Dehydroepiandrosterone-Regulated Testosterone Biosynthesis via Activation of the ERK1/2 Signaling Pathway in Primary Rat Leydig Cells

Abstract

Background: Dehydroepiandrosterone decreases with age and this reduction has been shown to be associated with physical health in human. Some studies have suggested that the effects of DHEA are exerted after it is biotransformed into more biologically-active hormones in peripheral target cells. This study investigated the effects of DHEA on the testosterone biosynthesis and possible signaling pathway mechanism underlying these DHEA effects were also explored in primary rat Leydig cells. Methods: Primary Leydig cells were treated with DHEA and then detected testosterone content by RIA and steroidogenic enzymes, ERK1/2 signal pathway factors protein expression level by Western blot. Results: Incubation of primary Leydig cells with DHEA significantly increased testosterone content and 3β-HSD and 17β-HSD protein expression levels, while aromatase protein expression levels were decreased. Compared with the control group, p-ERK1/2 and p-CREB protein levels were significantly increased in DHEA-treated groups. Testosterone content was significantly decreased in the DHEA-treated group pre-incubated with U0126 (p-ERK1/2 inhibitor). Additionally, the rise in p-ERK1/2, 3β-HSD and 17β-HSD protein levels induced by DHEA was reversed when cells were pre-incubated with U0126. Interestingly, no significant difference was found in aromatase protein expression level in cells pretreated with U0126. Conclusion: These findings demonstrate that (a) exogenous DHEA might preferentially convert to testosterone rather than estradiol due to the up-regulation of 3β-HSD and 17β-HSD protein levels and the down-regulation of aromatase protein level in primary Leydig cells, and (b) the action of DHEA is at least partly associated with the elevation of p-ERK1/2 and p-CREB protein levels.