SAT-006 Selective Ablation Of KNDy Elements In Adult Kiss1 Neurons: Implications For The Pulse Generator Model

Abstract Disclosure: G.A. Stamatiades: None. E. Torres Jimenez: None. I. Lopez: None. V.M. Navarro: None. Hypothalamic kisspeptin (Kiss1) neurons in the arcuate nucleus co-express Neurokinin B and Dynorphin (KNDy neurons) and are essential regulators of reproduction. The KNDy model proposes that coordinated action of neurokinin B (stimulatory) and dynorphin (inhibitory) within these neurons generates kisspeptin pulses that drive GnRH and LH secretion. However, this model has been challenged by observations that mice deficient in individual KNDy elements still display LH pulses and preserved fertility, suggesting possible developmental compensatory mechanisms or redundancy. Using CRISPR-Cas9, we performed adult-onset selective knockdown of Tac2, Tacr3, Pdyn, or Oprk1 in arcuate Kiss1 neurons of female Kiss1cre mice via cre-dependent AAV-mediated gene editing. Tac2 knockdown (KD) mice exhibited significantly prolonged estrous cycles (12.25±1.79 vs 4.97±0.15 days, p=0.0004), as did Pdyn KD mice (7.5±1.8 vs 4.97±0.15 days, p=0.02). Individual KD of Tacr3 and Oprk1 did not alter estrous cycles; however, simultaneous KD of both genes resulted in prolonged cycles (11.66±1.82 vs 4.97±0.15 days, p=0.0002), evidencing a compound effect. Remarkably, all experimental groups maintained normal LH pulse frequency and amplitude in gonad intact and after ovariectomy, despite these disruptions. These findings, together with previously published studies of congenital deletion, support that KNDy neurons may not be the sole mechanism responsible for generating GnRH and LH pulses, with important implications for understanding the neuroendocrine control of reproduction. Presentation: Saturday, July 12, 2025