Selective role of neuropeptide Y receptor subtype Y2 in the control of gonadotropin secretion in the rat

Different signals with key roles in energy homeostasis regulate the reproductive axis. These include neuropeptide Y and polypeptide YY3-36, whose type Y2 receptor is the most abundant of this family in the brain. We evaluated herein the putative roles of Y2 receptors in the control of gonadotropin secretion by means of central administration of PYY13-36 (agonist of Y2 receptors) and BIIE 0246 (antagonist of Y2 receptors) to intact and orchidectomized male rats. In addition, the ability of PYY13-36 to elicit GnRH and gonadotropin secretion in vitro and the impact of fasting on LH responses to PYY13-36 in vivo were also monitored. Central administration of PYY13-36 significantly decreased the circulating levels of both gonadotropins, an effect that was observed in prepubertal and adult rats. Yet a dual action of Y2 receptors in the control of male gonadotropic axis was evidenced as their activation induced 1) stimulation of gonadotropin responses to GnRH at the pituitary but 2) inhibition of GnRH secretion ...