Role of ghrelin on testosterone secretion and the mRNA expression of androgen receptors in adult rat testis

Abstract

The present study was designed to determine the effects of ghrelin on in vivo and in vitro secretion of testosterone (T) and the expression of androgen receptor (AR) mRNA in the adult rat testis. The distribution of growth hormone secretagogue receptors (GHS-R1a) in the testis was also investigated. GHS-R1a immunoreactivity presented mainly in Sertoli and Leydig cells, primary spermatocytes, and secondary spermatocytes. Adult rats that were intracerebroventricularly (i.c.v.) administrated different dosages (1 nmol and 3 nmol) of ghrelin could significantly inhibit the secretion of T. The experession of AR mRNA in the testis was also notably reduced with 3 nmol ghrelin. Additionaly, in vitro exposure of the Leydig cells to increasing concentrations of ghrelin resulted in no obvious changes of T secretion in the culture media and AR mRNA expression of Leydig cells. Overall, our data demonstrate that the i.c.v. injection of ghrelin plays a physiological role in T secretion and AR mRNA expression in the testis, further confirming the reproductive role of ghrelin. © 2011 Informa Healthcare USA, Inc.