模拟失重后再超重对猴咬肌细胞SERCA mRNA表达的影响

Effects of high +Gx exposure after simulated weightlessness on the expression of SERCA mRNA in masseter muscle of rhesus macaque

目的:探讨模拟失重后再超重环境对猴咬肌细胞SERCA1a、SERCA2a mRNA表达的影响。方法:健康雄性猕猴23只,随机分为正常对照组(A组)和实验组:模拟失重(B组),模拟超重(C组),失重后再超重分别为+11Gx/270s(D1组)、+13Gx/230s(D2组)、+15Gx/200s(D3组)和+13Gx/230s恢复第10d(D4组)。实验期间,各组喂养条件相同,在实验结束后动物恢复第2d(A、B、C、D1、D2、D3组)和恢复第10d(D4组)处死取材,组织置于液氮中保存。采用常规方法制作冰冻切片,通过HE染色观察猴咬肌细胞组织形态学变化;使用RT-PCR方法检测猴咬肌细胞SERCA1a、SERCA2a mRNA的表达。结果:组织病理学观察可见,对照组猴咬肌细胞结构正常;实验组咬肌细胞胞膜边界模糊不清,间质增宽;模拟失重后再超重组肌细胞肿胀,偶见细胞核呈扁平状,移位胞浆中央。采用RT-PCR检测发现,各实验组与对照组相比,猴咬肌细胞SERCA1a mRNA表达均增强,SERCA2a mRNA除D4组外,其他实验组表达增强,其差异有统计学意义(P<0.05);D2、D3组与B组相比,SERCA1a mRNA表达升高,差异显著(P<0.01);D2、D3组与C组比较,SERCA1a mRNA表达增强,有显著差异(P<0.01);D4组与D2组比较,SERCA1a、SERCA2a mRNA表达均下降,有统计学意义(P<0.05)。结论:模拟失重、模拟超重和模拟失重后再超重环境均可造成猴咬肌细胞组织形态学不同程度地改变,并可引起SERCA1a、SERCA2a mRNA表达增强,其中模拟失重后再超重恢复第10d咬肌细胞组织形态学趋于正常结构,SERCA1a、SERCA2a mRNA表达呈恢复下降趋势。

Objective：To investigate the effects of high ＋Gx exposure after simulated weightlessness on the expressions of SERCA1a、SERCA2a mRNAs in masseter muscle of Rhesus macaque. Methods： 23 male Rhesus macaques were randomly divided into four groups： control group（A）, simulated weightlessness group（B）, simulated overweight group（C）and high ＋Gx exposure after simulated weightlessness group（D）. The D group was further divided into four subgroups according to the Gx loads and duration, including ＋11Gx/270s（D1）, ＋13Gx/230s（D2）, ＋15Gx/200s（D3） and 10 th days recovery after exposure in ＋13Gx/230s（D4） respectively. Masseter muscle was sampled on the second day of the treatment except D4 group, which was sampled on the 10 th day after the treatment. Then the masseter muscle of each group was determined by using HE staining and RT-PCR. Results：1） For the histopathological observation, masseter muscle cells of control group showed normal cell structure, and the sarcolemma of the experimental groups showed fuzzy boundaries. Interstitial space were sparse slightly and some muscle cells were swelled. Occasionally nucleus was flat or shifted in the center; 2） Compared with that of the control group, the expression of SERCA1 a mRNA in masseter muscle of each experimental group increased. Except for D4 group, the expression of SERCA2 a mRNA showed a gradual increase, and the difference was statistically significant（P〈0.05）; Compared with simulated weightlessness group, the expression of SERCA1 a mRNA in the D2/D3 groups showed an increase, and the difference was statistically significant（P〈0.01）. As compared with that of simulated overweight and simulated weightlessness group, the expression of SERCA1 a mRNA in the D2 and D3 groups showed statistically difference（P〈0.01）. However, as compared with D2 group, the expression of SERCA1a/SERCA2 a mRNA in masseter muscle of D4 group decreased significantly（P〈0.05）. Conclusion： Simulated weightlessness group, simulated overweight group and high ＋Gx exposure after simulated weightlessness group can cause the pathological change of masseter muscle cells of Rhesus macaque, and SERCA1a/SERCA2 a mRNA expression can be increased. However, the 10 th day recovery can offer a time for the expression of the SERCA1a/SERCA2 a mRNAs to restore and thereby improve the contraction of the masseter muscle.