Dopamine D1 and D2 antagonists block L-dopa-elicited air-stepping in neonatal rats.
When administered to rat pups that have been suspended in air, L-3,4-dihydroxyphenylalanine (L-DOPA) induces a highly stereotypic locomotor response referred to as air-stepping. In order to determine the respective roles of dopamine D1 and D2 receptors in the expression of air-stepping, the abilities of the selective D1 antagonist SCH 23390 and the selective D2 antagonist spiperone to block L-DOPA-induced air-stepping in 5-day-old rat pups were assessed. Both antagonists increased latency to onset, and both decreased total duration of air-stepping by decreasing the number and length of air-stepping episodes. Neither SCH 23390 nor spiperone altered the topography of the air-stepping response; however, subjects receiving lower doses of spiperone spent significantly more time with the body dorsiflexed and limbs extended (extension/tremor activity) than did control subjects. The results suggest that both the D1 and D2 receptor subtypes are involved in the production of L-DOPA-induced locomotor activity.
Sickles
A E
AE
Department of Psychology, University of Florida, Gainesville 32601.
Stehouwer
D J
DJ
Van Hartesveldt
C
C
D000818:Animals; D000831:Animals, Newborn / Q000523:psychology*; D001552:Benzazepines / Q000494:pharmacology; D018492:Dopamine Antagonists; D005260:Female; D007980:Levodopa / Q000037:antagonists & inhibitors*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D013134:Spiperone / Q000494:pharmacology; D013239:Stereotyped Behavior / Q000187:drug effects*; D013997:Time Factors
D001552:Benzazepines; D018492:Dopamine Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D007980:Levodopa; D013134:Spiperone