ABSTRACT
AIM:To observe the effect of acupuncture on adenosine A1 receptor(A1R)in the caudate puta-men(CPu)of complete Freund's adjuvant(CFA)rats,and to explore the potential mechanism of acupuncture in treat-ment of inflammatory pain.METHODS:Sixty-four 6～8-week-old male Wistar rats were randomly divided into saline group,model group(CFA group),CFA+manual acupuncture(MA)group,CFA+solvent dimethyl sulfoxide(DMSO)group,CFA+A1R agonist 2-chloro-N6-cyclopentyladenosine(CCPA)group,CFA+A1R antagonist 8-cyclopentyl-1,3-di-propylxanthine(DPCPX)group,CFA+MA+DMSO group and CFA+MA+DPCPX group.In MA groups,on the 2nd day af-ter modeling,the rats were needled at Zusanli points on both sides,30 min at a time,once per day,for 7 d.Pain threshold of plantar thermal radiation was used to observe the pain response of the rats.The content of cyclic adenosine monophos-phate(cAMP)in the CPu was detected by ELISA.The protein expression and phosphorylation levels of protein kinase A(PKA)and cAMP response element-binding protein(CREB)were detected by Western blot.The expression of A1R in the CPu was detected by immunofluorescence staining.RESULTS:Compared with saline group,CFA modeling signifi-cantly lowered the thermal pain threshold of the rats(P<0.01).Compared with CFA group,the thermal pain threshold of the rats in CFA+MA group and CFA+CCPA group was significantly increased(P<0.05 or P<0.01).Compared with CFA+ MA+DMSO group,the thermal pain threshold of the rats in CFA+MA+DPCPX group was decreased(P<0.05).Compared with CFA group,A1R protein relative expression level and positive cells in the CPu of the rats in CFA+MA group were in-creased(P<0.05 or P<0.01).Compared with saline group,cAMP content and p-CREB protein level in the CPu of the rats in CFA+MA group were decreased(P<0.05).Compared with CFA+DMSO group,cAMP content and p-CREB pro-tein level in CFA+MA+DMSO and CFA+CCPA groups were significantly decreased(P<0.01).Compared with CFA+MA+ DMSO group,the levels of cAMP,p-PKA and p-CREB in CFA+MA+DPCPX group were significantly increased(P<0.05 or P<0.01).CONCLUSION:Acupuncture on bilateral Zusanli can relieve inflammatory pain in CFA rats,and its mech-anism may be related to A1R/cAMP/p-CREB signaling pathway.