Kisspeptin neurons in the ovine arcuate nucleus and preoptic area are involved in the preovulatory luteinizing hormone surge

Abstract

Kisspeptin is the product of the Kiss1 gene that regulates GnRH secretion. In sheep, Kiss1 mRNA-expressing cells are found in the preoptic area (POA) and arcuate nucleus (ARC), and expression is up-regulated in the caudal ARC during the periovulatory period. We hypothesized that kisspeptin neurons in the ARC are activated by estradiol-17β prior to the preovulatory LH surge. Ovariectomized ewes were treated as follows: 1) estradiol-17β implants (sc 2 wk) to cause tonic negative feedback; 2) vehicle (no estrogen negative or positive feedback); or 3) positive feedback/GnRH surge-inducing injection of estradiol-17β (50 μg iv). For groups 2 and 3, brains were collected 1 h after treatment and kis..