Androgens rapidly increase the cytosolic calcium concentration in Sertoli cells

Abstract

We demonstrate that androgens rapidly and specifically increase intracellular calcium in Sertoli cells, investigate the mechanism, and suggest the unifying hypothesis that calcium might be a common intracellular molecular effector to explain the known synergism between FSH and testosterone (T) action on Sertoli cells in support of spermatogenesis. In freshly isolated Sertoli cells, T and its 5 alpha-reduced metabolite dihydrotestosterone increased intracellular calcium from 83 +/- 4 to 147 +/- 8 and 167 +/- 29 nM, respectively, whereas estradiol had minor (117 +/- 9 nM) and progesterone no (80 +/- 6 nM) effect. The effect of T was rapid (20-40 sec) and inhibited by 1) preincubation with either a pure nonsteroidal antiandrogen (hydroxyflutamide) or a 5 alpha-reductase inhibitor (finasteride) or 2) removal of extracellular calcium (47 +/- 4 nM) or pharmacological blockade of voltage-activated (62 +/- 5 nM) or voltage-independent (55 +/- 14 nM) membrane calcium channels. These findings suggest that the T-induced rise in Sertoli cell cytosolic calcium involves sequential 5 alpha-reduction, binding to a classical androgen receptor, and activation of transmembrane influx of extracellular calcium. Immobilization of T by conjugation to a large carrier molecule (BSA) to prevent steroid entry into Sertoli cells also resulted in a rapid increase in cytosolic calcium to a similar magnitude as unconjugated T, consistent with a plasma membrane site of action. This finding together with the rapid cytosolic calcium rise caused by T argues for the possible existence of a short term, nongenomic effects in hormonal regulation of Sertoli cell function in addition to the well known, slower genomic response.