Abstract
Analgesia induced by acupuncture stimulation applied on around tsu-sanri point was measured by tail-flick latency of rats.
In acupuncture effective animals which showed a significant (p<0.05) increase of tailflick latency by acupuncture stimulation, intraperitoneally applied 1 mg/kg naloxone completely abolished acupuncture analgesia when it was applied on the well developed analgesia 30 minutes after on set of acupuncture stimulation. Such an antagonistic action of naloxone on acupuncture analgesia was dose-dependent. Tetrabenazine (25 mg/kg), a depletor of 5-hydroxytryptamine and catecholamines, also completely abolished acupuncture analgesia when it was applied on the well developed acupunctre analgesia, however its antagonistic action on acupuncture analgesia is more transient than that of naloxone, and last for 75minutes. This antagonistic action of tetrabenazine was also dose-dependent. Methysergide, an antagonist of 5-hydroxytryptamine, antagonized about 80% of acupuncture analgesia. This antagonistic action of methysergide was also dose-dependent.
These data indicate that acupuncture analgesia is induced by endogenous morphine like factors (MLF) which reveals its analgesic action by serotonergic and catecholaminergic systems.
