Basal and HCG-stimulated testosterone production by interstitial cells of the Mongolian gerbil (Meriones unguiculatus)--II. Influence of glucocorticosteroids and steroidal precursors.

Compared to testosterone production by Mongolian gerbil interstitial cells in the absence of HCG or precursors, testosterone formation was significantly elevated by the addition of 100 ng pregnenolone, progesterone, 17-hydroxyprogesterone or DHEA. Production increased linearly with the amounts of precursors added (pregnenolone: r = 0.99; progesterone: r = 0.98; 17-OH-progesterone: r = 0.96; DHEA: r = 0.92, N = 40, all P less than 0.001). Approximately 50% of DHEA were converted to testosterone during the 6-hr incubation period. Neither the addition of 100 ng 11-deoxycortisol, 11-deoxycorticosterone, cortisol, corticosterone, cortisone, 18-OH-corticosterone, 21-deoxycortisone or 11-dehydrocorticosterone, nor of 100 ng estradiol had a significant effect on testosterone production by isolated interstitial cells incubated without or with 1 mIU HCG. Testosterone production by isolated interstitial cells was significantly increased within 2 min after the addition of 100 ng DHEA; production then linearly increased with the length of incubation (r = 0.98, N = 40, P less than 0.001). After addition of as little as 2 ng DHEA, testosterone formation was higher than by cells incubated without DHEA. While testosterone production could not be stimulated by the addition of 1-500 microIU HCG during a 30-min incubation period, it was drastically elevated by the addition of 10, 20 or 100 ng DHEA. Steroidal precursor concentrations secreted by the Mongolian gerbil adrenal gland incubated in vitro for 120 min were too low to stimulate testosterone production by interstitial cells. On the other hand, testosterone synthesis could be increased by the addition of 10-100-microliter aliquots of adrenal extracts.