Anti-Mullerian hormone receptor type 2 is expressed in gonadotrophs of postpubertal heifers to control gonadotrophin secretion

Preantral and small antral follicles may secret anti-Mullerian hormone (AMH) to control gonadotrophin secretion from ruminant gonadotrophs. The present study investigated whether the main receptor for AMH, AMH receptor type 2 (AMHR2), is expressed in gonadotrophs of postpubertal heifers to control gonadotrophin secretion. Expression of AMHR2 mRNA was detected in anterior pituitaries (APs) of postpubertal heifers using reverse transcription-polymerase chain reaction. An anti-AMHR2 chicken antibody was developed against the extracellular region near the N-terminus of bovine AMHR2. Western blotting using this antibody detected the expression of AMHR2 protein in APs. Immunofluorescence microscopy using the same antibody visualised colocalisation of AMHR2 with gonadotrophin-releasing hormone (GnRH) receptor on the plasma membrane of gonadotrophs. AP cells were cultured for 3.5 days and then treated with increasing concentrations (0, 1, 10, 100, or 1000 pg mL(-1)) of AMH. AMH (10-1000 pg mL(-1)) stimulated (P < 0.05) basal FSH secretion. In addition, AMH(100-1000 pg mL(-1)) weakly stimulated (P < 0.05) basal LH secretion. AMH (100-1000 pg mL(-1)) inhibited GnRH-induced FSH secretion, but not GnRH-induced LH secretion, in AP cells. In conclusion, AMHR2 is expressed in gonadotrophs of postpubertal heifers to control gonadotrophin secretion.