Direct inhibition of arcuate kisspeptin neurones by neuropeptide Y in the male and female mouse

Abstract

Adverse energy states exert a potent suppressive influence on the reproductive axis by inhibiting the pulsatile release of gonadotrophin-releasing hormone and luteinising hormone. One potential mechanism underlying this involves the metabolic-sensing pro-opiomelanocortin and agouti-related peptide/neuropeptide Y (AgRP/NPY) neuronal populations directly controlling the activity of the arcuate nucleus kisspeptin neurones comprising the gonadotrophin-releasing hormone pulse generator. Using acute brain slice electrophysiology and calcium imaging approaches in Kiss1-GFP and Kiss1-GCaMP6 mice, we investigated whether NPY and α-melanocyte-stimulating hormone provide a direct modulatory influence on the activity of arcuate kisspeptin neurones in the adult mouse. NPY was found to exert a potent suppressive influence upon the neurokinin B-evoked firing of approximately one-half of arcuate kisspeptin neurones in both sexes. This effect was blocked partially by the NPY1R antagonist BIBO 3304, whereas the NPY5R antagonist L152,804 was ineffective. NPY also suppressed the neurokinin B-evoked increase in intracellular calcium levels in the presence of tetrodotoxin and amino acid receptor antagonists, indicating that the inhibitory effects of NPY are direct on kisspeptin neurones. By contrast, no effects of α-melanocyte-stimulating hormone were found on the excitability of arcuate kisspeptin neurones. These studies provide further evidence supporting the hypothesis that AgRP/NPY neurones link energy status and luteinising hormone pulsatility by demonstrating that NPY has a direct suppressive influence upon the activity of a subpopulation of arcuate kisspeptin neurones.

Keywords: GCaMP; GnRH; NPY receptor; kisspeptin; neuropeptide Y.