| Objective:This research takes the model of 7-days old rats to construct HIBD, to observe the effectiveness that hypoxic ischemic (HI) takes on apoptosis of rats cardiomyocytes, and to test the expression of Cardiotrophin-1 mRNA and protein level in myocardial tissue, and to test the variation laws of the expression of bcl-2, bax, fas, and Caspase-3 mRNA, so that the relationship among CT-1, related genes of apoptosis, and cardiomyocyte apoptosis will be discovered.Methods:1.Build HIBD model of newborn rats with improved Rice. Use 64 7-days old newborn rats. Randomly divide the sample into 8 groups as sham operation control group,2hr,12 hr,24hr,48hr,72hr,5d, and 7days. with 8 rats each. Observe behavior of rats after HI. Examination the appearance of the brain and heart.2.With Western blot, to investigate the expression of CT-1 protein activity in rat myocardial tissue.3.With reverse transcription-polymerase chain reaction (RT-PCR), the expression of CT-1, bcl-2, bax, fas and Caspase-3 mRNA in myocardial tissue of rats will be tested out.4.Terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) technique is applied to detect the variation of apoptotic cells and to work out the apoptosis index (AI).Results:1. Compared with control group:the rats were agitated;and then they were cyanosis,tachypnea.Some rats appeared convulsion,lethargy or coma. The ligated brain hemisphere of HIBD group showed pallor and edema.The volume was larger than the opposite side. The throb of heart was weak,and the rate was increase,the arrhythmia was occur,and the colour was more dark.2. Compared with control group,2hr after HI, CT-1mRNA and it's expression in myocardial tissue starts to increase, and reach the peak at 48hr (P<0.001), and decline during 72hr to 7d. They had a relationship with each other (p<0.01).3. Compared with control group, in group HI, bax mRNA 2h after HI starts to rise, and reaches the peak at 48hr, then decreases at 72hr and 5d. bcl-2 mRNA 2h after HI begins to decrease, and the expression drastically decreases from 12h to 24h (p<0.01), and reaches the minimum level at 48hr then gradually increases, at last stays the same as the control at 7d. In the HI group, the ratio of bcl-2 to bax gradually decreases from 2h, and gets to the minimum at 48hr, and gradually increases from 72hr to 5d, and stays the same as the control at 7d finally, no statistically significant. Fas mRNA increases 2h after HI (p<0.01), and adds up significantly from 12h to 48hr, obvious difference compared with the control (p<0.01), and reaches the peak at 72hr. It decreases at 5d, and is still higher than that in control group at 7d (p<0.01). Caspase-3 mRNA gene expression level increases 2h after HI, and increases significantly from 12h to 48hr (p<0.01), and reaches the peak at 48hr. It decreases from 72hr to 5d, and is still higher than that in control group (p<0.01). Without difference with control group at 7d.4. Compared with control group, the number of apoptotic cells of newborn rats starts to increase. From 12hr to 72hr, the AI is significantly (P<0.01) higher in study group than in control group. The number peaks at 72hr, and a decrease at 5d, but it is still higher than that in control group.Conclusion:1. The model that HIBD complicated heart damage was successfully established.2. After HIBD, the expression of CT-1 mRNA and protein level in myocardial tissue increases significantly. It has obvious differences compared with control group, which is a sign that CT-1 may be a reason of myocardial damage in the condition of hypoxic and ischemic.3. The expression of gene bax,fas,Caspase-3 in myocardial tissue increases after HI, gene bcl-2 decreases.the ration of bcl-2 to bax decreases gradually, With AI of myocardial cells increases, there is a correlation with them. It proves that the cardiomyocyte damage is really exists.4. There is a correlation between CT-1 mRNA and apoptosis gene.
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