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Effect of etorphine, morphine and diprenorphine on neurones of the cerebral cortex and spinal cord of the rat
Author(s) -
BISCOE T. J.,
DUGGAN A. W.,
LODGE D.
Publication year - 1972
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1972.tb06865.x
Subject(s) - etorphine , diprenorphine , cerebral cortex , chemistry , spinal cord , neuroscience , morphine , anesthesia , opioid , medicine , psychology , opioid receptor , (+) naloxone , biochemistry , receptor
Summary1 . The actions of etorphine, morphine and diprenorphine were investigated on neurones of the cerebral cortex and spinal cord of rats anaesthetized with pentobarbitone. 2 . In the cerebral cortex, intravenous etorphine increased the latency of the primary evoked response to a peripheral nerve stimulus and suppressed the rhythmical after‐discharge. Diprenorphine reversed this effect. These actions were demonstrated on both field potentials and unit firing. 3 . Morphine had no effect on the primary response but the frequency of after‐discharge bursts was reduced and there was an increase in firing between bursts. 4 . In the cerebral cortex, electrophoretically applied etorphine reduced after‐discharges when applied for long periods but had no effect on the depressant actions of glycine and γ‐aminobutyric acid (GABA) nor on the excitant action of acetylcholine and l ‐glutamate. Similarly there was no alteration by etorphine of the effects of glycine, GABA and l ‐glutamate on spinal cord neurones. 5 . It is concluded that etorphine may act pre‐synaptically in the cerebral cortex.