Effects of evodiamine on the secretion of testosterone in rat testicular interstitial cells

Evodiamine, a bioactive component isolated from the Chinese medicine Wu- chu-yu, exhibits vasodilative and antianoxic action. Although evodiamine indeed has many biological effects, its effects on the endocrine system are not clear. The present study explored the effects of evodiamine on testosterone secretion in vitro. Rat collagenase-dispersed testicular interstitial cells (TICs) were incubated with evodiamine (0 to 10^-4 mol/L) in the presence or absence of human chorionic gonadotropin (hCG), forskolin, 8-bromo-adenosine 3':5'-cyclic monophosphate (8-Br-cAMP), or steroidogenic precursors (including 25hydroxycholesterol, pregnenolone, progesterone, 17α- hydroxyprogesterone, and androstenedione) at 34°C for 1 hour. The testosterone concentration in the media samples was measured by radioimmunoassay. Evodiamine 10^-4 mol/L was effective to reduce both basal and hCG-stimulated testosterone secretion in rat TICs after 1,2, or 4 hours of incubation. The stimulatory effect of forskolin on testosterone release in TICs was prevented by administration of evodiamine. Evodiamine 10^-4 mol/L also decreased 8-Br-cAMP- and androstenedione-stimulated testosterone secretion. These results suggest that evodiamine reduces testosterone secretion in rat TICs via a mechanism involving reduced activity of cAMP- related pathways and 17β-hydroxysteroid dehydrogenase (17β-HSD).