Structural and functional diversification of gonadotropin inhibitory hormone (GnIH): A crucial hypothalamic neuropeptide

Prior to the identification of a novel RFamide neuropeptide in birds, pituitary gonadotropins, which are driven by gonadotropin-releasing hormone lacked any recognised inhibitory hormone.RFRP dodecapeptide, which is encoded by the neuropeptide VF (npvf) gene, is often referred to as gonadotropin-inhibitory hormone (GnIH) due to its inhibitory impact on the development and maintenance of gonadal glands by reducing gonadotropin production and release which was initially observed in Japanese quail.This hypothalamo-pituitary-gonadal (HPG) axis down-regulation might be common in all vertebrates.This review aims to provide a comprehensive overview of the neuroanatomical distribution of gonadotropin-inhibitory hormone (GnIH) across vertebrate species.It will trace the discovery of GnIH, which was initially identified as part of the RFamide peptide family and explore the presence of GnIH orthologous peptides in various vertebrate groups.The review will compile and synthesize current data on the localization of GnIH neuronal systems and emphasize their role in regulating reproductive processes, energy balance and other physiological functions.