Expression of c-Myc protein in hippocampus of bcl-2 transgenic rats after global cerebral ischemia/reperfusion

Objective To investigate the expression of c-Myc protein in hippocampus of bcl-2 transgenic rats after global cerebral ischemia/reperfusion. Methods Ninety healthy male SD rats were randomly assigned into 3 groups.In ischemia/reperfusion group(IR group,n=30),global cerebral ischemia/reperfusion model was established by 4-VO method.Global cerebral ischemia was performed for 6 min,and then carotid artery blood flow was restored.In sham operation group(SO group,n=30),blood vessels were just exposed but not occluded.In bcl-2 group(n=30),the bcl-2 transgenic rat model was established,and then global ischemia/reperfusion model was induced using the same way as IR group.All animals were executed at 6,12,24,48,72 and 96 h by 4% poly-formaldehyde perfusion.TUNEL and HE staining of brain tissue section were used to observe the morphological change of hippocampus,and detect the expression of c-Myc protein in CA1 and CA3 region of hippocampus,and the number of c-Myc positive nerve cells.All the data were analyzed by SPSS 10.0. Results ①The expression of c-Myc protein was detected in CA1 region in IR group at 6 h after global cerebral ischemia/reperfusion,and peaked at 48 h,and c-Myc protein was mainly localized in cell plasma.The expression of c-Myc protein in CA3 region was weaker than that in CA1 region,and also localized in cell plasma.The expression of c-Myc protein in bcl-2 group was weaker than that in IR group at every time point.②HE staining showed that the number of neuron in CA1 region in IR group decreased at 72 h after global cerebral ischemia/reperfusion,companied with neuron disarrangement,nucleus membrane indistinction and nucleolus disappearance.The changes of neuron in CA3 region were lighter than that in CA1 region.However,the neuron damage in bcl-2 group was not obvious.③TUNEL staining showed that the positive number of apoptosis cell reached the peak at 24-48 h after global cerebral ischemia/reperfusion in CA1 region of hippocampus.The positive number of apoptosis cell in bcl-2 group was less. Conclusion The c-Myc protein could express in both CA1 and CA3 regions of hippocampus after global cerebral ischemia/reperfusion in different intensity and distribution.Bcl-2 could inhibit neuron apoptosis through suppressing the expression of c-Myc.