Effects Of Lentivirus-mediated Down-regulation Of Nav 1.7 Expression By ShRNA On Pain Behavior In Chronic Inflammatory Pain Model Rats

Objective: To observe the effect of subarachnoid injection of Nav1.7 shRNA lentivirus vector on pain behavior in rats with chronic inflammatory pain,the expression of Nav1.7 in spinal dorsal root ganglion((Dorsal Root Ganglion,DRG)and the activation state of spinal cord astrocytes(GFAP expression).Methods: Eighteen healthy adult SD rats weighing 180 ml / 200 g were randomly divided into three groups: control group(Control group),chronic inflammatory pain group(CFA group)and lentivirus + chronic inflammatory pain group(LV+CFA group).The model of chronic inflammatory pain was established by subcutaneous injection of 0.1ml complete Freund’s adjuvant(Complete Freund’s Adjuvant,CFA into the sole of right hindfoot in Control group,and lentivirus vector 10 ul Nav1.7 shRNA was injected into subarachnoid space after subcutaneous injection of 0.1ml CFA in right hindfoot in LV+CFA group.The Mechanical Withdrawal Threshold(MWT)and the Paw Withdrawal Thermal Latency(PWTL)were measured before modeling and 1,3,5,7,9,11 and 13 days after modeling.On the 14 th day after modeling,all rats were killed for right L4-L6 DRG and lumbar enlargement of spinal cord.RT-PCR and Western-blot methods were used to detect the expression of Nav 1.7 of DRG and GFAP of lumbar enlargement of spinal cord.Results: Compared with Control group,mechanical foot withdrawal threshold decreased and heat tingling latency shortened at 13 days in CFA group.Nav 1.7 in DRG and GFAP in spinal cord enlargement were detected by RT-PCR and Western-blot(P < 0.05).Compared with CFA group,the threshold of mechanical foot withdrawal was increased and the latent period of heat tingling was prolonged 13 days after subarachnoid injection of Nav1.7 shRNA lentivirus vector inLV+CFA group.Nav1.7 in DRG was decreased by RT-PCR and Western-blot,and the expression of GFAP was not decreased in lumbar enlargement of spinal cord(P > 0.05).Conclusion: Subarachnoid injection of Nav1.7 shRNA lentivirus vector can effectively relieve chronic inflammatory pain induced by CFA and inhibit the expression of Nav1.7 of DRG in rats,but has no effect on the expression of GFAP in lumbar enlargement of spinal cord.