丹酚酸对大鼠骨骼肌缺血再灌注损伤的保护

目的：分析丹酚酸通过AKT/mTOR/p70S6K信号通路对骨骼肌缺血再灌注损伤小鼠细胞自噬及凋亡的影响。方法：选取SPF级雄性大鼠45只，随机数字表法分为假手术组、模型组、丹酚酸组，模型组、丹酚酸组制备骨骼肌缺血再灌注损伤模型，丹酚酸组分别在开始实验前72 h、48 h、24 h及再灌注前15 min，腹腔注射剂量为30 mg/kg的丹酚酸溶液1 mL，假手术组和模型组大鼠腹腔注射生理盐水1 mL。观察各组大鼠腓肠肌组织病理形态，血清肌酸激酶（CK）、乳酸脱氢酶（LDH）含量，腓肠肌组织Akt、p-Akt、p70S6K、p-p70S6K、mTOR及p-mTOR蛋白表达及腓肠肌组织内Bcl-2、Bax表达。结果： 再灌注0 h、4 h及24 h时模型组大鼠腓肠肌湿/干重（W/D）比值较假手术组升高，丹酚酸组腓肠肌W/D比值较模型组降低，差异有统计学意义（P<0.05）；再灌注0 h、4 h及24 h时模型组大鼠血清LDH、CK含量较假手术组升高，丹酚酸组大鼠血清LDH、CK含量较模型组降低，差异有统计学意义（P<0.05）；模型组大鼠腓肠肌Akt蛋白表达较假手术组降低，p-Akt蛋白表达较假手术组升高；丹酚酸组大鼠Akt、p-Akt、p70S6K、p-p70S6K、mTOR及p-mTOR蛋白表达较模型组升高，差异有统计学意义（P<0.05）；光密度值（IOD）量化腓肠肌细胞内Bax、Bcl-2蛋白表达，模型组Bcl-2 IOD数值、Bcl-2/Bax比值较假手术组降低，Bax IOD数值较假手术组增加；丹酚酸组Bcl-2 IOD数值、Bcl-2/Bax比值较模型组升高，Bax IOD数值较模型组降低，差异有统计学意义（P<0.05）。结论：丹酚酸可维持骨骼肌缺血再灌注损伤大鼠骨骼细胞Bax与Bcl-2动态平衡，抑制细胞凋亡，其作用机制可能和激活AKT/mTOR/p70S6K信号通路有关。

Protective effect of salvianolic acid on skeletal muscle ischemia-reperfusion injury in rats

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.