The Study Of Protective Effect Of Nicardipine On τProtein In Rats With Ischemia Reperfusion

Objective To observe the protective effect of nicardipine on microtubule-associatedτprotein in rats with ischemia reperfusion and the degree of neuronal injuries.Methods Before making four-vessel occlusion model,rats were randomly divided into four groups:sham operated group,drug controlled group,ischemia group and treatment group.Ischemia group and treatment group respectively included five subgroups: 20 min-ischemia,1,6,24 and 48h after reperfusion.In treatment group,nicardipine was administered intraperitoneally at a dose of 1.2mg/kg 15 minutes before ischemia and atevery 8h after reperfusion.In ischemia group,same volume of normal saline was used in same time mentioned above.Sham operated rats were subjected to isolate bilateral common carotid artery and expose of the first cervical vertebrae.In drug controlled group,nicardipine was administered intraperitoneally at a dose of 1.2mg/kg at moment and every 8 h after sham operation.Whole brains were taken at 24h in latter two groups.The change of immunocompetence ofτ protein in brains was assayed by immunohistochemistry.Meanwhile,four types of neurons were counted and percentages were calculated respectively based on the EKE's method of typing neuron. Rectal temperature and values of blood gas analysis were kept in normal range during experiment. Results 1.No difference in rectal temperature and values of blood gas analysis was noted among four groups (P>0.05). 2. Cerebral ischemia reperfusion resulted in degradation ofτ protein.Mean greyness value of immunocompetence ofτprotein was 148.78±4.59 before ischemia ,reduced to 94.84±3.42 at 20min after ischemia,and further decreased with the time of reperfusion (all P<0.01).Treatment with nicardipine could effectively prevent degradation ofτprotein induced by global ischemia reperfusion and mean greyness value of immunocompetence ofτprotein was significantly higher than that in ischemia group at various intervals(allP<0.01).3. In morphological changes of cells,percentage of type A neurons declined sharply and percentage in type D neurons was significantly higher (all P<0.01)in ischemia group,compared with those in control group,In 48h after reperfusion percentage of type A and type D neurons were 10.6% and 66.1% respectively in ischemia group.In treatment group ,percentage of type A and type D neurons were 42.4% and 23.9% respectively .Conclusions Nicardipine is able to protect microtubule-associatedτprotein against degradation in some degree,reduce the degree of neuronal insult and raise the percentage of relatively normal neuron.