Effects of P2X7 receptor inhibitor on kainic acid-induced epileptogenesis and hippocampal damage in mice
Objective To investigate the effects of P2X7 receptor(P2X7R)inhibitor on kainic acid-induced epilep-togenesis and hippocampal damage in mice.Methods Ninety-six male C57BL/6 mice were randomly divided into the control group of 36,the model group of 36,and the P2X7R inhibitor group of 24.Mice in the P2X7R inhibitor group were injected intraperitoneally with A438079,a P2X7R-specific inhibitor,30 min before modeling,and mice in the model and control groups were injected with the equal volume of normal saline at the same time point.The epilepsy model was estab-lished by intraperitoneal injection of kainic acid in the model group and the P2X7R inhibitor group,and an equal volume of normal saline was injected intraperitoneally in mice of the control group.The severity of seizures was assessed according to the electroencephalography(EEG).Western blotting was used to determine the level of hippocampal P2X7R expression,and Nissl staining was used to assess the extent of hippocampal damage in the CA1 region.Anxiety-like behaviors of mice in the control and model groups were observed in the open-field test.If anxiety-like behaviors existed in the model group,the model group was further divided into the anxiety control subgroup and P2X7R-inhibited subgroup;mice in the P2X7R-inhibited subgroup were injected with A438079 intraperitoneally every day,and mice in the anxiety control subgroup were injected with an equal volume of normal saline every day intraperitoneally,and open-field test was conducted again after 14 days.The morris water maze was used to observe the cognitive function of the mice,and if there was cognitive impairment in the model group,the model group was further divided into the cognitive control subgroup and P2X7R-inhibited sub-group.Mice in the P2X7R-inhibited subgroup were injected intraperitoneally with 15 mg/kg of A438079 every day,while mice in the cognitive control subgroup were injected with the equal volume of normal saline every day,and then the morris water maze was performed again after 14 days.Results The EEG did not show any epileptiform activity in the control group.Mice in the model group developed status epilepticus,in which EEG showed strong discharge power and high ampli-tude.Seizures occurred in the P2X7R inhibitor group,but the power and amplitude of EEG were attenuated compared with those in the model group;total power and mean amplitude were as follows:the model group>P2X7R inhibitor group>con-trol group(both P<0.05).The expression of P2X7R protein in the hippocampal tissues was higher than that in the control group,and the expression of P2X7R protein was lower in the P2X7R inhibitor group than in the model group(both P<0.05).The results of nissl staining showed that the structure of hippocampal CA1 region was intact,the number of surviv-ing neuronal cells was large,and the nissl body was big and its number was large in the control group;the structural integ-rity of hippocampal CA1 region was disrupted,the number of neuronal cells was small,and the number of nissl body de-creased in the model group;the structure of the hippocampal CA1 region,the number of neuronal cells,and the number of nissl body in the P2X7R inhibitor group improved in comparison with those in the model group.The results of the open-field test showed that the number of entering the central region and the length of stay in the central region were less in the model group than in the control group,and the number of entering the central region and the length of stay in the central re-gion were less in the anxiety control subgroup than in the P2X7R-inhibited subgroup(all P<0.05).The results of the mor-ris water maze showed that there were no statistically significant differences in the number of platform crossings or the length of stay in target quadrant between the model and control groups(all P>0.05).Conclusion P2X7R inhibitor re-duces the severity and frequency of kainic acid-induced seizures,ameliorates epilepsy-induced hippocampal damage,and alleviates anxiety-like behavior in epileptic mice.
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