Change in hippocampal voltage-gated Ⅰ sodium channel of Lithium chloride-Pilocarpine epileptic rat model / 中华实用儿科临床杂志

ABSTRACT

Objective To research the changes in hippocampal voltage-gated sodium channel of Lithium chloride-Pilocarpine epileptic rat models,including Ⅰ sodium channel α subunit protein (Nav1.1),mRNA of Ⅰ sodium channel alpha subunit protein gene and function of sodium channel.Methods Epileptic rat models of Lithium chloride-Pilocarpine were established.Nav1.1 expression in the hippocampus of experimental rats was detected by immunohistochemical staining method,and the changes in voltage-gated sodium channel function (the current-voltage curves,activation and inactivation curves and the recovery curve) of hippocampus nerve cells were detected by whole cell patch-clamp technique.Results (1) The Lithium chloride-Pilocarpine rat models were successfully reproduced.Three stages of behavior (acute,latent and chronic) of rat models were observed.The blank control group was free of seizure.(2) Immunohistochemistry results:neurons in CA1 and DG regions of hippocampal of epileptic rats were normal,and there was no obvious change in the expression of Nav1.1.In CA3 area,the degeneration and necrosis of neurons were obvious.Staining of Nav1.1 became superficial and even disappeared in these areas,but the normal tissues were enhanced around degenerative and necrotic neurons.Compared with the blank control group,the expression of Nav1.1 in the model group was higher(0.235 ±0.008 vs.O.210 ±0.002),and there was statistically significant difference (t'=-7.426,P ＜ 0.05).(3) The whole-cell patch-clamp technique showed that the sodium current density of the model group increased significantly compared with that of the blank group [(-319.70 ± 28.24) pA/pF vs.(-229.06 ± 26.01) pA/pF,t =8.178,P ＜ 0.05],the threshold value of activation curve decreased (4.15 ± 0.80 vs.4.50 ±0.85,t =11.020,P ＜ 0.05),the threshold value of inactivation curve increased (7.47 ± 0.53 vs.6.24 ±0.31,t =6.940,P ＜ 0.05),and the recovery time after inactivation shortened [(1.36 ± 0.15) ms vs.(1.86 ± 0.21)ms,t =6.712,P ＜ 0.05],and there were all statistically significant differences.Conclusion Repeated seizures can lead to increase Nav1.1 compensatory expression of,and significantly increase sodium channel current density,while the threshold value of activation curve decreases,the threshold value of inactivation curve rises,and the recovery time after inactivation is shortened,which eventually leads to increased neuron excitability and is more likely to cause seizures.