The Effect Of Cystamine On PTEN And RhoA Expression In Rat Ischemia-reprefusion Cerebral Cortex

Objective To study the effect of Cystamine on the expression of PTEN and RhoA and apoptosis in global ischemia-reperfusion cerebral cortex.Methods The transient global cerebral ischemia model was induced by four-vessel occlusion.104adult male Sprague-Dawley rats(body weight:280-320g) were randomly divided into the sham-operation group(n=8), the global ischemia group(n=48) and the global ischemia with Cystamine treatment group(n=48). The two posterior groups were randomly divided into six subgroups(n=8) respectively, according to the different time points(6h,12h,1d,3d,5d,7d). The rats in GI+CYS group were treated intraperitoneally with Cystamine(150mg/kg)10minutes after ischemia, then they were given Cystamine every24h after ischemia. Rats in GI group were given the same volume normal saline(NS), which was injected at the same time point. The rats in GI and GI+CYS groups were decapitated respectively at6h,12h,1d,3d,5d,7d after global ischemic-reperfusion injurys. Eight rats in sham group were given normal saline(1ml) and decapitated after3days. The change of neurons apoptosis level was determined by TUNEL, and the expression of PTEN and RhoA was detectde by Immunohistochemistry(SP).Results1) TUNEL The number of positive cells in TUNEL was significantly increased after global cerebral ischemic-reperfusion injury. To compare with the sham group, the positive cells were obviously increased in1d,3d,5d,7d subgroups of global cerebral ischemia group(p<0.01),whiel the positive cells were distinctly lower in Id,3d,5d,7d subgroups of Cystamine treatment group than those in the global ischemia group(p<0.01).2) Immunohistochemistry RhoA immunoreactivities were significantly enhanced following global cerebral ischemia. The expression of RhoA increased at6hours after ischemic-reperfusion, peaked at72hours and continued to7days. Compared with sham group, RhoA immunoreactivities distinctly increased in12h,1d,3d,5d,7d subgroups of global cerebral ischemia group(p<0.01),While the RhoA immunoreactivities were obviously decreased in12h,1d,3d,5d,7d subgroups of Cystamine treatment group than those in global cerebral ischemia group(p<0.01,p<0.05). The expression of PTEN in cerebral cortex was also enhanced after global cerebral ischemia-reperfusion injury.The PTEN immunoreactivities began to upregulate at1days, peaked at3days and lasted to7days. Compared with the global cerebral ischemia group, the expression of PTEN weakened in1d,3d,5d,7d subgroups of Cystamine treatment group(p<0.01).Conclusion After global cerebral ischemic-reperfusion injury, the number of apoptotic cells increased and the expression of PTEN and RhoA enhanced in cerebral cortex, which demonstrate that the neuronic apoptosis may related with the effect of PTEN and RhoA after ischemic-reperfusion injury. Cystamine can effectively reduce the number of apoptotic cells and inhibit the increase of PTEN and RhoA levels, which may be one mechanism of its protecting neurons from ischemic-reperfusion mjurys.