Effect of anti-Mullerian hormone on the regulation of pituitary gonadotropin subunit expression : roles of kisspeptin and its receptors in gonadotroph LβT2 cells

[Abstract.] Anti-Mullerian hormone (AMH) is primarily produced by ovarian granulosa cells and contributes to follicle development. AMH is also produced in other tissues, including the brain and pituitary ; however, its roles in these tissues are not well understood. In this study, we examined the effect of AMH on pituitary gonadotrophs. We detected AMH and AMH receptor type 2 expression in LβT2 cells. In these cells, the expression of FSHβ- but not α- and LHβ-subunits increased significantly as the concentration of AMH increased. LβT2 cells expressed Kiss-1 and Kiss-1R. AMH stimulation resulted in decreases in both Kiss-1 and Kiss-1R. The siRNA-mediated knockdown of Kiss-1 in LβT2 cells did not alter the basal expression levels of α-, LHβ-, and FSHβ-subunits. In LβT2 cells overexpressing Kiss-1R, exogenous kisspeptin stimulation significantly increased the expression of all three gonadotropin subunits. However, kisspeptin-induced increases in these subunits were almost completely eliminated in the presence of AMH. In contrast, GnRH-induced increases in the three gonadotropin subunits were not modulated by AMH. Our observations suggested that AMH acts on pituitary gonadotrophs and induces FSHβ-subunit expression with concomitant decreases in Kiss-1 and Kiss-1R gene expression. Kisspeptin, but not GnRH-induced gonadotropin subunit expression, was inhibited by AMH, suggesting that it functions in association with the kisspeptin/Kiss-1R system in gonadotrophs.