Rlationship between C-C chemokine receptor type 2 and p38 mitogen-activated protein kinase signaling pathway in the dorsal root ganglion of rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the relationship between C-C chemokinereceptor type 2 (CCR2) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathway in the dorsal root ganglion of rats and further clarify the mechanism of inflammatory pain.Methods Sevemy-two female Sprague-Dawley rats,weighing 150-180 g,aged 3-4 months,were randomly divided into 3 groups (n =24 each) using a random number table:control group (group C),inflammatory pain group (IP group) and CCR2 inhibitor RS102895 group (group RS).Inflammatory pain was induced by subcutaneous injection of Freund's adjuvant 100μl into the plantar surface of the right hindpaw.RS102895 20 mg/kg was injected subcutaneously once a day for 7 consecutive days in addition to Freund's adjuvant in group RS.Mechanical paw withdrawal threshold (MWT) was measured before injection and at 1,3,5 and 7 days after injection.At 3,5 and 7 days after injection,8 rats in each group were sacrificed and the dorsal root ganglions were removed for determination of the expression of CCR2 and phosphor-p38MAPK (p-p38MAPK) (by immuno-histochemical staining),and CCR2 and p38MAPK mRNA (using fluorescent quantitative PCR).Immuno-histochemical staining was scored.Results Compared with group C,MWT was significantly decreased after injection,the number of p-p38MAPK positive neurons and immuno-histochemical staining score were increased,and CCR2 and p38MAPK mRNA expression was up-regulated in IP and RS groups.Compared with group IP,MWT was significantly increased after injection,the number of p-p38MAPK positive neurons and immuno-histochemical staining score were decreased,and CCR2 and p3gMAPK mRNAexpression was down-regulated in RS group.Conclusion CCR2 in the dorsal root ganglion is involved in the development of inflammato pain possibility through activating p38MAPK signaling pathway in rats.