Estrous cycle and Egg release resets inspired by neurodynamics in the circadian pacemaker
Jet lag and shift work disrupt the menstrual cycle and decrease fertility. The circadian pacemaker, the suprachiasmatic nucleus (SCN), is known to modulate ovulation, but the mechanism is unclear. My work explores this connection by tracking the dynamics of vasoactive intestinal peptide (VIP)-expressing neurons in the SCN in freely-behaving mice. We show that SCNVIP activity is time-of-day- and sex-dependent, and estrous-state-dependent in the late afternoon, gating downstream activation of GnRH neurons. Consistent with a light-responsive switch, afternoon light, as well as specific activation of SCNVIP neurons, rescues estrous cycle regularity and egg release in animals in limited-light conditions. Our results reveal the dynamic mechanism by which SCNVIP neurons mediate light responses to regulate estrous states and demonstrate light-induced fertility rescue, a finding with potential therapeutic implications.