Dehydroepiandrosterone (DHEA) modulates GHRH, somatostatin and angiotensin II action at the pituitary level

Abstract

In view of the present controversy related to the potential beneficial effects of clinical dehydroepiandrosterone (DHEA) treatments, and considering our own previous results that reveal an influence of this steroid in pituitary hyperplasia development in vivo in rats, we decided to evaluate the role of DHEA in prolactin and GH secretion, as well as in second messengers involved, in cultured rat anterior pituitary cells. DHEA (1 × 10−5 to 1 × 10−7 M) did not modify basal GH or prolactin release, and a prolactin inhibitory effect was observed only for androstenediol, a metabolite of DHEA. DHEA partially prevented dopamine (1 × 10−6 M)-induced prolactin inhibition and facilitated the prolactin-releasing effect of 10−8 M Ang II, without modifying the resulting Ca2+i mobilization. Furthermore, DHEA potentiated the GH release and cAMP production induced by 1 × 10−8 M GHRH. Finally, DHEA partially reversed the inhibitory effect of 1 × 10−8 M somatostatin on GH, but not prolactin, release. We conclude that DHEA in vitro, directly or indirectly through conversion into metabolites, is able to modulate the hormonal response of the pituitary to hypothalamic regulators. It can enhance pituitary prolactin release and induce GH secretion. These effects could help explain some of the side effects observed in prolonged DHEA treatments in vivo and should be taken into account when considering its use in human clinical trials.