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Increased or decreased locomotor response in rats following repeated administration of apomorphine depends on dosage interval

Increased or decreased locomotor response in rats following repeated administration of... 213 85 85 3 3 R. Castro P. Abreu C. H. Calzadilla M. Rodriguez Department of Physiology and Biochemistry, School of Medicine University of La Laguna Canary Islands Spain Abstract Administration of drugs that reduce the influence of dopamine at its receptor site can lead to postsynaptic supersensitivity, whereas treatment with dopamine (DA) agonists can cause postsynaptic subsensitivity. Both unaltered and enhanced postsynaptic responses to DA have been shown after pretreatment with DA agonists. In the present manuscript pretreatment with apomorphine, a dopaminergic agonist, is shown to induce either increased or reduced locomotor activity. When a drug-free period between successive injections was allowed, apomorphine induced an enhanced locomotor response, whereas a reduced response occurred when each dose was injected before the previous apomorphine dose had been completely metabolized. Pretreatment with both high (1 and 3 mg/kg) and low (0.05 mg/kg) apomorphine doses enhanced the response. Apomorphine treatment that caused enhanced locomotor responses did not modify the stereotypy response to the drug. Similar enhanced or reduced response were found in rats with partial lesions of the nigrostriatal system. These altered responses to DA agonists may have important clinical consequences. The present data also suggest the existence of a different DA systems for locomotor and stereotypy actions of dopaminergic agonists. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Psychopharmacology Springer Journals

Increased or decreased locomotor response in rats following repeated administration of apomorphine depends on dosage interval

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References (55)

Publisher
Springer Journals
Copyright
Copyright © 1985 by Springer-Verlag
Subject
Biomedicine; Pharmacology/Toxicology; Psychiatry
ISSN
0033-3158
eISSN
1432-2072
DOI
10.1007/BF00428198
Publisher site
See Article on Publisher Site

Abstract

213 85 85 3 3 R. Castro P. Abreu C. H. Calzadilla M. Rodriguez Department of Physiology and Biochemistry, School of Medicine University of La Laguna Canary Islands Spain Abstract Administration of drugs that reduce the influence of dopamine at its receptor site can lead to postsynaptic supersensitivity, whereas treatment with dopamine (DA) agonists can cause postsynaptic subsensitivity. Both unaltered and enhanced postsynaptic responses to DA have been shown after pretreatment with DA agonists. In the present manuscript pretreatment with apomorphine, a dopaminergic agonist, is shown to induce either increased or reduced locomotor activity. When a drug-free period between successive injections was allowed, apomorphine induced an enhanced locomotor response, whereas a reduced response occurred when each dose was injected before the previous apomorphine dose had been completely metabolized. Pretreatment with both high (1 and 3 mg/kg) and low (0.05 mg/kg) apomorphine doses enhanced the response. Apomorphine treatment that caused enhanced locomotor responses did not modify the stereotypy response to the drug. Similar enhanced or reduced response were found in rats with partial lesions of the nigrostriatal system. These altered responses to DA agonists may have important clinical consequences. The present data also suggest the existence of a different DA systems for locomotor and stereotypy actions of dopaminergic agonists.

Journal

PsychopharmacologySpringer Journals

Published: Mar 1, 1985

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