A psychological stressor conveyed by appetite-linked neurons.

Mammals exhibit instinctive reactions to danger critical to survival, including surges in blood stress hormones. Hypothalamic corticotropin-releasing hormone neurons (CRHNs) control stress hormones but how diverse stressors converge on CRHNs is poorly understood. We used sRNA profiling to define CRHN receptors for neurotransmitters and neuromodulators and then viral tracing to localize subsets of upstream neurons expressing cognate receptor ligands. Unexpectedly, one subset comprised POMC (proopiomelanocortin)-expressing neurons in the arcuate nucleus, which are linked to appetite suppression. The POMC neurons were activated by one psychological stressor, physical restraint, but not another, a predator odor. Chemogenetic activation of POMC neurons induced a stress hormone response, mimicking a stressor. Moreover, their silencing markedly reduced the stress hormone response to physical restraint, but not predator odor. These findings indicate that POMC neurons involved in appetite suppression also play a major role in the stress hormone response to a specific type of psychological stressor.