The Mechanism And Effects Of High Frequency RTMS On Learning And Memory Of Global Cerebral Ischemia In Rats

Objects: The experiment was performed to study learning and memory disorder,the changes of morphology and local field potentials(LFPs)in Hippocampal CA1 area and the expression of PKA and p-CREB protein in rats with global cerebral ischemia.Studying the effects and mechanism of high frequency rTMS on learning and memory of global cerebral ischemia in rats.Methods:(1)A total of 88 SD rats were randomly divided into SO group,MC group,SrTMS group,rTMS group and rTMS+H89 group.Before surgery,rTMS+H89 group was received PKA blockers H89 1ml(5mg/kg)by intraperitoneal injection.(2)All groups were established into global cerebral ischemia model by modified four-vessel occlusion(4-VO)method except SO group.(3)After the modelsweresuccessfully established,rTMS group and rTMS+H89 group were received 10 Hz rTMS stimulation for 2 weeks,SrTMS group was received sham stimulation,MC group was not receivedrTMS stimulation.(4)Before 4-VO and after rTMS treatment,all groups were received Morris water maze test to detect the changes of spatial learning ability of global cerebral ischemia rats.(5)HE staining detected the morphological changes in Hippocampal CA1,multi-channel recording technique detected the changes of Local field potential(LPFs)in Hippocampal CA1 region of theta and gamma oscillation,immunohistochemical method and Western blot detected the expression of PKA and p-CREB protein in Hippocampal of global cerebral ischemia in rats.Results: 1.The results of morris water maze test:Before 4-VO operation,there were no significance difference on the average escape latency,the spanning platform times and the original platform quadrant swimming time between each groups(p>0.05).After rTMS,the average escape latency in MC group was longer than in SO group,the spanning platform times and the original platform quadrant swimming time in MC group were shorter than in SO group(p<0.05).The average escape latency in SrTMS group MC group and rTMS+H89 group was longer than in rTMS group,the spanning platform times and the original platform quadrant swimming time in SrTMS group MC group and rTMS+H89 group were shorter than in rTMS group(p<0.05).There were no significance difference on the average escape latency,the spanning platform times and the original platform quadrant swimming time between MC group and SrTMS group(p>0.05).2.The results of LFPs in Hippocampal CA1 area: The mean power spectral density of ? and ? in MC group was lesser than in SO group(p<0.05).The mean power spectral density of ? and ? in SrTMS group MC group and rTMS+H89 group was lesser than in rTMS group(p<0.05).There is no significance difference on the mean power spectral density of ? and ? between MC group and SrTMS group(p>0.05).3.The results of HE straining in Hippocampal CA1 area: There was no apoptosis or necrosis,nucleus is clearly visible inthe Hippocampal CA1 region in SO group.The cells in Hippocampal CA1 area in MC group had cell apoptosis and necrosis in different stage,performed as arranged in disorder,the cells' number decreased,the nucleus was irregularly shaped,the cytoplasm eosinophilic.The cell necrosis of Hippocampal CA1 area in rTMS group and rTMS+H89 group was lesser than in MC group.The cell necrosis ofHippocampal CA1 area in SrTMS group was almost the same as MC group.4.The results of immunohistochemical staining: The expression of PKA and p-CREB protein in Hippocampal CA1 area in five groups.The expression of PKA and p-CREB protein in Hippocampal CA1 area in MC group were lesser than in SO group and rTMS group(p<0.05).The expression of PKA and p-CREB protein in Hippocampal CA1 area in rTMS+H89 group were lesser than in rTMS group(p<0.05).There were no significance difference on the expression of PKA and p-CREB protein in Hippocampal CA1 area between MC group and SrTMS group(p>0.05).5.The results of Western bolt: The expression of PKA and p-CREB protein in Hippocampal in MC group were lesser than in SO group and rTMS group(p<0.05).The expression of PKA and p-CREB protein in Hippocampal in rTMS+H89 group were lesser than in rTMS group(p<0.05).The expression of PKA and p-CREB protein showed no significant difference in MC group compared with SrTMS group(p>0.05).Conclusion: 1.High frequency rTMS could improve the LFPs of ? and ?of global cerebral ischemia rats.2.High frequency rTMS could improve learning and memory of global cerebral ischemia rats,the mechanism might be rTMS activate PKA-CREB signaling pathway to increase the expression of PKA and p-CREB protein in hippocampal.