The Protective Effects Of Cystamine On Neuronal Apoptosis And The Expression Of BDNF,TrkB,Caspase-3 In The Hippocampus After Giobal Cerebral Ischemia In Rats

ObjectiveTo observe the neuronal apoptosis and the expression of BDNF,TrkB,caspase-3 following the global cerebral ischemia in rats,and the treatment effect of cystamine on them,to explore the neuro-protection mechanisms of cystamine.MethodsThe experimental GI model was established by 4-vessel occlusion method and confirmed successfully by an electroencephalogram(EEG).104 adult male Sprague-Dawley rats were randomly divided into sham group(n=8),global cerebral ischemia group(GI,n=48) and global cerebral ischemia+CYS treatment group(GI+CYS,n=48),and the two latter groups to six subsets each with 8 rats.CYS(150mg/kg/day)were administered to rats in GI+CYS group by abdominal cavity injection one time a day.The rats in sham group(n=8) were treated with 1ml saline by abdominal cavity injection and sacrificed 3 days later.The cerebral hippocampus tissues were obtained to make frozen section at 3 days after sham operation in sham group and at 6,12 hours,1,3,5 and 7 days after ischemia-reperfusion in GI and GI+CYS groups.The expressions of BDNF,TrkB,Caspase-3 proteins were detected by Immunohistochemistry(SP),and TUNEL technology was used to detect neuronal apoptosis.The positive neurons were analysised by light microscopy and Image-Proplus 5.0 image analysis system.All data were presented as mean±standard deviation(SD).Data analysis were performed using SPSS13.0 statistical software.A P value less than 0.05 was considered statistically significant.ResultsTUNEL staining:Compared to the sham group,the number of apoptotic cells in subset 1,3,5,7d of GI group and subset 3,5,7d of GI+CYS group were significantly increased(p＜0.05).The number of apoptotic cells in subset 1,3,5,7d of GI+CYS group were significantly less than of GI group.(p＜0.05) Expression of BDNF and TrkB:Compared to the sham group,the expression of BDNF and TrkB were significantly increased in the injured hippocampus in 12h,1,3 subsets of GI group(P＜0.01).Compared to the corresponding subsets of GI group,expression of BDNF and TrkB in subsets 1,3,5d,7d of GI+CYS were significantly higher(P＜0.01).Expression of Caspase-3:Compared to the sham group Gaspase-3 immunopositive cells were significantly increased in the injured hippocampus in6h,12h,1d,3d,5d,7d subsets of GI group(P＜0.01). Compared to the corresponding subsets of GI group,expression level of Gaspase-3 in subsets 1,3,5d,7d of GI+CYS were significantly decreased. (P＜0.01)ConclusionGlobal cerebral ischemia can induce the up-regulation of BDNF and TrkB,which protect injury neuron by initiating cell signal transmission pathway and producing effector molecule.CYS can induce the overexpression of BDNF and TrkB,and inhibit the up-regulation of Caspase-3,which might be one of the mechanisms of the protective effects of CYS on the neurons in hippocampus after GBI.