SAT592 Sexually Dimorphic Modulation Of Arcuate Kisspeptin Neurons Activity In Response To NPY

Disclosure: N.D. Mansano: None. R. Frazao: None. Kisspeptin neurons are part of an intricate brain circuit that receives neuronal inputs related tonutritional status from at least three neuronal populations, including NPY/AgRP and POMC neurons of the arcuate nucleus of the hypothalamus (ARH) and cells in the ventral premammillary nucleus. Its well-known action on the HPG axis, hypothalamic kisspeptin neurons also modulate the activity of specific neurons of the paraventricular and the dorsomedial nuclei of the hypothalamus, regions involved in the regulation of appetite and energy expenditure. However, it is not completely elucidated if NPY can influence the HPG axis through the modulation of kisspeptin neuron activity. To determine the NPY effect in the hypothalamic kisspeptin neurons we performed whole-cell patch-clamp recordings. The hypothalamic slices were obtained from the adult Kiss1/hrGFP female (diestrus-stage) or male mice. Kisspeptin cells located in the arcuate nucleus of the hypothalamus (ARH(kisspeptin)) and at the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeN(kisspeptin)) were recorded. On female mice, ARH(kisspeptin) neurons exhibited a rest membrane potential (RMP) average of -52.5±2.5 mV (-40 to -62 mV) and 1.3±0.2 GΩ input resistance (IR). NPY induced the hyperpolarization of 45% of the ARH(kisspeptin) neurons (n= 9 of 20 cells, out of 9 mice). ARH(kisspeptin) neuron’s RMP hyperpolarization was followed by a significant decrease in IR and frequency of action potentials (fAPS). In the AVPV/PeN(kisspeptin) neurons showed RMP average of -69.6±1.9 mV (-51 to - 88 mV) and IR of 0.8±0.09 GΩ (n=18 cells out of 9 mice). No significant NPY-induced effect was noted when recordings were performed on AVPV/PeN(kisspeptin) cells from female mice. To elucidate if the ARH(kisspeptin) neuron’s hyperpolarization depends on action potentials (APs) mediated by synaptic transmission we further evaluated NPY effects in the presence of TTX and amino acid receptor antagonists (6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10μM), DL-2-amino-5-phosphonopentanoic acid (AP5, 50μM), and picrotoxin (50μM). NPY induced no effect on ARH(kisspeptin) neuron’s RMP, and IR in the presence of TTX and amino acid receptor antagonists. Suggesting that NPY-induced hyperpolarization of ARH(kisspeptin) neurons is an indirect effect. To further verify whether sex must be considered as a biological variable to study the NPY effect, we recorded ARH(kisspeptin) cells from male mice. ARH(kisspeptin) neurons recorded from male mice exhibited RPM average of -55.6±1.5 (-45 to -66 mV) and IR of 1.5±0.15 GΩ (n= 13 cells out of 10 mice). Interestingly, NPY induced no effect on RMP, IR, or fAPs in male animals. In conclusion, our results suggest that NPY-induced hyperpolarization of ARH(kisspeptin) cells depends on AP’s mediate synaptic transmission, as a sex-specific effect. Presentation: Saturday, June 17, 2023