Plastic Change Of Axon Initial Segment Of Hippocampal CA3Neurons In Rat After Status Epilepticus Induced By Lithium And Pilocarpine

Object To investigate the expression of Nav1.6and ankyrin G which distribute in the axon initial segment(AIS) of hippocampal CA3neurons in rat after status epilepticus induced by lithium and pilocarpine, and explore their potential roles in epileptogenesis.Methods Sprague Dawley(SD) rats were divided randomly into experimental group and control group. The experimental group rats were induced status epilepticus(SE) with lithium chloride plus pilocarpine combinations by intraperitoneal injection, and were selected randomly for preparation of hippocampal frozen slices or extracting the proteins and mRNAs of hippocampal CA3neurons_in the time points of24hours,7days and60days after SE. Conversely, the control group rats were treated by a similar procedure with the experimental group rats but injected intraperitoneally with saline instead of lithium chloride and pilocarpine. Double immunofluorescence staining, Western blot and Real-Time PCR were performed to examine the expression of Navl.6and ankyrin G in the hippocampal CA3neurons of each group rats.Results The study of double immunofluorescence staining showed that Nav1.6and ankyrin G were co-located in the AIS of hippocampal CA3pyramidal neurons, and Nav1.6was distributed alone in the cytomembrane just with a lower density. Western blot and Real-Time PCR both showed that, compared with the control group, both the expression of Nav1.6protein and mRNA in24hours and60days after SE were significantly higher(P<0.01), the expression of ankyrin G with a molecular weight of480kDa or270kDa decreased in24hours(P<0.05) but increased in60days(P<0.05) after SE, the expression of ankyrin G mRNA in24hours and60days were significantly increased(P<0.01). However, the expression of both protein and mRNA of Nav1.6or ankyrin G in7days after SE was no significantly difference(P>0.05).Conclusions The expression of Nav1.6and ankyrin G in the AIS of hippocampal CA3pyramidal neurons increased in the lithium-pilocarpine model of epilepsy, which suggests plastic change of AIS and their potential roles in epileptogenesis.