FOLLICLE-STIMULATING-HORMONE RECEPTOR-MEDIATED UPTAKE OF CA-45(2+) BY CULTURED RAT SERTOLI CELLS DOES NOT REQUIRE ACTIVATION OF CHOLERA TOXIN-SENSITIVE OR PERTUSSIS TOXIN-SENSITIVE GUANINE-NUCLEOTIDE BINDING-PROTEINS OR ADENYLATE-CYCLASE

We have previously reported that FSH stimulates flux of45Ca2+into cultured Sertoli cells from immature rats via voltage-sensitive and voltage-independent calcium channels. In the present study, we show that this effect of FSH does not require cholera toxin (CT)- or pertussis toxin (PT)-sensitive guanine nucleotide binding (G) protein or activation of adenylate cyclase (AC). Significant stimulation of45Ca2+influx was observed within 1 min, and maximal response (3.2-fold over basal levels) was achieved within 2 min after exposure to FSH. FSHstimulated elevations in cellular cAMP paralleled increases in45Ca2+uptake, suggesting a possible coupling of AC activation to45Ca2+influx. (Bu)2cAMP, however, was not able to enhance45Ca2+uptake over basal levels at a final concentration of 1000 µM, although a concentration-related increase in androstenedione conversion to estradiol was evident. Exposure of Sertoli cells to CT (10 ng/ml) consistently stimulated basal levels of androstenedione conversion to estradiol but had no effect on basal levels of45Ca2+uptake. Similarly, CT had no effect on FSHinduced45Ca2+uptake, but potentiated FSH-stimulated estradiol synthesis. PT (10 ng/ml) augmented basal and FSH-stimulated estradiol secretion without affecting45Ca2+influx. The adenosine analog N6-phenylisopropyladenosine, which binds to Gi-coupled adenosine receptors on Sertoli cells, inhibited FSH-stimulated androgen conversion to estradiol in a dose-related (1-1000 nM) manner, but FSH-stimulated45Ca2+influx remained unchanged. Our results show that in contrast to FSH-stimulated estradiol synthesis, the flux of45Ca2+into Sertoli cells in response to FSH is not mediated either directly or indirectly by CT- or PTsensitive G protein, nor does it require activation of AC. Our data further suggest that the FSH receptor itself may function as a calcium channel. © 1990 by The Endocrine Society.