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- Title
Evidence for the sensitivity of operant timing behaviour to stimulation of D<sub>1</sub> dopamine receptors.
- Authors
Cheung, T. H. C.; Bezzina, G.; Hampson, C. L.; Body, S.; Fone, K. C. F.; Bradshaw, C. M.; Szabadi, E.
- Abstract
Temporal differentiation of operant behaviour is sensitive to dopaminergic manipulations. Previous studies using the fixed-interval peak procedure implicated D2-like dopamine receptors in these effects. However, recent findings suggest that d-amphetamine alters timing performance on the free-operant psychophysical procedure via D1-like receptors. It is not known whether this effect of d-amphetamine is mimicked by direct D1-like receptor stimulation. The effects of a D1-like receptor agonist 6-chloro-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzazepine (SKF-81297) on performance on the free-operant psychophysical procedure and the interaction between SKF-81297 and a D1-like receptor antagonist 8-bromo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol (SKF-83566) and a D2-like receptor antagonist haloperidol, were examined. Rats were trained to respond on two levers (A and B) under a free-operant psychophysical schedule, in which sucrose reinforcement was provided intermittently for responding on A during the first half and on B during the second half of 50-s trials. Logistic psychometric functions were fitted to the relative response rate data (percent responding on B [%B] vs time from trial onset [ t]) under each treatment condition, and quantitative indices of timing (T50 [value of t corresponding to %B = 50] and the Weber fraction [(T75-T25)/2T50; T25 and T75 are values of t corresponding to %B = 25 and %B = 75] were compared among treatments. SKF-81297 (0.8 mg kg−1) reduced T50; this effect was antagonized by SKF-83566 (0.03 mg kg−1) but not by haloperidol (0.05, 0.1 mg kg−1). Stimulation of D1-like dopamine receptors affects performance in the free-operant psychophysical procedure.
- Subjects
DOPAMINERGIC mechanisms; DOPAMINE receptors; CATECHOLAMINES; NEUROTRANSMITTER receptors; OPERANT behavior; PSYCHOMETRICS
- Publication
Psychopharmacology, 2007, Vol 195, Issue 2, p213
- ISSN
0033-3158
- Publication type
Article
- DOI
10.1007/s00213-007-0892-y