PHARMACOLOGICAL CHARACTERIZATION OF SUBSTANCE-P-INDUCED NOCICEPTION IN MICE - MODULATION BY OPIOID AND NORADRENERGIC AGONISTS AT THE SPINAL LEVEL
- 1 January 1983
- journal article
- research article
- Vol. 226 (2), 398-404
Abstract
Mice were tested for antinociceptive activity after intrathecal injection of opioid or noradrenergic agonists by lumbar puncture. Opioid agonists with .mu.- or .delta.-activity and adrenergic agonists [including .beta.-funaltrexamine, clonidine, nalorphine, ethylketazocine, Met-enkephalin, [D-Ala2-Met5]enkephalin and [D-Ala2-D-Leu5]enkephalin] with .alpha.-activity demonstrated dose-related, receptor-mediated analgesia in the tail-flick assay, s.c. hypertonic saline assay and the intrathecal substance P behavioral assay. Inhibition of substance P-induced biting and scratching by intrathecally administered antinociceptive agents is likely mediated by post-synaptic receptors. This action of opioids and norepinephrine was antagonized by their respective pharmacological antagonists. Subanalgesic doses of Leu-enkephalin or norepinephrine potentiated the antinociceptive activity of morphine in the substance P assay. Opioid agonists potentiated the action of norepinephrine. Opioid and .alpha.-adrenergic agonists apparently act on separate receptors to produce a synergistic inhibition of the transmission of nociceptive information at the spinal level.This publication has 5 references indexed in Scilit:
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