Figure 2.

Manipulation of VPL^Glu neurons affects pain perception in mice. (a) Schematic of the experimental procedure. (b) Representative images of the injection site of AAV-CaMKII-hM4Di-mCherry (left) and mCherry-labeled neurons (red) co-labeled with glutamate immunofluorescence (green, right) within the VPL. Scale bars, 200 μm (left) or 20 μm (right). (c) Schematic of virus injection and the recording configuration. (d) Whole-cell recordings showing the effect of CNO on AAV-DIO-hM4Di-mCherry expressing VPL^Glu neurons. (e and f) Representative traces (e) and summarized data (f) of spontaneous spikes in VPL^Glu neurons of sham and SNI 7D mice infected with mCherry or hM4Di-mCherry within the VPL. (g) Effects of chemogenetic inhibition of VPL^Glu neurons on the pain threshold in SNI 7D mice. (h) Schematic of optogenetic experiments in C57 mice. (i) Images showing that the injection site within VPL of AAV-CaMKII-ChR2-mCherry (left) and mCherry-labeled neurons (red) co-localized with glutamate (Glu) immunofluorescence (right). Scale bars, 200 μm (left) or 10 μm (right). (j) Schematic of VPL injection of CaMKII-ChR2-mCherry in C57 mice and recording configuration in acute slices. (k) Sample traces of action potentials evoked by light (473 nm, 20 ms, blue line) recorded from VPL^Glu neurons in acute brain slices. (l) Effects of optogenetic activation of VPL^Glu neurons on the pain threshold in naive mice. All data are means ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001. For detailed statistics information, see Table S1.