鍼鎮痛の生理学的作用機序

抄録

Acupuncture therapy induces various physiological effects, and extensive basic research worldwide has been conducted to elucidate its mechanisms of action. Regarding its analgesic effects, activation of the descending pain inhibitory system, gate control, and promotion of secretion of pain–relieving substances such as endogenous opioids (e.g., β–endorphin and enkephalin) and gamma–aminobutyric acid (GABA) in the central nervous system have been demonstrated in basic research. However, recent reports have shown changes at the local sites (so–called acupuncture points) where acupuncture stimulation is applied, with mast cells being identified as key players. Mast cells are immune cells derived from bone marrow, containing chemical mediators such as histamine, leukotrienes, serotonin, and heparin in their granules. While not confirmed in all acupuncture points, areas traditionally used as acupuncture points have been found to harbor mast cells. Activation of mast cells by acupuncture stimulation is believed to lead to the secretion (degranulation) of these chemical mediators in trace amounts, resulting in various physiological activities including pain relief.

In addition to the above, we are investigating the effects of acupuncture stimulation on the secretion of orexin and oxytocin. Orexin and oxytocin are neuropeptides secreted from the hypothalamus, involved in the regulation of various physiological functions including pain control. Experiments using animal models of acute inflammatory pain have shown that acupuncture therapy enhances the secretion of orexin and oxytocin, suggesting their involvement in analgesia.

A characteristic of acupuncture therapy is its difference from pharmacotherapy in that it does not administer substances for treatment but rather harnesses the body's inherent healing capabilities. Furthermore, stimulation of the skin alone, as described above, elicits various simultaneous responses, and the combined effects of these responses contribute to the efficacy of acupuncture therapy.