The ontogeny of GnIH and KISS‐1 in the female rat hypothalamus

Abstract

The effects of kisspeptin on reproductive development have been well‐documented in the past decade. More recently, a mammalian orthologue of Gonadotrophin Inhibitory Hormone (GnIH), known as RF‐amide‐related‐peptide‐3 (RFRP3), has also been found to affect reproductive function. It has been proposed that GnIH antagonizes the effect of KISS‐1that upregulates the reproductive system during puberty. In the current study, differential expression of kisspeptin and RFRP3 were examined in the hypothalamic of female rats at various stages of postnatal development. Hypothalamic samples from rats at days 10, 20, 30, 40, 50, and 60 were examined for gene expression of GnRH, GnIH, KISS‐1 and the receptors GPR147 and GPR54. GnRH was expressed very early and its expression was maintained throughout the experiment. GnIH and KISS‐1 expression was greatest on day 30 and then declined during the transition into puberty. These data suggest that perhaps GnIH is up‐regulated once the hypothalamus has fully developed and is prepared for reproduction but is inhibiting reproductive function until other signals from the reproductive axis provide feedback that oogenesis is also complete. This research was supported by the Lander University Foundation Grant.