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目的探讨新生大鼠缺氧缺血性脑损伤(HIBD)后心肌细胞中Bmal1 mRNA、Clock mRNA及其蛋白合成水平的变化。方法 7日龄新生SD大鼠72只,随机分为HIBD组(实验组)及对照组,HIBD模型按改良Levine法建立,采用RT-PCR和Western Blot法分别测定缺氧缺血后0、2、12、24、36、48h新生大鼠心肌细胞中Bmal1 mRNA、Clock mRNA及其相应蛋白水平。结果实验组Bmal1 mRNA水平在HIBD后48h高于对照组[(0.253±0.043)比(0.178±0.015),P<0.05)],BMAL1蛋白含量水平在HIBD后12h低于对照组,48h高于对照组[12h:(0.426±0.040)比(0.542±0.043),48h:(0.706±0.122)比(0.380±0.110),P<0.05)];实验组Clock mRNA含量水平在HIBD后36、48h高于对照组[36h:(0.591±0.118)比(0.413±0.083),48h:(0.503±0.089)比(0.370±0.089),P<0.05)],CLOCK蛋白含量水平在HIBD后48h高于对照组[(0.715±0.064)比(0.250±0.126),P<0.05)]。其余时间点各项指标在实验组和对照组之间差异均无统计学意义(P>0.05)。结论 HIBD可影响心肌细胞钟基因Clock、Bmal1及其产物的表达。
Objective To investigate the changes of Bmal1 mRNA, Clock mRNA and protein synthesis in neonatal rats after hypoxic-ischemic brain damage (HIBD). Methods Totally 72 newborn SD rats of 7 days old were randomly divided into HIBD group (experimental group) and control group. HIBD model was established by modified Levine method. RT-PCR and Western Blot were used to determine the expression of HIF-1α , 12,24,36,48 h neonatal rat cardiomyocytes Bmal1 mRNA, Clock mRNA and its corresponding protein levels. Results The level of Bmal1 mRNA in experimental group was significantly higher than that in control group at 48h after HIBD [(0.253 ± 0.043) vs (0.178 ± 0.015, P <0.05)]. The level of Bax mRNA was lower at 12h after HIBD and higher at 48h (0.426 ± 0.040) vs (0.542 ± 0.043), 48h: (0.706 ± 0.122) vs (0.380 ± 0.110, P <0.05). The levels of mRNA in the experimental group were higher at 36,48 hours after HIBD The level of CLOCK protein in control group was significantly higher at 48h after HIBD than that in control group [(36.61 ± 0.118) vs (0.413 ± 0.083), 48h: (0.503 ± 0.089) vs (0.370 ± 0.089), P < (0.715 ± 0.064) vs (0.250 ± 0.126), P <0.05)]. The remaining time points of the indicators in the experimental group and the control group differences were not statistically significant (P> 0.05). Conclusion HIBD can affect the expression of clock genes Bcl-1 and its products in cardiomyocytes.