ABSTRACT
Objective To investigate the protective effect of electroacupuncture pretreatment on myocardial ischemia/reperfusion (I/R) injury and its influence on high mobility group box 1 (HMGB1) expression in rats. Methods Sixty Wistar rats were randomly divided into sham operation group, myocardial I/R model group and electroacupuncture pretreatment group by random number table (each n = 20). Myocardial I/R injury model was reproduced by ligating the left ventricular branch coronary artery at about 0.5 cm below the atrial appendage lower margin for 10 minutes to occlude the blood flow, then the ligature was relaxed for 1 hour reperfusion; in electroacupuncture pretreatment group, 7 days before I/R, the electroacupuncture at Neiguan acupoint was applied once daily for 20 minutes till the 7th day when I/R was established. Under light microscope, the pathological changes of myocardial specimen stained by hematoxylin-eosine (HE) method were observed. The myocardial histopathological integral was detected by semi quantitative integral method, and the changes of histological scores in three groups were investigated. The levels of plasma HMGB1, tumor necrosis factor-α (TNF-α), cardiac troponin T (cTnT) were detected by enzyme-labeled immunosorbent assay (ELISA). The expressions of HMGB1, monocyte chemotactic protein-1 (MCP-1), TNF-αmRNA and protein in myocardium were detected by reverse transcription-polymerase chain reaction (PT-PCR) and Western Blot. Results Under light microscope, the myocardial tissue in myocardial I/R model group showed partial fracture of myocardial fibers, large patches of myocardial cell necrosis, hazy boundary, cellular condensation, rupture and dissolution or even disappearance, interstitial edema with a lot of inflammatory cell infiltration; the above myocardial tissue injury in electroacupuncture pretreatment group was significantly milder than that in myocardial I/R model group. Compared with sham operation group, in myocardial I/R model group the HMGB1, TNF-α, cTnT contents and histological score were significantly increased [HMGB1 (μg/L):9.64±1.16 vs. 2.15±0.31, TNF-α(μg/L):91±22 vs. 19±5, cTnT (μg/L):1.50±0.35 vs. 0.07±0.03, histological score:2.5±0.3 vs. 0.0±0.0, all P<0.01], HMGB1, MCP-1, TNF-α mRNA and protein expressions were increased obviously (HMGB1 mRNA: 1.42±0.16 vs. 0.02±0.00, MCP-1 mRNA:0.46±0.06 vs. 0.01±0.00, TNF-αmRNA:0.75±0.04 vs. 0.03±0.00;HMGB1 protein:1.08±0.01 vs. 0.20±0.01, MCP-1 protein:0.92±0.03 vs. 0.40±0.01, TNF-αprotein:1.10±0.02 vs. 0.35±0.01, P<0.05 or P<0.01);compared with myocardial I/R model group, in electroacupuncture pretreatment group, HMGB1 (6.58±0.73), TNF-α (63±19), cTnT (1.15±0.31) levels were significantly decreased (all P < 0.01), HMGB1, MCP-1, TNF-αmRNA and protein expressions were markedly reduced (mRNA expression was 0.74±0.12, 0.18±0.02, 0.10±0.03, and protein expression was 0.40±0.01, 0.36±0.02, 0.50±0.02, respectively all P<0.05), and histological score (1.2±1.0) was remarkably lowered (P < 0.01). Conclusion Electroacupuncture pretreatment may reduce the myocardial I/R injury in rats, and the mechanism may be related to the amelioration of inflammatory response mediated by HMGB1 at late stage.