The effect of serotonin depletion on motor activity habituation, and [3H]muscimol binding in the rat hippocampus.
The effect of serotonin depletion (p-chlorophenylalanine pretreatment) on habituation of exploratory motor activity, and on cortical and hippocampal [3H]muscimol binding in vitro, was examined in rats. It appeared that the very strong decrease in serotonin concentration abolished motor habituation in the open field and decreased [3H]muscimol binding to cortical and hippocampal brain slices. The GABA(A) receptor down-regulation was due to a decrease in the apparent affinity of the radioligand for the receptors. p-Chlorophenylalanine-induced biochemical changes were selective and most probably secondary to serotonin depletion, as the serotonin synthesis inhibitor did not displace [3H]muscimol from its binding sites in neural membranes taken from the occipital cortex. It is concluded that there is a functional interaction between brain serotonin and GABA (gamma-aminobutyric acid) systems, both at behavioral and biochemical levels, that is involved in the motor activity habituation process.
Department of Biochemistry, Institute of Psychiatry and Neurology, Warsaw, Poland.
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Bidziński
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Siemiatkowski
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Członkowska
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Tonderska
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Płaźnik
D000818:Animals; D001667:Binding, Competitive; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000378:metabolism; D010134:Fenclonine / Q000494:pharmacology; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009118:Muscimol / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D018490:Serotonin Agents / Q000494:pharmacology; D014316:Tritium
D011963:Receptors, GABA-A; D018490:Serotonin Agents; D014316:Tritium; D009118:Muscimol; D012701:Serotonin; D010134:Fenclonine