The lateral habenula is critically involved in histamine-induced itch sensation

Lateral habenula (LHb) is a brain region acting as a hub mediating aversive response against noxious, stressful stimuli. Growing evidences indicated that LHb modulates aminergic activities to induce avoidance behavior against nociceptive stimuli. Given overlapped neural circuitry transmitting pain and itch information, it is likely that LHb have a role in processing itch information. Here, we examined whether LHb is involved in itchy response induced by histamine. We found that histamine injection enhances Fos (+) cells in posterior portion within parvocellular and central subnuclei of the medial division (LHbM) of the LHb. Moreover, chemogenetic suppression of LHbM reduced scratching behavior induced by histamine injection. These results suggest that LHb is required for processing itch information to induce histaminergic itchy response.