Figure 3.

Depletion of lPBN^NK1R neurons diminish sustained pain and associated affective memory

A: Schematic of bilateral AAV viral injection to ablate lPBN^NK1R neurons. B: Left and middle, representative images show loss of lPBN^NK1R neurons (GFP, green) after taCasp3 viral injection, with mCherry as a control (red). Right, quantification of loss of GFP⁺ cells in different lPBN subnuclei after viral injection (n=6 mice per group, unpaired t-test for each lPBN subnucleus). Scale bars: 200 μm for lower magnification, 20 μm for insets. C: No significant differences were observed in falling latencies from the rotarod between control and lPBN^NK1R-ablated groups (n=6 mice per group). D–H: Reflexive response tests. No significant differences were observed in withdrawal responses to von Frey filament (D), brush (E), radiant heat (F), dry ice (G), and hot plate (H) stimulation (n=6–7 mice per group). I–K: lPBN^NK1R-ablated mice showed significantly reduced licking behaviors in hot plate (I), skin pinching (J), and toe clipping (K) tests (n=6–7 mice per group). L: Reduced writhing behavior was observed after acetic acid injection in lPBN^NK1R-ablated mice (n=6 mice per group). M: Schematic of skin pinching- or toe clipping-induced conditioned place aversion (CPA) test. N: Skin pinching- (left) and toe clipping-induced (right) CPA in C57BL/6J mice (n=7–8 mice per group). O: Both skin pinching- (left) and toe clipping-induced (right) CPA were lost in lPBN^NK1R-ablated mice (n=7–8 mice per group). Panels B–L, three males and three females in each group, panels N–O, four males and three to four females in each group. Green and red circles represent male and female mice, respectively. Data are mean±SEM, unpaired t-test. ns: No significance; ^**: P<0.01; ^***: P<0.001.