Fig. 1.

Chemogenetic activation of descending LC-NAergic neurons inhibits acute itch. a. A schematic illustration of the retrograde transduction strategy for hM3Dq expression in descending LC-NAergic neurons. b Representative images of hM3Dq (detected by HA immunostaining, green) and TH (red) expression in LC-NAergic neurons (visualized by TH immunostaining) in mice injected with the two AAV vectors. Scale bar, 200 μm. c Expression of c-FOS (green) in hM3Dq-expressing descending LC-NAergic neurons (visualized by mCherry and TH immunostaining) 2 h after administration of saline or CNO (10 mg/kg, i.p.) to AAV-injected mice. Scale bar, 100 μm. Scratching events induced by intradermal injection of compound 48/80 (50 μg/50 μl, d) or CQ (200 μg/50 μl, e) 20 min after CNO (10 mg/kg) or saline administration to AAV-injected mice (d: saline, n = 7; CNO, n = 8, e: saline, n = 5; CNO, n = 7, ***P < 0.001). Data show the mean ± SEM