Correlation between neuronal injury and the expression of caspase-3 and caspase-activated deoxyribonuclease and effect of cnspase-3 particular inhibitor after focal cerebral ischemia-reperfusion in rats

Objective To investigate the correlation between neuronal injury and the expression of caspase-3 and caspase-activated deoxyribonuclease (CAD) after focal cerebral ischemia-reperfusion in rats, also to study the effect of caspase-3 particular inhibitor. Methods The focal cerebral ischemia model (occluding middle cerebral artery of the rats) was made by using modified inserting thread method and reperfusion after embolizing for one hour. Using HE staining, TUNEL staining and microscopy to observe the morphological changes of ischemic neurons at six different time points including 6,12,24,48 and 72 h, using immunohistochemistry to observe the changes of caspase-3 and CAD protein in two groups (model group and interfere group). Results There was no significant difference between the two groups using HE staining and microscopy. While there was difference of TUNEL staining positive cells in all time points, except 6 h time point; Both the two groups reached the expression peak of caspase-3 in 24 h, and the number was 2. 360± 0. 318 and 0. 804 ± 0. 206 respectively(t' = 10. 039, P < 0. 01), there was statistical significance from 12 h to 48 h between the two groups ; The expression peak time of CAD protein in two groups was 48 h, and the number was 3.061 ± 0. 567 and 0. 812 ± 0. 240 respectively (t' = 8. 960, P < 0. 01), there was statistical significance from 12 to 72 h between two groups. Conclusions Caspase-3-CAD-DNA degradation is one important way of neuronal injury in cerebral ischemia-reperfusion of rats, caspase-3 inhibitor can protect neuron in a certain degree. Key words: Brain ischemia;  Reperfusion;  Caspase 3 ;  Deoxyribonucleases;  Oligopeptides;  Apoptosis