Has GnRH a direct role in AMH regulation?

Objective Anti-Mullerian hormone (AMH) together with luteinizing hormone (LH) and follicle-stimulating hormone (FSH) plays crucial roles in gonadal functions. However, the possible effects of GnRH on AMH via the hypothalamic-pituitary-gonadal (HPG) axis remain unexplored. We aimed to explore the changes in AMH levels after bolus GnRH stimulation and understand the relationship of AMH with FSH and LH in healthy subjects. Methods Thirty-one prepubertal children (15 males/16 females) and 78 adults (36 males/42 females) were included. We collected basal (0 minute) samples for determining levels of hormones. After GnRH treatment at a dose of 2.5 mu g/kg body weight (maximum of 100 mu g/kg body weight) intravenously, blood was collected at 30 minutes intervals for 120 minutes. Serum LH, FSH and AMH were measured by electrochemiluminometric assays. Results After injection of GnRH, AMH levels were significantly decreased in 30 minutes (P < 0.001) in all groups with parallel increase of FSH and LH. In the second 30 minutes, all hormones levels reversed. There was also a moderate correlation between AMH and FSH (r = -0.430, P < 0.001). Conclusions GnRH lowers serum AMH levels, which have a negative correlation with the increase in gonadotrophins. These data pinpoint GnRH as an important factor of the AMH regulation, leading new opportunities for the understanding of AMH role in reproductive function and dysfunction.