Stage Specific Identification of the Expression of GnRH mRNA and Localization of the GnRH Receptor in Mature Rat and Adult Human Testis

Abstract

Purpose To identify the expression of gonadotropin-releasing hormone (GnRH) messenger ribonuclueic acid (mRNA) and localize GnRH receptors in mature rat and adult human testes. Materials and Methods In situ hybridization and enzymatic receptor binding localization were performed. Results GnRH mRNA was expressed within the seminiferous tubules in both mature rat and adult human testis. In rats, expression of GnRH mRNA was identified in the Sertoli cells and spermatogenic cells of some seminiferous tubules, but the other tubules did not express any hybridization signal. In humans, expression of GnRH mRNA was identified only in some spermatogenic cells in some seminiferous tubules. The receptors for GnRH were localized to cells in the interstitial tissues of the testis, probably Leydig cells. Conclusion The authors believe that the mature rat and adult human seminiferous tubular cells produce GnRH at the same specific stage of the spermatogenic cycle and that GnRH produced within seminiferous tubules, including Sertoli cells and spermatogenic cells, reacts with neighboring GnRH receptors in interstitial cells, including Leydig cells. The GnRH produced from the Sertoli cells in seminiferous tubules would react with GnRH receptors in interstitial cells as a paracrine hormone.