Effects Of PKA-CREB Signaling Pathway On Learning And Memory Function After RTMS In Cerebral Ischemia And Its Mechanisms

Part1Effects of high-frequency rTMS on learning and memory of ratswith cerebral ischemiaObjective To investigate the effects of high-frequency repetitive transcranial magnetic stimulation(rTMS) on learning and memory in rats with cerebral ischemia.Methods Thirty healthy male SD male rats were randomly divided into normal，model and rTMSgroup. Reperfusion models with middle cerebral artery occlusion（MCAO）were established. rTMSof20Hz was given to successful models in the rTMS group after MCAO finished for7days.Learning and memory changes of rats were observed with Morris water maze.Result The escape latency in normal group is19.35±12.62s.The escape latency in modelgroup(49.76±13.27s) delayed more than that in normal group (P=0.001). The escape latency inrTMS group (33.13±19.46s) decreased less than that in model group (P=0.017).Conclusions The rTMS of20Hz could promote hippocampus neuronal survival after cerebralischemia and inhibit apoptosis. Its affect on the pathway of PKA-CREB might be one of themechanisms. Part2Effects of high-frequency rTMS on pCREB、bcl-2and bax in thehippocampus of rats with cerebral ischemia and its mechanismsObjective To investigate the effects of high-frequency repetitive transcranial magnetic stimulation(rTMS) on pCREB, bcl-2and bax in the ischemic hippocampus of rats with cerebral ischemia andits mechanisms.Methods A total of thirty-two healthy male SD rats were randomly divided into model, rTMS,rTMS+H89and rTMS+NS group. Reperfusion model with middle cerebral artery occlusion（MCAO）was established. Reperfusion models with MCAO were established after injection ofblocker (H89) or normal saline (NS) into the lateral ventricle in the rTMS+H89and the rTMS+NSgroup respectively. rTMS of20Hz was given to all successful models except the model group for7days. Expression changes of protein kinase A-cyclic adenosine monophosphate response elementbinding protein (pCREB), B cell lymphoma/Leukemia gene2(bcl-2) and bcl2-associated protein X(bax) were investigated between model and rTMS group or rTMS+H89and rTMS+NS group.Results The expression of pCREB and bcl-2in rTMS group increased more than that in modelgroup (P<0.01). The expression of bax in rTMS group decreased less than that in model group(P<0.01). The ratio of bcl-2and bax (bcl-2/bax) in the rTMS group increased more than that inmodel group (P<0.01). The expression of pCREB and bcl-2in blocker H89injection groupdecreased less than that in NS injection group (P<0.01). The expression of bax increased in blockerH89injection group more than that in NS injection group (P<0.01). The ratio of bcl-2and bax(bcl-2/bax) in blocker H89injection group reduced compared with that in NS injection group(P=0.02).Conclusions The rTMS of20Hz could promote hippocampus neuronal survival after cerebralischemia and inhibit apoptosis. Its affect on the pathway of PKA-CREB might be one of themechanisms. Part3Effects of high-frequency rTMS on PSD-95and GAP-43of rats withcerebral ischemia and its mechanismsObjective To investigate the effects of high-frequency repetitive transcranial magnetic stimulation(rTMS) on PSD-95and GAP-43in the ischemic hippocampus of rats with cerebral ischemia andits mechanisms.Methods A total of twenty healthy male SD rats were randomly divided into model, rTMS,rTMS+H89and rTMS+NS group. Reperfusion model with middle cerebral artery occlusion（MCAO）was established. Reperfusion models with MCAO were established after injection ofH89or NS into the lateral ventricle in the rTMS+H89group and the rTMS+NS group respectively.rTMS of20Hz was given to all successful models except the model group for7days.Ultrastructure and expression changes of PSD-95and GAP-43were investigated between modeland rTMS group by transmission electron microscopy and Western Blot respectively. Expressionchanges of pCREB, PSD-95and GAP-43were investigated between rTMS+H89and rTMS+NSgroup.Results①Compared with model group，the expression of PSD-95and GAP-43was increased inthe rTMS group (P <0.01). Observed by transmission electron microscopy, the synaptic volumewas increased, the anterior and posterior electron dense areas of the synapse were widened, and theelectron density was increased together with the synaptic vesicles quantity.②Compared withrTMS+NS group, the expression of pCREB, PSD-95and GAP-43was decreased in therTMS+H89group (P <0.01).Conclusions Repetitive transcranial magnetic stimulation of20Hz could promote PSD-95andGAP-43expression in the ischemic hippocampus after cerebral ischemia. The PKA-CREBpathway might be one of the mechanisms.