Coupling of oxytocin and cholecystokinin pathways in the hypothalamus is required for gut-to-brain homeostatic feeding control

Summary Oxytocin-expressing paraventricular hypothalamic neurons (PVN OT neurons) integrate afferent signals from the gut including cholecystokinin (CCK) to adjust whole-body energy homeostasis. However, the molecular underpinnings by which PVN OT neurons orchestrate gut-to-brain feeding control remain unclear. Here, we show that mice undergoing selective ablation of PVN OT neurons fail to reduce food intake in response to CCK and develop hyperphagic obesity on chow diet. Notably, exposing wildtype mice to a high-fat/high-sugar (HFHS) diet recapitulates this insensitivity towards CCK, which is linked to diet-induced transcriptional and electrophysiological aberrations specifically in PVN OT neurons. Restoring OT pathways in DIO mice via chemogenetics or polypharmacology sufficiently re-establishes CCK’s anorexigenic effects. Lastly, by single-cell profiling, we identify a specialized PVN OT neuronal subpopulation with increased κ-opioid signaling under HFHS diet, which restrains their CCK-evoked activation. In sum, we here document a novel (patho)mechanism by which PVN OT signaling uncouples a gut-brain satiation pathway under obesogenic conditions.