Neural Circuit Remodeling Underlying Enhanced Feeding During Pregnancy in Mice

Pregnancy represents a unique physiological state marked by substantial adaptations influencing both behavior and metabolism1. Alterations have been observed across multiple levels--from changes in cellular morphology, synaptic density, and neuroglial interactions to a brain-wide reduction in gray matter volume2-7. While these adaptations are thought to support offspring survival and promote maternal physiological and psychological well-being8, their functional significance remains largely unresolved. In particular, linking localized synaptic plasticity to a broader brain-wide circuit dynamics has posed a major challenge. Using virus-mediated screening in mice, we investigated the pregnancy-induced remodeling of the presynaptic landscape of paraventricular hypothalamic (PVH) oxytocin neurons, a central hub of maternal physiology9,10. Here we show a selective and reversible elimination of excitatory synaptic inputs from the medial preoptic nucleus to PVH oxytocin neurons, displaying region-, cell-type-, and pathway-specificity. This reduction in excitatory drive attenuated the anorexigenic activity of oxytocin neurons during feeding, thereby promoting the increased food intake characteristic of pregnancy. These data demonstrate that the selective suppression of anorexigenic PVH oxytocin neuron activity plays a critical role in appetite regulation during pregnancy. More broadly, our data identify a pregnancy-associated remodeling of hypothalamic neural circuits with direct physiological relevance.