ハリ麻酔の作用機序に関する薬理学的研究

Abstract

Since 1976, more than 50 successful cases of electroacupuncture (EAP) analgesia have been performed in the treatment of post-operative pain in tonsillectomized patients. This clinical experience prompted the author to conduct a series of experimental studies for clarifying the mechanisms underlying the EAP-analgesia.Besides the well-established roles of the endogenous opioidal system in EAP-analgesia, serotonergic and catecholaminergic systems have been implicated to be involved in the mechanism. In the present report, noradrenergic blockers were employed to see how EAP-analgesia was influenced by these drugs. Experiments were conducted on Wistar rats. In almost of all the cases, radiant heat noxious stimulations were applied on the tail, and bilateral tsu-san-li points were selected for EAP stimulation. Stimulation parameters were as follows: frequency, 4Hz; intensity, non-noxious but enough to produce muscle contraction; duration, 30min in almost all the cases; and pulse pattern, biphasic pulses generated by a Chinese EAP stimulator. Under these experimental conditions, apparent and durable analgesia was observed in 23/28 rats which lasted for over 4 hours after cessation of EAP-stimulation. The analgesia was antagonized by pre-treatments with α2-blockers, yohimbine and tolazoline, but not with α1-blockers, phenoxybenzamine or chlorpromazine. The production of analgesia during EAP was confirmed by monitoring multiple unitary activities of the parafascicular and centrum medium nuclei of the thalamus. The analgesia during EAP was also suppressed by tolazoline but not by chlorpromazine or phenoxybenzamine.From these data, the authors presents a hypothesis that the α2-adrenergic system may play an important role in the production or the regulation of EAP-analgesia.