Distinct lateral hypothalamus GABAergic projections regulate sensory and affective dimensions of pain

Pain encompasses both sensory discrimination and affective evaluation, yet the precise behavioral and neurobiological mechanisms of this well-conserved phenomenon are still incompletely understood. Although the lateral hypothalamus area (LHA) has been implicated in nociceptive modulation, its underlying circuitry and causal mechanisms remain elusive. In this study, formalin-induced pain-like behaviors in mice were associated with attenuated activity in LHA ^GAD2-positive neurons, a pattern also observed during acute restraint stress in adult male transgenetic mice. Chemogenetic activation of LHA ^GAD2 neurons significantly alleviated formalin-evoked nociceptive responses and reduced aversive behavioral phenotypes. Additionally, functional analyses revealed a GABAergic projection from the LHA to the lateral habenula that selectively mitigated affective disturbances in a neuropathic pain model. In parallel, projections from LHA ^GAD2 neurons to specific neuronal subsets within the ventrolateral periaqueductal gray modulated nociceptive responses under neuropathic pain conditions. These findings delineate a dual-pathway mechanism by which LHA ^GAD2 neurons independently regulate sensory and affective dimensions of pain-like behavior, offering a basis for targeted pain relief. Collectively, the results reveal previously uncharacterized aspects of pain processing by discrete LHA GABAergic subpopulations and potentially inform the development of subregion- or cell type-specific therapies for pain management.