Effect of electroacupuncture in alleviating central post-stroke pain in mice by inducing silent information regulator 1-dependent autophagy

Objective  To explore the effect of electroacupuncture on central post-stroke pain (CPSP) and its relationships with silent information regulator 1 (SIRT1) and autophagy in mice.

Methods  Forty male specific pathogen free (SPF) grade healthy male ICR mice were selected, and were randomly divided into Sham group, CPSP group, CPSP + electric acupuncture group (EA group) and CPSP+electroacupuncture +SIRT1 inhibitor EX527 group(EA+EX527group), with 10 mice in each group. CPSP model was induced in mice by injection of type VI collagenase in the nucleus ventralis posterolateralis thalami. The mice in the EA group and the EX527+EA group were stimulated at Neiguan, Renzhong and Sanyinjiao acupoints by frequency of condensation and rarefaction wave of 2/15 Hz at 24 h after modelingfor 30 min per day, lasting for 14 d and the EA+EX527 group was intraperitoneally injected 5 mg/kg EX527 at 30 min before each stimulation. Before the modeling (T₀) and 3, 7 and 14 days (T₁, T₂ and T₃, respectively) after the establishment of the model, the paw withdrawal frequency (PWF), thermal withdrawal latency (TWL) and cold withdrawal latency (CWL) of each group were measured. The mice were sacrificed and brains were collected after pain behavioral tests. The brain water content was measured using dry-humid weight method, and the expressions of SIRT1, Beclin-1 and p62 were analyzed by western blotting.

Results  Compared with the Sham group, the PWF was significantly increased, the TWL and CWL were significantly shortened, the brain water content increased, the expressions of SIRT1 and Beclin-1 in brain tissue were down-regulated, and the expressions of p62 in brain at T₁, T₂ and T₃were up-regulated in the CPSP group, EA group and EA+EX527 group (P < 0.05). Compared with the CPSP group, the PWF, TWL and CWL in the EA group showed no significant change at T₁ (P>0.05). The values of PWF were significantly increased at T₂ and T₃ in the EA group, and the TWL and CWL were significantly prolonged, water content in the brain decreased, the expressions of SIRT1 and Beclin-1 were up-regulated, and the expression of p62 in brain was down-regulated in the EA group compared with the CPSP group (P < 0.05). Compared with the EA group, the PWF, TWL and CWL in the EA+EX527 group showed no significant changes at T₁ (P>0.05). The values of PWF were significantly increased at T₂ and T₃ in the EA+EX527 group, and the TWL and CWL were significantly shortened, water contentin the brain increased, the expressions of SIRT1 and Beclin-1 were down-regulated, and the expression of p62 in brain was up-regulated compared with the EA group (P < 0.05).

Conclusion  Electroacupuncture can promote autophagy via increasing the expression of SIRT1, thereby alleviating central post-stroke pain in mice.