| Objective: The aim of this study was to observe the protective effect of Nimodipine on the neural apoptosis after global cerebral ischemia-reperfusion injury in rats and to provid experiment basis for the treatment of ischemia-reperfusion with Nimodipine. Ischemia-reperfusion is a common pathology and physiology phenomenon in medicine. It was confirmed that ischemia-reperfusion may occur in many tissue and organs on animals or human. In recent years, as the development of emergency medicine, some patients such as myocardial infarction, shock, cardiopulmonary resuscitation have a higher survival rate than before. Therefore, it is important to explore the mechanism of ischemia-reperfusion injury for reducing its harmful effect and protecting vital organs.Good blood circulation is the assurance for the cells to obtain oxygen or nutrition and discharge metabolite. Blood reduction of any reason can make cells encounter ischemia injury. As early as possible to recover blood is the basic method to reduce harm of ischemia injury, but it is found that after reperfusion, the injury of some cells become even more serious. So, this phenomenon is called ischemia-reperfusion injury. It is viewed traditionally that the cerebral ischemia- reperfusion induceds cellular necrosis in central neural system. Since 1990, people found cerebral ischemia-reperfusion induced neuronal apoptosis, many scholars worked hard on it. In recent years, delayed neuronal death (DND) has become the top topic in studies. It had confirmed that DND is exactly equal to neuronal apoptosis.At present, to search the effective neuron protecting substance is the question which is urgently awaited to be solved in medical research. Nimodipine, as a calcium-channel antagonist, has important brain protection role in theory, but its mechanism is not clear completely. In this experiment, the flow cytometer was used to determin cellular apoptosis rate and expression of Bcl-2 and Bax proteins in hippocampal neurons in rats so as to observe the effect of Nimodipine on the neural apoptosis after global cerebral ischemia-reperfusion injury in rats and explore its possible mechanism.Methods: Fifty-four male Wistar rats were used in this study. The rats weighted 230～250 gram. All rats were divided into three groups at random: sham-operated group (A), control group (B), treated group(C). The control group and the treated group were divided into four groups: 0h,6h,12h,24h which at the different time-spot after ischemia-reperfusion, and each group had 6 rats. Rat model establishment: Four-vessel occlusion (electrical coagulating bilateral vertebral artery and ligated bilateral common carotid artery) was used to establish the model of global cerebral ischemia-reperfusion in the control group and treated group. Anesthesia was induced with 10% chloral hydrate (350mg/kg) by intraperitoneal injection. First, both of the bilateral vertebral arteries were electrically coagulated and after 24 hour, both of the bilateral carotid arteries were occluded for 15 minutes to make rats to be model of ischemia-reperfusion. The vertebral artery was not electrically coagulated and bilateral common carotid artery was not ligated in sham-operated group. The normal saline was injected into abdomen in control groups (5ml/kg each time), the Nimodipine was injected into abdomen in treated groups (1mg/kg each time). On the 48h time-spot after reperfusion all rats were killed and hippocampus was separated from the brain and put into 4℃fridge. The flow cytometry(FCM) was used to determin cellular apoptosis rate and expression of Bcl-2,Bax protein. SAS 6.12 software was used for analysis. Single factor analysis of variance was used for comparison among groups, and differences between each group were statistically analyzed with Dunnett-t test. P<0.05 indicates significant difference.Reusults: 1 Apoptosis percent: Apoptosis percent of sham-operated group was (2.16±0.14), apoptosis percents of control groups were B1 (13.45±2.38), B2 (15.07±0.56),B3 (13.99±1.73), B4 (13.61±1.52); apoptosis percents of treated groups were C1 (3.02±0.26),C2 (4.37±0.55),C3 (5.31±0.37),C4 (8.06±0.74). There were significant differences among these groups. There were significant differences between A/B1, B1/C1,B2/C2,B3/C3,B4/C4. There was no significant difference between A/C1. Inside the control groups, there were no significant differences compared with each other. Inside the treated groups, there were no significant differences between C1/C2,C2/C3, there were significant differences between C1/C3,C1/C4,C2/C4,C3/C4.2 Expression of Bcl-2, Bax protein2.1 Expression of Bcl-2 protein: The means of Bcl-2 protein in control groups were B1 (196.03±103.18), B2 (271.07±90.62), B3 (260.77±90.16), B4 (260.30±95.85); the means of Bcl-2 protein in treated groups were C1 (680.25±57.47), C2 (630.36±59.02), C3 (513.64±34.98), C4 (446.44±34.56). There were significant differences between control groups and treated groups. Inside the control groups, there were no significant differences compared with each other. Inside the treated groups, there were only C1/C4,C2/C4 had significant differences.2.2 Expression of Bax protein: The means of Bax protein in control groups were B1 (765.49±90.59), B2 (753.56±61.41), B3 (752.62±39.37), B4 (742.70±89.53); the means of Bax protein in treated groups were C1 (365.53±42.95), C2 (463.62±40.95), C3 (529.20±49.17), C4 (587.69±29.84). There were significant differences between control groups and treated groups. Inside the control groups, there were no significant differences compared with each other. Inside the treated groups, there were no significant differences between C2/C3,C3/C4, there were significant differences between C1/C2,C1/C3,C1/C4,C2/C4. 3 The ratio between expression of Bcl-2 and Bax protein (Bcl-2/Bax): The Bcl-2/Bax in control groups were B1 (0.26±0.14), B2 (0.36±0.13), B3 (0.35±0.13), B4 (0.36±0.16); in treated groups were C1 (1.88±0.27), C2 (1.37±0.13), C3 (0.98±0.11), C4 (0.76±0.06). There were significant differences between control groups and treated groups. The C1 of treated group was the highest. There were no significant differences between control groups. There was no significant difference between C3/C4 of treated group. There were significant differences between C1/C2,C1/C3,C1/C4,C2/C3,C2/C4.Conclusion: 1 Nimodipine could effectively reduce apoptosis after global cerebral ischemia- reperfusion injury. The mechanism of Nimodipine may be correlation with the increase expression of Bcl-2 protein, and change the ratio of Bcl-2/Bax protein.2 Nimodipine was effective in protecting brain cells from further damage, the effect would be better if begin to use it at earlier time-spot.
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