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A DEMONSTRATION OF NALOXONE‐PRECIPITATED OPIATE WITHDRAWAL ON SINGLE NEURONES IN THE MORPHINE‐TOLERANT/DEPENDENT RAT BRAIN
Author(s) -
FRY J.P.,
HERZ A.,
ZIEGLGÄNSBERGER W.
Publication year - 1980
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.1476-5381.1980.tb14574.x
Subject(s) - (+) naloxone , excitatory postsynaptic potential , morphine , opiate , pharmacology , neuroscience , chemistry , acetylcholine , postsynaptic potential , endocrinology , medicine , opioid , psychology , inhibitory postsynaptic potential , receptor
1 A comparison has been made between the effects of microelectrophoretically applied naloxone on single neurones in the frontal cerebral cortex and the striatum of naive and of morphine‐tolerant/dependent rats, anaesthetized with a mixture of α‐chloralose and urethane. 2 Specificity of the results obtained was evaluated by contrasting the effects of alternate applications of the (+)‐ and (−)‐isomers of naloxone to the same neurones. 3 In naive rats naloxone had predominantly no effect, only a few cells revealing non‐specific depressant responses to the drug. 4 In morphine‐tolerant/dependent rats a higher proportion of neurones responded to naloxone; either with stereospecific excitatory responses, in which the activity evoked by l ‐glutamate or acetylcholine was increased, or with a non‐specific inhibition, similar to that observed in naive animals. 5 It is suggested that these excitatory responses to microelectrophoretically applied (−)‐naloxone represent opiate withdrawal responses at the single neurone level and that they reflect a latent hyperexcitability of the postsynaptic membrane in the morphine‐tolerant/dependent state.