Effects Of Chronic Percutaneous Trigeminal Nerve Stimulation On The Hippocampal And Cortical Expression Of VGLUT1and VGAT In Chronic Epileptic Rats

ObjectiveThe effects of percutaneous trigeminal nerve chronic stimulation (TCNS) on theexpresssion of vesicular glutamate transporter1(VGLUT1) and vesicular GABAtransporter (VGAT) in the hippocampus and cortex were investigated in rats withpilocarpine-introduced chronic epilepsy to explore the possible anti-epilepticmechanisms of TNS.Material and Methods100rats, randomly selected from150healthy male ones, were injected with pilocarpineto create the chronic epilepsy models. Rats meeting the requirements of SE wererandomly divided into epilepsy (Pilo) group and percutaneous trigeminal nervestimulation (TNS) group. Control group, in which the rats treated with the same doseof normal saline instead of pilocarpine intraperitoneal injection, and pilo group wereboth treated with sham TNS for one month, and TNS group treated with TNS for onemonth. Rats in each group were sacrificed at24h、72h、7d、14d and28d post-TNSrespectively, and the brains were taken out for research. The expression of VGLUT1and VGAT in hippocampus and cortex was examined with double immunofluorescenceand western blot. All data was illustrated as Mean±SEM for each analyzed area. Allstatistical analyses were performed using non-parametric one-way (ANOVA) andTukey Honest post hoc comparisons. Probability values of <0.05were considered significant.Results1. The expression of VGLUT1in the hippocampus and cortexThe expression of VGLUT1in the hippocampus and cortex which reached peak at72hpost-TNS ascended before72h but descended later in Pilo, as well as in TNS grouprats. The expression of VGLUT1in Pilo and TNS group rats was significantlyincreased compared with the control group rats. The hippocampal and corticalexpression of VGLUT1was higher at24h post-TNS (p<0.01) but lower (p<0.01,p<0.05) at other different timepoints in TNS group rats than that in Pilo group rats.Successively at28d and14d post-TNS, no statistical difference was found inhippocampal and cortical expression of VGLUT1between TNS group and controlgroup (P>0.05), but the statistical difference between TNS group and Pilo group wasfound significant (P<0.05).2. The expression of VGAT in the hippocampus and cortexThe expression of VGAT in the hippocampus and cortex in both Pilo and TNS grouprats was significantly increased compared with that in the control group. Theexpression of VGAT in the hippocampus and cortex which reached peak at72hpost-TNS ascended before72h but descended later in Pilo, as well as in TNS grouprats. The hippocampal and cortical expression of VGAT was lower at72h post-TNS(p<0.01) but higher (p<0.01, p<0.05) at other different timepoints in TNS group ratsthan that in Pilo group rats. At28d post-TNS, no statistical difference was found inhippocampal and cortical expression of VGAT between pilo group and control group(P>0.05), but the statistical difference between TNS group and Pilo group was foundsignificant (P<0.05). ConclusionIn the processes of chronic epilepsy formation, i.e. epileptogenesis, induced byPilocarpine, percutaneous trigeminal nerve stimulation treatment may reduce brainexcitability, but enhance the endogenous inhibitory mechanism, thus reduce the excitedsusceptibility of cerebral. The mechanism may be related to the expression ofVGLUT1in the brain ascended first but descended later and the expression of VGATincreased. This may be one of TNS reduce the mechanism of seizures. TNS may exertits anti-epileptic function through regulating excitatory and inhibitory synaptictransmission in the cortex and hippocampus of epileptic brain.