| Background: Lithium has been proved to have a neuroprotective effectin recent years. But the underlying mechanisms remains unclear. Ourprevious research has demonstrated that it maybe related to itsdown-regulation of p53 protein, activation of Akt protein, up-regulation ofbcl-2 and HSP70 proteins, in the ischemic brain. Akt can suppress GSK-3β,whose function is to promote cells to apoptosis. So suppressing theactivation of GSK-3βmay be one of important neuroprotective mechanismsof lithium. Lithium can suppress activation of GSK-3βoutside the body, butthe reports about relationship between lithium and GSK-3βin body are veryfew.Objective: Lithium chloride was used after MCAO/reperfusion in rats,(1) in order to observe neuronal apoptosis and the expression and activityof GSK-3βof hippocampal CA1 areas after transient focal cerebralischemia/reperfusion in rats; (2) observe the effect of lithium chloride onneuronal apoptosis and the expression and activity of GSK-3βof hippocampal CA1 areas after transient focal cerebral ischemia/reperfusion inrats.Methods: MCAO models: Occluded the right middle cerebral arteryof rats with a 3-0 nylon suture for 90min,then the nylon suture waswithdrawn and the ischemic brain tissue received blood reperfusion forvarious times before death.126 male SD rats were randomly divided into normal group(NOgroup),sham operation group(SH group), ischemia/reperfusion group(IRgroup), group treated with lmmol/kg lithium chloride(Li1 group), grouptreated with 2mmol/kg lithium chloride(Li2 group),and group treated with3mmol/kg lithium chloride (Li3 group). Six rats were distributed into NOgroup. The last five groups were further divided into four subgroupsrespectively according to the time when they were killed, with six rats ineach subgroup. The rats in normal group (NO group ) had not be given anytreatment before death The rats in every lithium group had be givencorresponding dosage of lithium chlorine through intraperitoneal injectionseparately soon after reperfusion (namely 90 minute under MCAO), Onceevery 24 hours until they were killed. The rats in sham operation group andischemia/reperfusion group had been given the physiological saline of theequal volume through intraperitoneal injection. The change of neuronalapoptosis in the CA 1 region was examined by Hoechst staining. The expression and distribution of GSK-3βand p-GSK-3β(Ser9) in the cell wasexamined by immunofluorescence analysis. All data were expressed as mean±SD, statistical analysis was performed using Stata8.0 and P value of＜0.05was considered significant.Results: (1)Apoptosis: The apoptotic nuclei could be detectedsignificantly in IR groups(Compared with SH groups, P＜0.01). The peakresponse of Hoechst staining occurred around 24 h after MCAO, which wasfollowed by a gradual decline at 3 days and 7 days. Compared to IR groups,groups treating with lithium chloride dose dependently (1～3 mmol/kg)reduced the apoptotic nuclei in happocampal CA1 area.(2) GSK-3β: There was no visible difference among the total amountsof GSK-3βin each group(P＞0.05). But amounts of GSK-3βtransferred tonucleus from cytoplasm in IR and Li groups.(3)P-GSK-3β(Ser9): P-GSK-3β(Ser9) increased significantly afterreperfusion (Compared with SH groups, P＜0.01). Having been treated withlithium chloride, P-GSK-3β(Ser9) increased even higher(Compared with IRgroups, P＜0.01).Also, dosage dependence increase of P-GSK-3β(Ser9) bylithium chloride could be seen Clearly.Conclusion: Neuronal apoptosis and the transfer of GSK-3βcan beseen in happocampal CA1 areas fter MCAO/reperfusion in rats. Lithiumchloride can dose dependently suppress neuronal apoptosis and GSK-3β after MCAO/ reperfusion in rats. The neuroprotective effect of lithiumchloride might be correlated with its inhibition of GSK-3β.
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