Abstract
Two kinds of neuronal responses, excitation and inhibition evoked by strong electric shock stimulation of sural nerve, were recorded from the nucleus lateralis anterialis (n. LA) and sites nearby in the thalamus. Etorphine, when administrated iontophoretically, produced a naloxone-reversed depression on the response in all of the 45 excitatory units tested; whereas iontophoretic naloxone released 17 out of 19 inhibitory units from inhibition. Electroacupuncture depressed the excitatory response in 15 of 17 units tested; this acupunctural depression was reversed by iontophoretic naloxone in three out of five units. Electroacupuncture released from inhibition 7 of 8 units tested. The results indicate that the nociceptive responses in n. LA of the thalamus are possibly controlled by interactions of endorphins and opiate receptors and are both attenuated by electroacupuncture.
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