严重烧伤大鼠骨骼肌细胞凋亡的初步研究

目的 探讨严重烧伤后大鼠骨骼肌细胞凋亡状况,以了解其对骨骼肌萎缩的可能作用机制.方法 100只雄性Wistar大鼠被随机分为假伤组和烫伤组;各组又分为伤后1、4、7、10、14 d 5个时间点,每个时间点10只.制备大鼠40%总体表面积m度烫伤模型,于伤后各时间点称体重和胫骨前肌重量.取后肢胫骨前肌,用透射电镜观察骨骼肌细胞凋亡的超微结构变化,用原位末端缺刻标记法(TUNEL)及免疫组化双标检测骨骼肌组织凋亡细胞核.结果 与假伤组比较,严重烫伤后大鼠体重及胫骨前肌重量从伤后1 d起即开始下降,4 d时达到最低(P<0.05和P<0.01),7 d后体重及胫骨前肌莺量开始缓慢上升,但差异仍有统计学意义(P均<0.01).电镜下观察烫伤组骨骼肌可见少部分细胞核核膜皱缩,染色质边集、断裂,核周区域肌丝降解,部分近核胞膜呈泡状突起,而同一骨骼肌细胞的其他核可显示为正常结构.TUNEL检测也发现烫伤组骨骼肌有散在的阳性细胞核,而假伤组骨骼肌细胞核则未见凋亡改变.结论 严重烧伤大鼠骨骼肌细胞存在凋亡现象,这可能是骨骼肌萎缩的原因之一.

Preliminary study of skeletal muscle apoptosis after severe thermal injury in rats

Objective To investigate changes in skeletal muscle apoptosis after a severe thermal injury in rats.Methods One hundred Wistar rats were randomly divided into two groups:sham thermal injury group and severe thermal injury group.They were subdivided into 1,4,7,10,14 days post-injury with 10 rats in each subgroup.Rats in severe thermal injury group were subjected to a 40%total body surface area full-thickness scald injury.Both weight and tibialis anterior(TA)mass of rats were weighed on 1,4,7,10, 14 days post-injury.Electron microscope was used for observing ultrastructural changes in skeletal muscle, including apoptosis.Tissues of tibialis anterior from burn and sham burn animals were then examined by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and immunohistoehemistry.Results Compared with sham thermal injury group,body weight and TA mass of rats were decreased from first day on,and it dropped to the lowest level at 4 days(P<0.05 and P<0.01), and started to regain from 7 days on(all P<0.01).Electron micrographs showed condensation of chromatin around the periphery of the nucleus,blebbing of the sarcolemma,and free of myofibrils near myonuele in a large area in skeletal muscle of thermally injured rats.Sporadic TUNEL positive myonuclei were also seen under light microscope in skeletal muscle in thermal injury group.There were no characteristic signs of apoptosis in skeletal muscle in rats of sham group.Conclusion There are skeletal muscle apoptosis after severe thermal injury.It may contribute to atrophy of skeletal.muscle after burn injury in rats.