Increase of kisspeptin-positive cells in the hypothalamus of a rat model of polycystic ovary syndrome.

Kisspeptin, a hypothalamic neuropeptide, is expressed in the arcuate nucleus (ARC) that is considered as the center of the gonadotropin-releasing hormone (GnRH)-pulse generator. We hypothesized that kisspeptin expressed in the ARC is implicated in the disturbance of the hypothalamus-pituitary-ovary axis observed in polycystic ovary syndrome (PCOS). To test this hypothesis, we evaluated the hormonal profiles, luteinizing hormone (LH) pulse, and ARC kisspeptin immunoreactivity in a PCOS rat model using the anti-progestin RU486. We found an alteration of the LH pulse, including a trend towards an increased mean LH concentration and area under the curve, and a significant upregulation of the mean LH pulse amplitude. Additionally, a higher number of kisspeptin-positive cells was observed in the ARC of RU486-treated rats than in the ARC of intact rats. These results suggest the possible involvement of hypothalamic kisspeptin in the hypothalamus-pituitary-ovary axis and therefore, in PCOS pathophysiology.