Bratcher, N. A., Farmer-Dougan, V., Dougan, J. D., Heidenreich, B. A., &
Garris, P. A. (2005).
The role of dopamine in reinforcement: Changes in reinforcement sensitivity
induced by D1-type, D2-type, and nonselective dopamine receptor agonists.
Journal of the Experimental Analysis of Behavior, 84, 371-
399.
Dose-dependent changes in sensitivity to reinforcement were found when rats were
treated with low, moderate, and high doses of the partial dopamine D1-type
receptor agonist SKF38393 and with the nonselective dopamine agonist
apomorphine, but did not change when rats were treated with similar doses of the
selective dopamine D2-type receptor agonist quinpirole. Estimates of bias did
not differ significantly across exposure to SKF38393 or quinpirole, but did
change significantly at the high dose of apomorphine. Estimates of goodness of
fit (r2) did not change significantly during quinpirole exposure. Poor goodness
of fit was obtained for the high doses of SKF38393 and apomorphine. Decrements
in absolute rates of responding were observed at the high dose of quinpirole and
at the moderate and high doses of SKF38393 and apomorphine. Changes in r2 and
absolute responding may be due to increases in stereotyped behavior during
SKF38393 and apomorphine exposure that, in contrast to quinpirole, were distant
from the response lever. The present data provide evidence that sensitivity to
reward is affected more strongly by dopamine D1-like receptors rather than D2-
like receptors, consistent with evidence from other studies investigating
consummatory dopamine behavior and the tonic/phasic dopamine hypothesis.
Key words: dopamine D1-like and D2–like receptors, quinpirole, SKF38393,
apomorphine, matching, sensitivity to reward, lever press, rat