Influence of caspase-3 on hippocampal neuronal apoptosis following ischemia-reperfusional injury in rats

Changlin YIN; Jianqiong XIONG; Liang WEN

ABSTRACT

BACKGROUND:

Caspase-3 exists in normal cell in form of zymogen and is capable of stimulating cell apoptosis after activated by apoptosis inducing factors.

OBJECTIVE:

To observe the activity of caspase-3 in hippocampal cytosolic S-100 and neuronal apoptosis in hippocampal regions, so as to discuss the relationship between hippocampal neuronal apoptosis and caspase3 activity during the whole brain ishcemic-reperfuasional injury.

DESIGN:

Randomized controlled experiment.

SETTING:

Emergency Department of Southwest Hospital Affiliated to the Third Military Medical University of Chinese PLA.MATERIALS This experiment was carried out at Southwest Hospital Affiliated to the Third Military Medical University of Chinese PLA from January to April 1999. Totally 182 male Wistar rats were randomly divided into 3 groups namely sham operation group of 14 rats, cerebral IR group of 84, rats acetyl-asp-glu-val-asp-aldehyde (AC-DEVD-CHO) treatment group of 84 rats, rats in the latter two groups were then subdivided into IR 8, 24, 48, 72, 120 and 168 hours time points subgroups with 14 rats in each.

METHODS:

The whole brain ischemia 20 minutes and reperfusional model was established on rats in brain IR group and Ac-DEVD-CHO treatment group, and rats were executed separately at post-reperfusional 8, 24,48, 72, 120 and 168 hours for obtaining hippocampal specimen; rats in sham operation group were only underwent anesthesia and operation without common carotid arterial occlusion and burns of vertebral artery, they were executed at 72 hours after operation and hippocampal specimen was obtained. The quantity of amino-methylcoumarin that was produced from the same mass of specimen within same decomposition time was used to reflect the activity of caspase-3. Brain slices that were obtained from different time points were stained and embedded for observing the hippocampal cell apoptosis under fluorescence microscope at 330-350 nm.MAIN OUTCOME MEASURS ① The caspase-3 activity in hippocampal S-100 in different post-IR time point groups. ② The hippocampal cell apoptosis in different post-IR time point groups. ③ relationship between caspase-3 activity and neuronal apoptosis in hippocampal regions.

RESULTS:

Totally 182 rats were enrolled in this experiment, 14 rats got lost, thereby date of 168 rats was entered the result analysis. ① The changes of caspase-3 activity in hippocampal S-100 in different post-IR time point groups There was no change in sham operation group at postoperative 72 hours. In contrast with cerebral IR group, there were obvious reduction in Ac-DEVD-CHO treatment group at post-reperfusional 24, 48,72, 120 and 168 hours [(1.71±0.03, 1.22±0.03; 2.77±0.09, 1.59±0.7;5.54±0.51, 2.3±0.19, 6.28±1.71, 3.43±0.46; 3.11±1.21, 1.73±0.14) nkat/kg;P ＜ 0.05 or 0.01]. ② The hippocampal cell apoptosis in different post-IR time point groups Under 400× field of vision, the number of apoptotic cells in sham operation group was 1.2±0.4 cells at postoperative 72 hours.It was lower in Ac-DEVD-CHO treatment group at post-reperfusional 24,48, 72, 120 and 168 hours than cerebral IR group [(6.4±1.7, 2.8±0.8;11.8±1.3, 5.8±1.9; 19.8±3.1, 10.0±1.9; 31.2±5.9, 16.4±2.4; 19.8±2.3, 9.0±2.3)cells/400× field of vision; P ＜ 0.01]. ③ Relationship between caspase-3activity and neuronal apoptosis in hippocampal regions It was proved of linear correlation in cerebral IR group and Ac-DEVD-CHO treatment group,displaying significantly positive correlation r= 0.935 6 or 0.980 0, P ＜ 0.01).

CONCLUSION:

Caspase-3 activation is one of the major inducer for hippocampal neuronal apoptosis, playing important role in hippocampus neuronal apoptosis in rats during IR injury.