Additive effects of chronic treatment with antidepressant drugs and intermittent treatment with a dopamine agonist.
Locomotor activity in response to the D2/D3 agonist quinpirole was studied in male rats treated chronically (25-40 days) with imipramine, amitriptyline or mianserin (5 mg/kg/day). All three antidepressants potentiated the response to quinpirole. Repeated administration of quinpirole at 3-day intervals also caused a marked increase in the locomotor response to quinpirole. Imipramine-treated animals were more active than vehicle-treated animals on all quinpirole trials. Animals tested in the locomotor activity apparatus for the first time following their fifth quinpirole injection showed sensitization, but to a lesser extent than animals tested repeatedly under quinpirole. This context-independent sensitization was potentiated by all three antidepressants. We discuss the potential clinical relevance of these results.
Department of Psychology, City of London Polytechnic, UK.
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M
Papp
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R
Muscat
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P
Willner
D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D004298:Dopamine / Q000502:physiology*; D015259:Dopamine Agents / Q000494:pharmacology*; D004357:Drug Synergism; D004873:Ergolines / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D019257:Quinpirole; D051381:Rats; D013268:Stimulation, Chemical
D000928:Antidepressive Agents; D015259:Dopamine Agents; D004873:Ergolines; D019257:Quinpirole; D004298:Dopamine