Ontogeny of biphasic locomotor effects of quinpirole.
The effects of the dopamine D2/D3 receptor agonist quinpirole (LY171555) on locomotor activity were tested on rats of 10, 15, 20, 30, and 60 days of age. In two separate experiments, doses of 0 (vehicle), 0.02, 0.2, or 2.0 mg/kg quinpirole were injected SC into rats at each age, and their effects measured either for 2 h at 15-min intervals, or 30 min at 5-min intervals. At 10, 15, and 20 days of age, quinpirole significantly increased distance travelled in a dose-dependent manner. At 30 and 60 days of age, quinpirole significantly decreased distance travelled early in the session and increased it later. These results suggest that a dopamine autoreceptor begins to function between 20 and 30 days of age. Concomitant with the appearance of quinpirole-induced locomotor suppression early in the session, the amount of quinpirole-induced activation late in the session declined.
Van Hartesveldt
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Psychology Department, University of Florida, Gainesville 32611.
Meyer
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ME
Potter
T J
TJ
D000375:Aging / Q000523:psychology*; D000818:Animals; D018491:Dopamine Agonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004873:Ergolines / Q000494:pharmacology*; D005260:Female; D007279:Injections, Subcutaneous; D009043:Motor Activity / Q000187:drug effects*; D011247:Pregnancy; D019257:Quinpirole; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000819:agonists; D050637:Receptors, Dopamine D3
D018491:Dopamine Agonists; C493595:Drd3 protein, rat; D004873:Ergolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D019257:Quinpirole