ABSTRACT
AIM: To analyze the effects of salvianolic acid on autophagy and apoptosis of skeletal muscle ischemia-reperfusion injury mice through AKT/mTOR/p70S6K signaling pathway. METHODS: A total of 45 SPF male rats were randomly divided into sham operation group, model group, salvianolic acid group. Model group and salvianolic acid group were prepared for skeletal muscle ischemia-reperfusion injury model. At 72 h, 48 h, 24 h and 15 min before reperfusion, 1 mL of salvianolic acid solution was administered intraperitoneally at a dose of 30 mg/kg. Rats in the sham operation group and the model group were intraperitoneally injected with 1 mL of normal saline. The pathological morphology of the gastrocnemius muscle, the contents of serum CK and LDH, the expression of Akt, p-Akt, p70S6K, p-p70S6K, mTOR and p-mTOR in the gastrocnemius muscle and the expression of Bcl-2 and Bax in the gastrocnemius muscle were observed. RESULTS: At the 0 h, 4 h and 24 h within reperfusion, the W/D ratio of gastrocnemius muscle in the model group were higher than those in the sham operation group. The W/D ratio of the gastrocnemius muscle in the salvianolic acid group was lower than that in the model group (P<0.05). The levels of serum LDH and CK in the model group were higher than those in the sham operation group at 0 h, 4 h and 24 h after reperfusion. The serum levels of LDH and CK in the salvianolic acid group were lower than those in the model group (P<0.05). The expression of Akt protein in the gastrocnemius of the model group was lower than that in the sham operation group, and the expression of p-Akt protein was higher than that in the sham operation group. The protein expressions of Akt, p-Akt, p70S6K, p-p70S6K, mTOR and p-mTOR in the salvianolic acid group were significantly higher than those of the model group (P<0.05). The IOD value quantified the expression of Bax and Bcl-2 protein in the gastrocnemius muscle cells. The Bcl-2 IOD value and Bcl-2/Bax ratio in the model group were lower than those in the sham operation, whlie the Bax IOD value in the model group was higher than that in the sham operation group. The Bcl-2 IOD value and Bcl-2/Bax ratio in the salvianolic acid group were higher than those in the model group, and the Bax IOD value was lower than that in the model group, the difference was statistically significant (P<0.05). CONCLUSION: Salvianolic acid can maintain the homeostasis of Bax and Bcl-2 in bone cells of rats with skeletal muscle ischemia-reperfusion injury and inhibit cell apoptosis. The mechanism may be related to the activation of AKT/mTOR/p70S6K signaling pathway.
ABSTRACT
Hypoxia-inducible factor-1α (HIF-1α) is one of the most potent angiogenic growth factors. It improves angiogenesis and tissue perfusion in ischemic skeletal muscle. In the present study, we tested the hypothesis that ischemic postconditioning is effective for salvaging ischemic skeletal muscle resulting from limb ischemia-reperfusion injury, and that the mechanism involves expression of HIF-1α. Wistar rats were randomly divided into three groups (n=36 each): sham-operated (group S), hindlimb ischemia-reperfusion (group IR), and ischemic postconditioning (group IPO). Each group was divided into subgroups (n=6) according to reperfusion time: immediate (0 h, T0), 1 h (T1), 3 h (T3), 6 h (T6), 12 h (T12), and 24 h (T24). In the IPO group, three cycles of 30-s reperfusion and 30-s femoral aortic reocclusion were carried out before reperfusion. At all reperfusion times (T0-T24), serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities, as well as interleukin (IL)-6, IL-10, and tumor necrosis factor-α (TNF-α) concentrations, were measured in rats after they were killed. Histological and immunohistochemical methods were used to assess the skeletal muscle damage and HIF-1α expression in skeletal muscle ischemia. In groups IR and IPO, serum LDH and CK activities and TNF-α, IL-6, and IL-10 concentrations were all significantly increased compared to group S, and HIF-1α expression was up-regulated (P<0.05 or P<0.01). In group IPO, serum LDH and CK activities and TNF-α and IL-6 concentrations were significantly decreased, IL-10 concentration was increased, HlF-1α expression was down-regulated (P<0.05 or P<0.01), and the pathological changes were reduced compared to group IR. The present study suggests that ischemic postconditioning can reduce skeletal muscle damage caused by limb ischemia-reperfusion and that its mechanisms may be related to the involvement of HlF-1α in the limb ischemia-reperfusion injury-triggered inflammatory response.