This family includes both FMRFamide-related peptides andgrowth hormone-releasing peptides.FMRFamide-related peptides are neurotransmitters, hormone-like substances and tumor suppressor peptides []. Neuropeptide RFRP-1 acts as a potent negative regulator of gonadotropin synthesis and secretion. Neuropeptides NPSF and NPVF efficiently inhibit forskolin-induced production of cAMP, but RFRP-2 shows no inhibitory activity. Neuropeptide NPVF blocks morphine-induced analgesia. FMRFamide-related peptides may act in concert with kisspeptin, through opposing affects, to regulate the activity of gonadotropin-releasing hormone (GnRH) neurons across the seasons, leading to an annual change in fertility and the cyclical seasonal transition from non-breeding to breeding season [, , ]. The primary role of growth hormone-releasing peptide (fGRP) is to release GH from the pituitary [].
