Scientific bases of acupuncture analgesia.

The present paper was to review the physiological bases of acupuncture analgesia (AA) on normal subjects, patients, and animals. Effect of acupuncture on pain perception in normal subjects was studied and compared with sham acupuncture. It was shown that the analgesic effect of acupuncture has its physiological basis. Using neurophysiological, neuropharmacological, neurobiochemical and neuromorphological methods, the neurohumoral mechanism of AA was studied from the peripheral neural pathway of acupuncture sensation (De-Qi sensation in Chinese traditional medicine) to the central neuromodulatory effect of AA. It was indicated that needling of acupuncture point could activate the afferent fibers of peripheral nerves to elicit De-Qi sensation, then ascended mainly through the ventro-lateral funiculi, which conducted pain and temperature sensation upward to the brain, activated the antinociceptive system including certain brain nuclei. modulators (opioid peptides), neurotransmitters, through the descending inhibitory pathway resulting in analgesia. Especially the clinical and laboratory results indicated that the endogenous opiate peptides (EOP) participated in AA from the presynaptic level to the receptor sites, which provided a scientific basis for understanding the mechanism of AA. Substantial evidences have been accumulated that acupuncture has prominent analgesic effect; but it fails to give sufficient analgesia during operation. Some effective measures to improve the therapeutic effect of acupuncture, such as the combination of acupuncture with drugs, the selection of suitable EA parameters and optimal time spacing should be adopted.