[Changes in Bcl-2 and Caspase-3 expressions in cortex of hypoxic preconditioning mice]

The purpose of the present study was to explore the roles of Bcl-2 and Caspase-3 in mouse cortex in hypoxic preconditioning. Blb/c mice were randomly divided into three groups: control group, hypoxic group and hypoxic preconditioning group. Fluorescence intensity of Bcl-2 and Caspase-3 was observed and number of positive cells was counted in parietal cortex by immunofluorescence and confocal laser scanning microscope. Fluorescence intensity of Bcl-2 in the normal group, hypoxic group and hypoxic preconditioning group was 6.2±1.7, 68.5±13.1, 180.6±34.8, respectively, and number of Bcl-2-positive cells was 18.5±4.9, 52.3±10.5, 150.8±24.7, respectively. Fluorescence intensity of Caspase-3 in the control group, hypoxic group and hypoxic preconditioning group was 8.6±2.0, 40.2±8.2, 26.4±6.1, respectively, and number of Caspase-3-positive cells of was 4.3±1.2, 63.6±12.5, 45.7±9.8, respectively. The results showed that the expressions of Bcl-2 in both hypoxic group and hypoxic preconditioning group were significantly higher than that in the control group; and the expression of Bcl-2 in hypoxic preconditioning group was even higher than that in hypoxic group. The expressions of Caspase-3 in hypoxic group and hypoxic preconditioning group were also significantly higher than that in the control group; whereas the expression of Caspase-3 in hypoxic preconditioning group was significantly lower than that in hypoxic group. These results suggest that cortex cells are resistant to apoptosis via increased expression of Bcl-2 and lowered expression of Caspase-3 in the cortex and brain cells are thereby protected during hypoxic preconditioning.