Role of spinal CX3CR1 in inflammatory pain in mice:the relationship with CaM-CaMKⅡ signaling pathways / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of spinal CX3C chemokine receptor 1 (CX3CR1) in inflammatory pain and the relationship with calmodulin (CaM)-calmodulin-dependent protein kinaseⅡ(CaMKⅡ) signaling pathways in mice.Methods Ninety-six pathogen-free healthy male C57BL6 mice,weighing 25-27 g,were divided into 3 groups using a random number tablecontrol group (group C,n=30),inflammatory pain group (group IP,n=36) and CX3CR1 antagonist group (group CA,n=30).Inflammatory pain was induced by injecting complete Freund′s adjuvant (CFA) 50 μl into the plantar surface of right hind paws in IP and CA groups,while the equal volume of normal saline was given instead in group C.In group CA,CX3CR1 antagonist (diluted to 1 μg/5 μl in phosphate buffer solution) was intrathecally injected at 1 h before CFA injection.The thermal paw withdrawal latency (TWL) was measured at 30 min before CFA injection (T0) and 30 min,1 h,2 h and 4 h after CFA injection (T2-4).The animals were then sacrificed,and the spinal cord was removed for determination of the expression of phosphorylated CaMKⅡ (p-CaMKⅡ),phosphorylated cyclic adenosine monophosphate response element-binding protein (p-CREB) and c-fos (by Western blot) and expression of CaMKⅡ,CREB and c-fos mRNA (using real-time polymerase chain reaction).Immunofluorescence was used to determine that p-CAMKⅡ was expressed in microglia.Results Compared with group C,the TWL was significantly shortened at T2-4,and the expression of p-CaMKⅡ,p-CREB and c-fos protein and mRNA was up-regulated at T1-4 in IP and CA groups (P<0.05).Compared with group IP,the TWL was significantly prolonged at T2-4,and the expression of p-CaMKⅡ,p-CREB and c-fos protein and mRNA was down-regulated at T1-4 in group CA (P<0.05).p-CaMKⅡ was co-expressed with the microglial specific biomarker.Conclusion CX3CR1 is involved in the development and maintenance of inflammatory pain through activating CaM-CaMKⅡsignaling pathways in mice.