Protective Effect Of Zinc Chelating Agent On Hippocampal Neurons And Its Learning And Memory In Epilepsy Mice

ObjectiveTo study the protective effect of zinc chelating agent,clioquinol,on the hippocampal neurons and its learning and memory function in pilocarpineinduced epilepsy mice.We use this experiment to analyze the function and mechanism of clioquinol in epilepsy,giving basic data for studying mechanism and treatment of epilepsy.MethodsPilocapine,300 mg/kg,was injected intraperitoneally to build up epilepsy mice model.Mice were divided into 3 groups.Mice in control group were injected with saline instead of pilocarpine or clioquinol.Mice in epilepsy group were injected with sailine 30 minutes after pilocarpine treatment.Mice in clioquinol group were treated with 15 mg/kg clioquinol 30 minutes after pilocarpine treatment.Then the seizure time and seizure level were observed from 30 minutes to 90 minutes after pilocarpine treatment.General ethology were observed everyday,including the mental condition,activity and appetite.Morris water maze detection was used to check both excape latency and time in correct quadrant during the following 6 days.Hippocampus were taken on 7th day.Autoradiography was used to check the distribution of zinc in hippocampus.Nissl staining was used to observe the morphology and number of hippocampal neurons in CA1 and CA3 area.Immunoblotting were used to check the expression of Bcl-2,Bax and caspase-3 protein in hippocampus.ResultsEthology observation showed that seizure appeared after pilocarpine treatment.The seizure level was more than grade III.Compared with control group,mice in epilepsy group showed higher seizure time and seizure level.Mice in clioquinol group showed lower seizure time and seizure level than those in epilepsy group(P<0.01).General ethology observation showed that the general condition in epilepsy group was bad and it was improved in clioquinol group.Morris water maze detection showed longer excape latency and shorter time in correct quadrant in epilepsy group,compared with control group.Clioquinol can cut down the excape latency time and increase the time in correct quadrant(P<0.01).Autoradiography showed increased zinc level in hippocampus of epilepsy group,compared with control group.Clioquinol reduced the zinc distribution in hippocampus(P<0.01).Nissl staining showed serious morphology changes in hippocampal neurons of epilepsy group which were improved in clioquinol group.Neuron counting revealed that the hippocampal neuron number in CA1 and CA3 area decreased significantly in epilepsy group.There were more neurons in clioquinol group than in epilepsy group(P<0.01).Immunoblotting displayed increased Bax and caspase-3 expression,decreased Bcl-2 expression and ratio of Bcl-2/Bax in epilepsy group.Compared with epilepsy group,clioquinol group displayed decreased Bax and caspase-3 expression,increased Bcl-2 expression and ratio of Bcl-2/Bax(P<0.01).ConclusionsZinc chelating agent,clioquinol,can reduce the distribution of zinc in the hippocampus of epilepsy mice,inhibit the injury and apoptosis of hippocampal neurons and improve the learning and memory function.Clioquinol have protective effect on the hippocampal neurons and learning and memory function in epilepsy mice.