Abstract
The intrinsic mechanism of the acupuncture needling effect on local muscle pain was investigated by experimental pain produced muscle after long tetanic stimulation of the guinea pig gastrocnemius muscle. Under 30 mg/kg pentobarbital anesthesia, the isometric ten-sion of both exposed gastrocnemius muscle were simultaneously recorded in situ. For producing experimental muscle stiffness and pain, 10 Hz tetanic stimulation was applied to the muscle for 40-60 minutes. Twitch height was used as an index of pain. A 0.25 mm needle was inserted straight into the perivertebral muscle. Knife cut of the brain was done by surgical knife. Potential evoked in the anterior hypothalamus by stimulation of the periver-tebral muscle was averaged 30 trials by a data analyser. The recovecy of reduced twitch hei-ght after tetanic stimulation was remarkably facilitated by needling of the ipsilateral periver-tebral muscle (L4-S1) ) . The effect was abolished by caudal knife cut of the anterior hypotha-lamus, but not by rostral or dorsal surface cut of the anterior hypothalamus. Electrical stimula-tion of the area above optic chiasma in the anterior hypothalamus facilitates the recovery of reduced twitch height of the contralateral gastrocnemius muscle after tetanic stimulation. Evo-ked potentials were recorded from stimulating electrode to produce facilitation of recovery upon stimulation of contralateral L5perivertebral muscle. Recovery from the reduction of twitch height of tetanized gastrocnemius muscle by needling of the perivertebral muscle might be caused by somat-autonomic reflex of which reflex center is in the contralateral anterior hypo-thalamus. Cholinergic nerves in sympathetic nerve might play a role to recover muscle circula-tion as efferent nerve.
