Effects of morphine on gamma-aminobutyric acid turnover in the basal ganglia. Possible correlation with its biphasic action on motility.
Morphine (15 mg/kg i.p.) produces a biphasic action on motility: hypokinesia and muscular rigidity ("catatonia"), followed by a hyperkinesia in association with some stereotyped behaviour. In the present studies, alterations in GABA (gamma-aminobutyric acid) turnover were studied in possible correlation with changes in motility. As a criterion of GABA turnover its accumulation after inhibition of GABA transaminase by gamma-acetylene GABA (GAG) was measured. During the first, depressory phase only, GABA turnover was increased in the substantia nigra. In contrast, GABA turnover was continuously enhanced during both phases of morphine's action in the nucleus accumbens. No significant alterations were observed in striatum or globus pallidus. These findings seem to be consistent with the assumption of at least a short- and a long-lasting action of morphine on the basal ganglia.
Wenzel
J
J
Institut für Pharmakologie und Toxikologie, Philipps-Universität, Marburg/Lahn, Fed. Rep. of Germany.
Kuschinsky
K
K
D000480:Alkynes; D000614:Aminocaproates / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D000480:Alkynes; D000614:Aminocaproates; D005680:gamma-Aminobutyric Acid; C013785:4-amino-5-hexynoic acid; D009020:Morphine