Effect And Mechanism Of Caffeine On Acupuncture-Induced Analgesia In Neuropathic Pain

Objective:To explore the effects of caffeine administration in rats after partial sciatic nerve injury and the examining A1 receptors involonved mechanism of acupuncture analgesia.Methods:Using Dynamic Plantar Aesthesiometer to evaluate the paw latency and paw pressure of them. And they showing a decline on paw withdrawa latency and paw withdrawa pressure were randomly divided into control group, model group, model+ administration of caffeine group (model-caffeine group), model+EA group (model-EA group), model+administration of caffeine +EA group (model-caffeine-EA group). The female BALB/c rats were taken as animal model of neuropathic pain. The rats model of neuropathic pain were treated with electroacupuncture after oral administration of caffeine (70 mg/kg/d). Using electroacupuncture in the acupoint ST36 (Zusanli). Then the model-EA group and model-caffeine-EA group were given the electroacupuncture treatment on ST36 (Zusanli) which lasted for 10 courses with 6 days each course. After 5 courses, the model-EA group were administrated in caffeine and model-caffeine-EA group done administrated in caffeine.Then use Dynamic Plantar Aesthesiometer to analyze the paw withdrawa latency and paw withdrawa pressure in each group. The expression of AIR-mRNA in hypothalamus was detected.Results:1. The results of effect of Caffeine on the analgesic effect of electroacupunctureComparing with the control group,the paw withdrawa latency and paw withdrawa pressure of the model group was significantly reduced (P<0.05), the same change in the other groups (P<0.05);Compared with model group, the paw withdrawa latency and paw withdrawa pressure of model-EA group were obviously increased (P<0.05);Compared with model-EA group, the paw withdrawa latency and paw withdrawa pressure of model-caffeine-EA group were obviously increased (P<0.05);After 5 courses, the model-EA group were administrated in caffeine,compared with the first stage, the paw withdrawa latency and paw withdrawa pressure of the sixth course of the second phase significantly reduced (P<0.05);model-caffeine-EA group,compared with the first stage, the paw withdrawa latency and paw withdrawa pressure of the second phase were obviously increased (P<0.05).2. The results of effect of Caffeine on A1RmRNA expressionCompared with model group and model-caffeine-EA group, the expression of AlRmRNA in hypothalamus of model-EA group were increased;Compared with model group and model-caffeine group, the expression of the AlRmRNA in hypothalamus of model-caffeine-EA group were not significantly difference.Conclusions:These results-indicate that the use of caffeine can inhibit the analgesic effect of electroacupuncture;But stopping using of caffeine the inhibit the analgesic effect of electroacupuncture was eliminated;Through antagonism of Al receptors,caffeine inhibit the analgesic effect of electroacupuncture.