NEUROPEPTIDE-MEDIATED COMMUNICATION NETWORKS IN THE HUMAN ARCUATE NUCLEUS

The arcuate nucleus (ARC) coordinates metabolic, endocrine, and reproductive functions, yet its neuronal diversity and signaling organization remain incompletely defined. We performed single-nucleus RNA sequencing on microdissected ARC tissue from eight neurologically healthy donors. Integration with a curated human hypothalamus reference using scArches identified 930 neurons with validated ARC identity. Reference-guided clustering resolved 28 neuronal classes and 55 transcriptionally distinct subtypes. Marker-based matching revealed broad correspondence with reference ARC populations, while a small OTX2-enriched cluster showed limited similarity. Subclustering maintained major identities while revealing differences in neuropeptide and receptor expression. Hierarchical clustering of pseudobulk profiles identified 14 higher-order transcriptional modules, indicating mesoscale organization. Neurotransmitter mapping revealed predominantly GABAergic structure with additional glutamatergic and mixed groups. CellChat analysis decomposed the arcuate connectome into four communication patterns based on ligand–receptor topology. Overlaying neuropeptide and receptor repertoires revealed distinct functional specializations. One module showed broad SST-, NPY-, GAL-, and NTS-associated signaling along with PNOC and AVP co-expression and diverse receptor expression. Another module was enriched for KISS1–tachykinin, NPPC, and enkephalin signaling with prominent TACR3, melanocortin, and gonadotropin-releasing hormone receptors. A third module was mainly involved in POMC- and CART-associated signaling with strong receptive capacity mediated by NPY and orexin receptors. The fourth module showed prominent PACAP and NPPC signaling with enrichment of opioid and RFamide receptors. These data establish a high-resolution, regionally validated molecular and signaling atlas of the human arcuate nucleus, revealing how neuropeptide specialization and secreted signaling regulate ARC circuitry and indicating prospective targets for endocrine and metabolic disorders.