Mechanism of cell autophagy for regulating skeletal muscle wasting of rats after severe burns
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摘要: 目的 探讨细胞自噬调控大鼠严重烧伤后骨骼肌消耗的机制。 方法 取72只SD大鼠,采用随机数字表法分为假伤组、单纯烧伤组、烧伤+磷酸盐缓冲液(PBS)组及烧伤+3-甲基腺嘌呤(3-MA)组,每组18只。单纯烧伤组、烧伤+PBS组及烧伤+3-MA组大鼠造成30%体表总面积Ⅲ度烫伤(以下称烧伤),假伤组大鼠模拟致假伤。伤后即刻,液体复苏后,烧伤+PBS组大鼠腹腔注射1 mL PBS,烧伤+3-MA组大鼠腹腔注射1 mL 3-MA(125 g/L)。伤后3、7 d,称取大鼠右后肢胫骨前肌质量和体质量,计算右后肢胫骨前肌质量百分比;免疫荧光法观察胫骨前肌中微管相关蛋白1(MAP1)轻链3A、Beclin-1的蛋白表达;蛋白质印迹法检测胫骨前肌中Beclin-1及MAP1轻链3A蛋白表达,并计算MAP1轻链3A-Ⅱ/轻链3A-Ⅰ比值。对数据行析因设计方差分析、单因素方差分析、
t 检验及Bonferroni校正。 结果 伤后3、7 d,单纯烧伤组大鼠右后肢胫骨前肌质量百分比分别为(0.148±0.009)%、(0.134±0.018)%,明显低于假伤组的(0.203±0.009)%、(0.181±0.015)%(t =10.585、4.913,P <0.01);烧伤+3-MA组大鼠右后肢胫骨前肌质量百分比分别为(0.187±0.004)%、(0.192±0.009)%,明显高于烧伤+PBS组的(0.162±0.005)%、(0.167±0.005)%(t =9.564、5.948,P <0.01)。伤后3、7 d,单纯烧伤组大鼠胫骨前肌中Beclin-1、MAP1轻链3A蛋白表达量明显高于假伤组,烧伤+3-MA组大鼠胫骨前肌中Beclin-1、MAP1轻链3A蛋白表达量明显低于烧伤+PBS组;单纯烧伤组大鼠胫骨前肌中MAP1轻链3A-Ⅱ/轻链3A-Ⅰ比值明显高于假伤组(t =3.461、3.353,P <0.05),烧伤+3-MA组大鼠胫骨前肌中MAP1轻链3A-Ⅱ/轻链3A-Ⅰ比值明显低于烧伤+PBS组(t =3.129、3.977,P <0.05)。 结论 严重烧伤诱导的细胞自噬参与大鼠骨骼肌消耗进程,抑制细胞自噬可能会有助于缓解烧伤导致的大鼠骨骼肌消耗。Abstract: Objective To investigate the mechanism of cell autophagy for regulating skeletal muscle wasting of rats after severe burns. Methods Seventy-two Sprague-Dawley rats were collected and divided into sham injury group, simple burn group, burn+ phosphate buffer solution (PBS) group, and burn+ 3-methyladenine (3-MA) group according to the random number table, with 18 rats in each group. Rats in simple burn group, burn+ PBS group, and burn+ 3-MA group were inflicted with 30% total body surface area full-thickness scald (hereinafter referred to as burns). Rats in sham injury group were sham injured. Immediately after burns and fluid resuscitation, rats in burn+ PBS group were intraperitoneally injected with 1 mL PBS, and rats in burn+ 3-MA group were intraperitoneally injected with 1 mL 3-MA (125 g/L). On post injury day 3 and 7, the weights of anterior tibial muscle of right hind limbs and body of rats were measured to calculate percentage of anterior tibial muscle of right hind limbs weight. Protein expressions of microtubule related protein 1 light chain 3A (LC3A) and Beclin-1 of anterior tibial muscle were observed by immunofluorescence method and detected by Western blotting, and ratio of microtubule related protein 1 LC3A-Ⅱ to LC3A-Ⅰ was calculated. Data were processed with analysis of variance of factorial design, one-way analysis of variance,t -test and Bonferroni correction. Results On post injury day 3 and 7, percentages of anterior tibial muscle of right hind limbs weight of rats in simple burn group were (0.148±0.009)% and (0.134±0.018)%, respectively, which were significantly lower than those in sham injury group [(0.203±0.009)%, (0.181±0.015)%,t =10.585, 4.913,P <0.01]. Percentages of anterior tibial muscle of right hind limbs weight of rats in burn+ 3-MA group were (0.187±0.004)% and (0.192±0.009)%, respectively, which were obviously higher than those in burn+ PBS group [(0.162±0.005)%, (0.167±0.005)%,t =9.564, 5.948,P <0.01]. On post injury day 3 and 7, protein expressions of Beclin-1 and microtubule related protein 1 LC3A of anterior tibial muscle of rats in simple burn group were significantly higher than those in sham injury group, while protein expressions of Beclin-1 and microtubule related protein 1 LC3A of anterior tibial muscle of rats in burn+ 3-MA group were significantly lower than those in burn+ PBS group. Ratios of microtubule related protein 1 LC3A-Ⅱ to LC3A-Ⅰ of anterior tibial muscle of rats in simple burn group were significantly higher than those in sham injury group (t =3.461, 3.353,P <0.05), while ratios of microtubule related protein 1 LC3A-Ⅱ to LC3A-Ⅰ of anterior tibial muscle of rats in burn+ 3-MA group were significantly lower than those in burn+ PBS group (t =3.129, 3.977,P <0.05). Conclusions Cell autophagy induced by severe burns is involved in the process of skeletal muscle wasting of rats, and inhibition of cell autophagy may contribute to the remission of skeletal muscle wasting of rats induced by burns.-
Key words:
- Burns /
- Autophagy /
- Skeletal muscle wasting /
- 3-methyladenine
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