Abstract from study by Takahiro Takano at University of Rochester entitled Caffeine intake intervenes adenosine-mediated analgesic action of acupuncture
Acupuncture is a popular treatment for the wide spectrum of chronic pain but remains controversial due to our incomplete understanding of its biological basis. We previously showed in an animal model that the analgesic effect of acupuncture is mediated by the steep increase of extracellular purines and subsequent activation of adenosine A1 receptor at the acupuncture point. Such transient purine increases were also present with acupuncture in human. Since caffeine is a potent adenosine receptor antagonist and present in wide variety of foods and drinks, we here tested the effect of daily caffeine intake in the efficacy of the adenosine-mediated analgesia. Results: In the animal model of osteoarthritis pain, daily caffeine intake potently abolished the analgesic effect of acupuncture given at ST36 Zusanli, indicating that the caffeine that remain in the body effectively blocks adenosine receptor activation, which is required for pain suppression. Furthermore, the potency of suppression of pain depends on the concentration of the caffeine in drinking water. The action of caffeine was not due to its effect on central nervous system, since local administration of caffeine at the acupuncture point abolished the analgesic effect as well. Conclusions: our data indicate that caffeine consumption interferes with the outcome of acupuncture therapy. No clinical studies on acupuncture have taken caffeine intake into consideration. Caffeine intake may contribute to the contradictory data from the various clinical studies on the effect of acupuncture. Moreover, caffeine intake habits can be an important factor when potential chronic pain patients consider acupuncture therapy.