Role of protein kinase C in maintenance of chronic inflammatory pain in rats: the relationship with expression of Nav1.8 in dorsal root ganglion / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of protein kinase C in the maintenance of chronic inflammatory pain in rats and the relationship with the expression of Nav1.8 in the dorsal root ganglion (DRG).Methods Thirty pathogen-free healthy female Sprague-Dawley rats,weighing 180-220 g,were divided into 3 groups using a random number tablecontrol group (group C),chronic inflammatory pain group (group CIP) and PKC inhibitor group (group P).Normal saline 20 μl was injected into the plantar surface of the right hindpaw every day for 14 consecutive days in group C.Prostaglandin E2 100 ng was injected into the plantar surface of the right hindpaw every day for 13 consecutive days to establish the model of chronic inflammatory pain,and dimethyl sulfoxide 20μl was injected into the plantar surface of the right hindpaw on 14th day in group CIP.Prostaglandin E2 100 ng was injected into the plantar surface of the right hindpaw every day for 13 consecutive days,and PKC inhibitor GF1O9203X 100 nmol/20 μl was injected into the plantar surface of the right hindpaw on 14th day in group P.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before injection (T0) and 1,3,7 and 14 days after the last injection (T1-4).The DRGs of the lumbar segment (L4.5) were removed for determination of Nav1.8 expression using immunofluorescence and Western blot.Results Compared with group C,the MWT was significantly decreased at T1-4 in CIP and P groups,and the expression of Nav1.8 in DRGs was significantly up-regulated in group CIP (P＜0.05).Compared with group CIP,the MWT was significantly increased at T4,and the expression of Nav1.8 in DRGs was down-regulated in group P (P＜0.05).Conclusion Up-regulated expression of Nav1.8 after PKC activation in DRGs is involved in the maintenance of chronic inflammatory pain in rats.