Exogenous visfatin suppresses pituitary gonadotrophins and stimulates testosterone secretion in a male mouse.

Abstract

Visfatin expression has been shown in the testis and pituitary. However, the role of visfatin in the pituitary and testis axis is fragmentary. Furthermore, no study has shown the effects of visfatin on the pituitary gonadotrophins and testicular steroid hormonal secretions in a male mouse. The present study has investigated the effects of exogenous visfatin (most likely a state of hypervisfatinemia) on the gonadotrophins, testosterone, estradiol, androstenedione, and progesterone in a male mouse. The exogenous visfatin was given for 35 days, which covers one spermatogenic cycle. The circulating testosterone was elevated after visfatin treatment, along with down-regulation of AR and steroidogenic markers in the testis. However, the expression of CYP17 was up-regulated in visfatin-treated testis. Visfatin treatment also elevated apoptosis in the different germ cells of the testis. The levels of circulating LH and FSH were also suppressed after visfatin treatment. The immunolocalization of AR exhibited decreased abundance in the pituitary of visfatin-treated mice; thus, it can be suggested that pituitary gonadotrophins secretion might be suppressed by direct action of visfatin rather than via elevated testosterone. In conclusion, our results showed that exogenous visfatin suppresses gonadotrophins and stimulates testicular testosterone secretions in a differential manner. Visfatin has inhibitory effects on pituitary gonadotrophins secretion and stimulatory effects on testosterone secretion from the testis. Thus, conditions similar to hypervisfatinemia likely impair the release of hormones from the pituitary and testis.