Expressing Of MMP-2/TIMP-2 And The Effect Of Captopril In Focal Cerebral Infarction Rats

Because of higher incidence of a disease and the rate of death, cerebral infarction is important in cerebrovascular diseases study. The main pathological basis is that the integrity of the vessel wall is damaged. The blood vessel wall consist of basal lamina and endothelial cell and their injury will lead to cerebral infarction. It was reported that the matrix metalloproteinases (MMPs) and the tissue inhibitor of metalloproteinases (TIMPs) play important role in pathological processes of cerebral infarction. MMP-2 play important role in degradation of extracellular matrix (ECM) and TIMP-2 is endogenous inhibitor. Through immunohistochemistry, this study measured MMP-2 and TIMP-2 at multiple times and effect of captopril in focal cerebeal infarction in rats. 40 SD rats is divided into 8 groups at random, its are sham operation, 6, 12 hours, 1, 3, 5, 7 days groups after middle cerebral artery occlusion (MCAO) and MCAO + captopril group. With tying carotid artery and inducing hypoxia, we make a model of focal cerebral infarction SD rats. Methods: Adult SD rats, weighing 250 to 300g, were anesthetized with10% Chlotalhydrat ( 0.3ml/100g).Left carotid artery of rats are exposed and tied, then the rats are placed hypoxic bottle(ratio,N2 92%±5%and O2 8%±1%) 40 minutes. The same was done to sham operation except tying carotid artery and inducing hypoxia. The neurological deficits were assessed by an observer and scored as described previously after rats cleared. 0, no observable neurological deficits; 1,failure to extend left forepaw on lifting the whole body by the tail; 2, circling to the contralateral side; 3, leaning to the contralateral side at rest or no spontaneous motor activity. The model is thought to succeed if score is more than 1. The neurological deficits were assessed before rats were killed in 5 days MCAO. MCAO + captopril group is feed captopril 0.45mg/kg 3 times per day. The rat models were perfused transcardially with 4% paraformaldehyde 0.1MPBS. Brains were removed and kept in paraformaldehyde 0.1MPBS for 4-6 hoursand were subsequently embedded in paraffin. After 2-mm-thick slices were obtained,they were deparaffinized overnight and hudtated in xylol and graded alcohol solusions.sections were stained with anti-nitrotyrosine antibody by the avidin-biotin method. Brain soices were evaluated for mtroty rosine or MMP-2 staining by an observer blinded to the identity of treatment. The results in sham operation group and control group reveal that MMP-2 and TIMP-2 are low level around vessel wall. The time course of MMP protein expression after occlusion of the MCA was assessed in tissue extracts prepared from control and ischemic regions of rat brain. The proteins extracted from the tissues were evaluated by SDS-PAGE before further analysis, and the quality of the extracts was demonstrated to be satisfactory (data not shown). MMP-2 protein expression were evaluated by immunohistochemistry. The results demonstrated that MMP-2 was detected in the ischemic tissue within 12 hours after occlusion and was observed in the ischemic tissue predominantly at the 5-day time point. By day7, however, expression of MMP-2 protein decreases. TIMP-2 increase followed MMP-2 but expression level of TIMP-2 is lower. The results of MCAO + captopril group reveal that MMP-2 expression is lower than that of model group (P<0.05). TIMP-2 expression is not detected (P>.05). The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes whose signature function is the remodeling of the extracellular matrix (ECM). This activity is counterbalanced by another family of molecules know as the tissue inhibitor of the MMPs (TIMPs). The MMPs are a family, which contain some 23 members, of Zn2+-endopeptidases that share many common structural features. These include a propeptide region that, when ligated to Zn2+in the catalytic domain, Vessel basal lamina consist of ECM. MMP-2 is a main MMPs, which can degrade a main component of ECM-Ⅳ collagen. The cells of produce MMP can produce TIMP as wel...