the presence of ABP with and without steroids and in the presence of pure or recombinant sex steroid hormone-binding glo bulin (SHBG) using thymidine incorporation. Results are: SHBG is able to promote DNA synthesis in the absence of cofactors. Testosterone rea cted negatively to the stimulatory effect of SHBG. We conclude that AB P, the physiological steroid-binding protein, should be considered as a paracrine regulator of spermatogenic DNA synthesis in the adult rat.