Gabapentin Alleviates Neuropathic Pain By Increasing The Expression Of The Delta-Gabaa Receptor In The Spinal Cord

Objective To evaluate the effects of gabapentin on pain behavior and protein expression of spinal cordδ-GABA_Areceptor and PI3K/AKT signaling pathway in neuropathic pain(NP)rats,and to explore its analgesic mechanism.MethodsIn the first part,the effects of Gabapentin on pain behavior and expression ofδ-GABA_Areceptor protein in spinal cord of neuropathic pain(NP)rats were investigated.There were 24 male SD rats,6-7 weeks of age,weighing 225-275 g.In a random number table,we divided the rats into three groups(n=8):Sham group,CCI model group,Gabapentin+CCI model group(Gap group).A mouse model of neuropathic pain caused by chronic sciatic nerve compression injury(CCI)was established.On the 7th day after surgery,Sham group and CCI group were given the same amount of physiological saline into abdominal cavity.and Gap group was intraperitoneally injected with gabapentin 100mg/kg twice a day for 7 days.paw withdrwal threashold(PWT)and paw withdrwal latency(PWL)were measured 1 day before surgery and 3,7 and 14 days after surgery.The spinal cord of rats L4-6 was collected 14 days after surgery,and the protein expressions ofδ-GABAAR,AKT,p-AKT and PI3K were determined by Western blot.Theδ-GABAA receptor protein in spinal cord was identified by immunofluorescence technique in frozen section.Part Two:To investigate the role of spinal cord delta-GABAA receptor in relieving neuropathic pain with gabapentin.There were 24 male SD rats,6-7 weeks of age,weighing 225-275 g.In a random number table,we divided the rats into three groups(n=8):Gabapentin+CCI control group(NC),Gabapentin+CCI+delta-Gabaar interference virus group(Gap+sh RNA group),Gabapentin+CCI empty virus group(Gap+scr RNA group).Gap+sh RNA group and Gap+scr RNA group were injected with10μl corresponding virus,and NC group was injected with 10μl normal saline.Model was established 7 days later by chronic constriction injury(CCI).On the 7th day after surgery,Gabapentin was intraperitoneally injected 100mg/kg twice a day for 7 days.paw withdrwal threashold(PWT)and paw withdrwal latency(PWL)were measured 1day before surgery and 3,7 and 14 days after surgery,respectively.The spinal cord of rats L4-6 was collected 14 days after Model building,and the protein expressions ofδ-GABAAR,AKT,p-AKT and PI3K in the spinal cord were determined by Western blot.Results1.Gabapentin can relieve neuropathic pain in ratsCompared with Sham group,PWT in CCI group was decreased and PWL was shortened 3,7 and 14 days after surgery(P<0.05),the expression ofδ-GABAA receptor protein in the spinal cord of CCI rats was down-regulated,and the expression of PI3K and P-Akt/AKT were increased(p<0.05),and PWT in Gap group was decreased 3 and 7 days after surgery.PWL was shortened(P<0.05),and the expressions ofδ-GABAA receptor protein,PI3K and P-Akt/AKT were not statistically significant(p>0.05).Compared with CCI group,PWT was increased and PWL was prolonged in Gap group 14 days after surgery(P<0.05),theδ-GABAA receptor expression was up-regulated in Gap group,and the expressions of PI3K and P-Akt/AKT were decreased(p<0.05).The results indicated that Gabapentin alleviated neuropathic pain in rats by increasing the expression ofδ-GABAA receptor protein and inhibiting PI3K/AKT pathway.2.Effects of intrathecal injection of lentivirus interfering the expression ofδ-GABAAR protein on Gabapentin ratsIn order to further verify the role ofδ-GABAA receptor protein in gabapentin treatment of neuropathic pain,we studied the silencing ofδ-GABAA receptor protein by intracardial injection of lentivirus interfering withδ-GABAAR protein.The results showed that compared with Gap+scr RNA group,PWT was decreased and PWL was shortened in Gap+sh RNA group 14 days after surgery(P<0.05),theδ-GABAA receptor protein expression was down-regulated,and the expressions of PI3K and P-Akt/AKT were increased in the spinal cord of rats(P<0.05).There was no statistical significance between NC group and Gap+scr RNA group.Gap+sh RNA group reversed the therapeutic effect of gabapentin,suggesting that Gabapentin alleviates neuropathic pain by up-regulating the expression ofδ-GABAA receptor and inhibiting PI3K/AKT signaling pathway.3.δ-GABAAR was co-expressed with Neu N in spinal cordresults showed that theδ-GABAAR protein was co-expressed with the neuronal marker Neu N in the spinal cord of CCI rats,but not with GFAP(marker of astrocytes)and Iba-1(marker of microglia).Conclusion Gabapentin can relieve neuropathic pain by increasing the expression ofδ-GABAA receptor in spinal cord and inhibiting PI3K-AKT signaling pathway.