Endocrine Abstracts

Social behaviour is profoundly shaped by bodily states. It is well-documented that individual states such as the estrous cycle or hunger affect behaviours such as mating or aggression. However, animals typically exhibit multiple such states simultaneously. How and where orthogonal states are integrated and how this shapes behaviour remains poorly understood. Here we report how hunger and hormonal state converge on neurons in the medial preoptic area (MPOA) to shape infant-directed behaviour. We first demonstrate that hunger can trigger pup-directed aggression in virgin female mice. This behavioural switch results from the inhibition of MPOA neurons by neuropeptide Y (NPY) release from Agouti-related peptide expressing neurons in the arcuate nucleus of the hypothalamus (ArcAgRP neurons). Next, we show that the rate of aggression is set by hormonal state, with MPOA neurons sensing the progesterone (P4) to estradiol (E2) ratio throughout the estrous cycle. Hunger and hormonal state converge on HCN (hyperpolarization-activated cyclic nucleotide-gated) ion channels, setting the baseline activity and excitability of MPOA neurons. Our findings provide a neural mechanism for the integration of orthogonal physiological states, enabling flexible switching of social behaviour.