大鼠死后骨骼肌细胞核DNA降解的彗星电泳检测

目的探讨彗星电泳检测大鼠死后骨骼肌细胞核DNA降解碎片与死后时间的关系。方法建立SD大鼠死亡模型,18只雌性大鼠断颈处死,在25.1℃分别于死后6、12、24、36、48、60提取大鼠骨骼肌组织进行彗星电泳,荧光显微成像系统采集图像,同时获取多个分析参数(Comet4.0),并进行统计学处理。结果在死后6～48h,彗星尾长(TL)在死后各时间点的均数依次为11.56±0.10、17.76±0.18、18.82±0.21、21.68±0.18和23.33±0.07;Oliver尾矩(TM)在各时间点的均数依次为1.63±0.46;2.12±0.90;2.15±1.03;2.22±0.76;3.35±0.80;尾DNA(TDNA)在各时间点的均数依次为29.57±8.42;32.36±10.92;30.11±12.55;37.81±12.03;54.76±8.60。结论细胞DNA降解随着死后时间的延长而增加;彗星尾长用于推断死后时间优于Oliver尾矩和尾DNA。

Detection of Nuclear DNA Degradation of the Skeletal Muscle Cells of Rat at Postmortem Interval by Comet Assay

Objective To investigate correlation between nuclear DNA degradation of the skeletal muscle cells of rat detected by Comet assay and postmortem interval (PMI). Methods The death model was set up. Eighteen female rats, Spregue-Dawley, were killed by cervical dislocation and put into imitated environment of 25.1°C for 6h, 12h, 24h, 36h, 48h, 60h respectively. Skeletal muscles were sampled at each time point of postmortem. The nuclear DNA degradation was observed by comet assay. The comet images were captured by HITACHI KP-M1E/K-S10 CCD camera and Meteor II image grabber. Kinetic Komet 4.0 software was used to analyze images. The data of detection were analyzed statistically. Results The comet-tail length (TL) shows in turn a significant increase with PMI from 6h to 48h (means: 11.56±0.10; 17.76±0.18; 18.82±0.21; 21.68±0.18; 23.33±0.07 respectively). It showed the increases that Oliver tail moment (TM) (means: 1.63±0.46; 2.12±0.90; 2.15±1.03; 2.22±0.76; 3.35±0.80 respectively) and that the comet-tail DNA (TDNA) (means: 29.57±8.42; 32.36±10.92; 30.11±12.55; 37.81±12.03; 54.76±8.60 respectively) at the same time. Conclusions This study indicates that degradation of nuclear DNA of the skeletal muscles cells of rat increases with PMI from 6h to 48h and that to estimate PMI the change trend of TL is better than of Oliver TM and T DNA.