Gonadotrophin-releasing hormone-I and-II stimulate steroidogenesis in prepubertal murine Leydig cells in vitro

Aim: To study the effect and mechanism of gonadotrophin-releasing hormone (GnRH) on murine Leydig cell steroidogenesis. Methods: Purified murine Leydig cells were treated with GnRH-I and-II agonists, and testosterone production and steroidogenic enzyme expressions were determined. Results: GnRH-I and-II agonists significantly stimulated murine Leydig cell steroidogenesis 60%-80% in a dose-and time-dependent manner (P < 0.05). The mRNA expressions of steroidogenic acute regulatory (StAR) protein, P450scc, 3 beta-hydroxysteroid dehydrogenase (HSD), but not 17 alpha-hydroxylase or 17 beta-HSD, were significantly stimulated by both GnRH agonists with a 1.5-to 3-fold increase (P < 0.05). However, only 3 beta-HSD protein expression was induced by both GnRH agonists, with a 1.6-to 2-fold increase (P < 0.05). Conclusion: GnRH directly stimulated murine Leydig cell steroidogenesis by activating 3 beta-HSD enzyme expression.