Anti-nociceptive effect of aspirin-pharmaceutical acupuncture in animal models

Although the oral administration of aspirin has an anti-nociceptive effect, the clinical use of aspirin is limited by its side effects and often by the patient’s conditions. Here, we investigate the anti-nociceptive effect of aspirin-pharmaceutical acupuncture (PA). Aspirin was subcutaneously injected into the ST36 acupoint (PA), and the effect of PA was compared with the effects of intraperitoneal (IP) and intramuscular (IM) injections. PA, IP, and IM significantly inhibited abdominal constrictions induced by acetic acid. PA (10 mg/kg) showed significant anti-nociceptive activity compared to IM. PA prolonged the latency period to 60 min in a tail-flick test (TFT) and showed attenuated sciatic nerve crash injury-induced hypersensitivity and the flinching responses in the late phase of the formalin test compared with the IP and IM. The anti-nociceptive effects by PA were reverted by naloxone administration and denervation. PA also decreased interleukin-6 and cyclooxygenase-2 expressions. The findings from this study will inform those who plan the aspirin therapies.