FIGURE 5.

Selective deletion of Ehmt2 in DRG neurons prevents nerve injury-induced MOR down-regulation and the diminished morphine analgesic effect. A and B, quantitative PCR and Western blotting analyses show the effect of nerve injury on the mRNA and protein levels of MORs in the DRG of G9a conditional KO and WT control mice (n = 8 mice/group). The amount of MOR mRNA and protein was normalized to GAPDH in the same samples, and the mean value of MOR levels in sham control rats was considered to be 1. The ipsilateral L5 and L6 DRG tissues were removed 2 weeks after surgery. C and D, time course of the effects of intraperitoneal morphine (2.5 and 5 mg/kg) on the tactile and pressure withdrawal threshold of SNI mice (n = 9 mice/group). Data are shown as means ± S.E. *, p < 0.05; **, p < 0.01 compared with the sham group or respective baseline control at 0 min. #, p < 0.01 compared with the wild-type sham group at baseline (time 0). Student's t test (A and B) or one-way ANOVA (C and D) was used.