Fig. 2

Chemogenetic silencing of descending LC-NAergic neurons enhances acute itch. a A schematic illustration of retrograde transduction strategy of PSAM⁴-GlyR expression in descending LC-NAergic neurons. b Expression of PSAM⁴-GlyR (detected by mCherry; red) in LC-NAergic neurons (visualized by TH immunostaining) in mice injected with the two AAV vectors. Scale bar, 200 μm. c–e Effect of varenicline (100 nM)-induced membrane hyperpolarization and spontaneous firing of mCherry⁺ neurons. The representative trace (c) and the summary data (d: RMP, n = 12, ***P < 0.001; e: spontaneous firing, n = 12, **P < 0.01). Scratching events induced by intradermal injection of compound 48/80 (50 μg/50 μl, f) or CQ (200 μg/50 μl, g) 20 min after varenicline (0.5 mg/kg) or saline administration (f: n = 5, g: n = 6, *P < 0.05). Data show the mean ± SEM