Activation Of P38MAPK Signaling Pathway In Rats Of Phantom Limb Pain

Objective:The purpose of this study was to investigate the role of p38 MAPK signaling pathway in the treatment of phantom limb pain in adult rats and to provide a new direction for the treatment of phantom limb pain.Methods:Healthy adult male Sprague-Dawley rats,weighing about 220-300 g,were selected.After a week of adaptive feeding,all animals were preoperatively prepared,fasting for 8 hours,free water,abdomen and right hind limb skin.After the operation was satisfied,48 healthy rats were randomly selected and anesthetized by intraperitoneal injection of 1%% pentobarbital,right hind limb sciatic nerve transection to establish phantom limb pain model.At the same time,the right hindlimb sciatic nerve was sutured layer by layer in the same anesthetic condition of the healthy rats in the same nest.This group was used as the sham operation group(S group,n=24).All rat operations are guaranteed to be performed within the same day.After operation,all animals waited for anesthesia to wake up naturally,and all animals were kept in cages under the same conditions.All animal wounds were disinfected on Day 2 after surgery to prevent wound infection from affecting the behavior of rats.At the same time,the behavior of self-biting toenail in rats was observed,and the degree of self-bite was evaluated according to the relevant literature according to the behavior of biting toenail.After the phantom limb pain rats model was successfully made,the rats with phantom limb pain after successful molding were randomly divided into 2 groups :the phantom limb pain group(P group,n=24)and the P38 MAPK pathway inhibitor group(P+I group,n=24).The rats in P+I group were injected with p38 MAPK inhibitor SB203580 0.8 mg / kg via caudal vein once a week after the model,and the rats in P I group were injected with p38 MAPK inhibitor SB203580 0.8 mg / kg,the other two groups were injected with 0.8 mg / kg saline via tail vein.Eight rats were randomly selected from each group at the end of the 4th week,the 6th weekend and the 8th weekend,respectively,Then the spinal cord tissues of the L3 and 5 segments and the dorsal root ganglion Dorsal Root Ganglion,DRGN were taken from the experimental rats,respectively.The phosphorylated p38 MAPKP p-p38 MAPK levels in both tissues were determined(The levels of P-p38 MAPK in spinal cord and dorsal root ganglion were detected by Western blot method and immunohistochemical method in each group).Results:Compared with sham operation group(S group),rats in phantom limb pain group(P group and P group I)had the behavior of biting toenail from the third day after operation,the highest bite score was 8 ~ 11 points.The inhibitor and saline were given after P+I rats biting score decreased.Compared with group S,the P-p38 MAPK level of P-p38 MAPK was significantly increased in both P and P + I groups(P < 0.05 or P < 0.01).Compared with P group,the expression of P-p38 MAPK in two parts of rats in P group was significantly lower than that in P group(P < 0.05 or P < 0.01).Conclusions:The p38 MAPK signaling pathway is involved in the regulation of phantom limb pain in rats.