Caffeine Affects The Analgesic Effect Of Acupuncture On Inflammatory Pain

Aim:To reveal the influence of caffeine on acupuncture analgesia in inflammatory pain when intaking and stop intaking caffeine during electroacupuncture treatment.Methods:This study include two parts.The first part focused on the influence of acute caffeine intaking on acupuncture analgesia,the second part focused on the influence of caffeine stop intaking and continue intaking during treatment on acupuncture analgesia on the premise of have chronic caffeine intaking habit. In the first part, a total of 32 SD male rats were used, divided into blank group,model group, model-needle group and caffeine-needle group randomly. Inflammation pain model was established by injecting CFA, taking electroacupuncture as stimulating technique, selecting "Zusanli" at left-hind limb as pricking position.In addition,during the treatment,rats in caffeine-needle group intaked caffeine,rats in other groups intaked water.The thermal withdrawal latency was detected before model buildidng,after model building and 30 min after each acupuncture treatment.In the second part of the experiment,a total of 45 healthy male SD rats were used, randomly divided into blank group, model group, model-needle group,model-caffeine group and caffeine-needle group.Rats in the blank group intaked water for 4 weeks,rats in other groups intaked caffeine for 4 weeks.After 4 weeks’caffeine intaking,the model group began to receive CFA injection.Taking electroacupuncture 3 days after CFA injection.In addition,rats in model-caffeine group and caffeine-needle group continued intaking caffeine during electroacupuncture treatment,however,rats in model group and model-needle group intaked water instead of caffeine.The thermal withdrawal latency was detected during 4 weeks feeding,bofore model building,after model building and 30 min after each acupuncture treatment.Results:1. In the first part, after each treatment,the thermal withdrawal latency of rats in model-needle group is much higher than the model group(.P<0.01);there is no significant difference between the basic thermal withdrawal latency and the thermal withdrawal latency when 8 times treatments finished(P>0.05),after 9 times treatments, the thermal withdrawal latency increased from 7.03s±0.49 to 12.5s±0.89(P<0.01). While the thermal withdrawal latency of rats in coffee-needle group was not increased obviously, which was much lower than the model-needle group(P< 0.05),and there was no significant difference between the coffee-needle group and the model group(P> 0.05).In addition, the thermal withdrawal latency of rats in the coffee-needle group and model group didn’t recovered to the basic thermal withdrawal latency until 9 times treatments finished(P>0.05).2.In the second part,during 4 weeks’caffeine intaking,the thermal withdrawal latency didn’t change significantly in all groups.After each electroacupuncture,the thermal withdrawal latency of rats in the model-needle group increased significantly, wich was much higher than the model group(P<0.01),and there was no significant difference between the basic thermal withdrawal latency and the thermal withdrawal latency when 5 times treatments finished(P>0.05). After each treatment, the thermal withdrawal latency of caffeine-needle group wasn’t increased obviously,which was much lower than the model-needle group (P<0.05),and there was no difference between the model group(.P>0.05). In addition, rats in the model group, model-caffeine group and caffeine-needle group didn’t recovered to the basic thermal withdrawal latency until 7 times treatments finished(P>0.05).Conclusions:1.Caffeine can reduce the analgesic effect of acupuncture when intaking caffeine during acupuncture treatment;2.After 4 weeks caffeine intaking, continue intaking caffeine during acupuncture treatment can reduce the analgesic effect of acupuncture,while stop intaking caffeine during acupuncture treatment,the inhibition of caffeine on acupuncture analgesia was reversed.