Effect Of Caffeine On Acupuncture Analgesia In Chronic Constriction Injury Of The Partial Sciatic Nerve Model

Purpose:To investigate the effect of caffeine on acupuncture analgesia in rats with Chronic Constriction Injury of the Partial Sciatic Nerve Model.Method:Chronic constriction injury of the partial sciatic nerve(CCIp)models were evaluated via paw mechanical withdrawal latency(PMWL),paw mechanical withdrawal threshold(PMWT)and nociceptive reflex-induced electromyogram(C-fiber reflex EMG).Electric acupuncture(EA)was performed at GB30 to study its analgesic effects on neuropathic pain and its underlying mechanisms in rats.Result:Rats exhibited hindlimb dysfunction,hind paw shrinkage and lameness,and pain behaviors mirroring.The PMWL and PMWT was decreased significantly on day 5 after model as compared to one day before nerve ligation in water group and coffee group.The PMWL and PMWT was rised significantly after 2 weeks coffee intaked in coffee group.The latency of the pain threshold was significantly decreased in the model control group,and the latency of the rats in the water group was significantly higher than that in the coffee group.Pain threshold in the ear and body acupuncture treatment of was rised in water group,and there was no significant difference in coffee group.The C-fiber reflex-induced EMG of the biceps femoris was diminished in water group on the 5th day after nerve ligation,and increased after acupuncture treatment.The threshold of drinking coffee group did not change significantly in model and acupuncture intervention.EMG induced by the C-fiber reflex was significantly decreased at 0 to 3 min after EA at GB30 with four differents stimulation intensity in normal rats,whether or not to drink coffee.The time of EMG induced by the C-fiber reflex in coffee group was longer than in water group.Compared with the model control group,the effect of different intensity electroacupuncture was better and longer.Conclusion:Coffee intake can improve the rat's PMWT/PMWL,weaken the long-term acupuncture effect of ear or body acupuncture.There was no significant difference in the effect of electroacupuncture on the immediate acupuncture analgesic effect of EMG induced by the C-fiber reflex induced by nociceptive stimulation in coffee group and water group.Experimental results suggest that coffee can inhibit the acupuncture analgesic effect on chronic pain,but little effect on the immediate effect of acupuncture.