Fig. 2

Morphine increases the strength of inhibitory transmission from SST-INs onto fast-spiking (FS) PV-INs in PrL. a Representative fluorescent images of a PrL coronal section from LhX6-EGFP/SST-tdTomato mice. Arrowheads indicate colocalization of PV antibody in EGFP⁺tdTomato⁻ cells. Scale bar, 20 μm. b Percentage of PV⁺ neurons in EGFP⁺tdTomato⁻ cells in PrL (265 PV⁺ cells in total 468 EGFP⁺tdTomato⁻ cells in eight slices from three mice). c Schematic diagram for AAV-DIO-hChR2(H134R)-mCherry injection into PrL of LhX6-EGFP/SST-Cre mice. d Representative traces of light-evoked response from SST-INs onto FS PV-INs in acute slice 12 h after saline or 10 mg/kg morphine injection. e Percentage of FS PV-INs responsive to optogenetic-activated SST-INs (n = 30 cells/five  mice in each group; χ² test). Responsive IPSC amplitudes (f), the 10–90% rise time (g) and the half-width (h) of responsive IPSCs in FS PV-INs after saline or morphine exposure (n = 25–26 cells/five mice in each group; Mann–Whitney U test). i Representative traces of responsive amplitudes of IPSC responses in SST-INs to FS PV-INs connections. Light interval: 100 ms. Paired-pulse ratio (PPR) (j) and the coefficient of variation (k) of FS PV-INs in the PrL of mice injected with saline or morphine (n = 20 cells/five mice in each group; j two-way RM ANOVA by the Bonferroni’s post-hoc test. Number: F_(3,114) = 266.2, P < 0.0001, treatment: F_(1,38) = 8.944, P = 0.0049, interaction: F_(3,114) = 5.394, P = 0.0017; k Unpaired Student’s t test). Data are presented as mean ± SEM; n.s. not significant; *P < 0.05 and ***P < 0.001