ABSTRACT
<p><b>AIM</b>To study the effect and mechanism of gonadotrophin-releasing hormone (GnRH) on murine Leydig cell steroidogenesis.</p><p><b>METHODS</b>Purified murine Leydig cells were treated with GnRH-I and -II agonists, and testosterone production and steroidogenic enzyme expressions were determined.</p><p><b>RESULTS</b>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, 3beta-hydroxysteroid dehydrogenase (HSD), but not 17alpha-hydroxylase or 17beta-HSD, were significantly stimulated by both GnRH agonists with a 1.5- to 3-fold increase (P < 0.05). However, only 3beta-HSD protein expression was induced by both GnRH agonists, with a 1.6- to 2-fold increase (P < 0.05).</p><p><b>CONCLUSION</b>GnRH directly stimulated murine Leydig cell steroidogenesis by activating 3b-HSD enzyme expression.</p>