Researching In Influence Of Nav1.8in Rat Dorsal Root Ganglia When Remifentanyl And Incisional Pain Induced Hyperalgesia

Objective：To abserve the influence of remifentanyl induced hyperalgesiain a rat model of incisional pain on the expression of Nav1.8in rat dorsal rootganglion (DRG), and to explore the impact of Nav1.8in hyperalgesia.Methods：Forty eight250~300g SD rats were randomly divided into6groups (n=8): physiological saline control group (N group), remifentanyl group(R group), incisional pain group (I group), remifentanyl and incision pain group(RI group), A-803467+incision pain group (JI group) and A803467+remifentanyl group (JR group). The rats in N, I group were injected with0.9%physiological saline1.0ml·kg-1·min-1for2h，I group incision pain surgery at thesame time.R and RI group were injected with remifentanyl1.0ml·kg-1·min-1for2h, RI group incision pain surgery at the same time. J and JR group,were injectedwith A-803467(20mg/kg), after10min,JR group injection with remifentanyl1.0ml·kg-1·min-1for2h. The response to thermal noxious stimulation wasmeasured and record at before and1/2h、1h、2h after the beginning of remifentanil infusion or saline and1/2h after the finishing of remifentanilinfusion or saline.The animals were sacrificed after thermal noxious stimulationwas measured.Their DRG of the spinal cord were removed．The mRNA andprotein expression of Nav1.8in spinal cord dorsal horn Was determined byRT-PCR and immunohistochemistry method.Results：Thermal noxious stimulation results: each group rats thermal painthreshold based value (T0), former drug (T1) thermal pain threshold is nostatistical significance (P>0.05). Compared with N group, at T2, T3, T4pointR、RI and JR group obviously higher (P <0.05)，at T5point, R、RI、I、JR andJI group reduced thermal pain threshold (P <0.05)；At T5point，JR groupreduced compared with R group, JR group increased compared with N group (P<0.05)；at T5point，JI group reduced compared with I group, JI group increasedcompared with N group (P <0.05). Results of RT-PCR and immunohistochemi-stry: compared with N group, R, I, and RI group Nav1.8mRNA and proteinexpression significantly increased, JR group and JI group expression decreasing(P <0.05); the level of increase in RI group is higher than in R group and Igroup (P <0.05).Conclusions： Nav1.8expression increased when Ramifentanyl andincisional pain induce hyperalgesia. Nav1.8in DRG is not the only relevantfactous on ramifentanyl and incisional pain induced hyperalgesia. Ramifentanylstill induce hyperalgesia through other channels.