Dopamine depletion in nucleus accumbens influences locomotion but not force and timing of operant responding.
This experiment examined the role of dopamine (DA) in the nucleus accumbens in regulating beam pressing and locomotor responses. Six rats were rewarded with sucrose on a partial reinforcement schedule for pressing force-sensitive beams. Open-field locomotor activity, and the force and timing characteristics of operant motor responses were recorded. It is known that low doses of apomorphine decrease DA tone through activating DA autoreceptors, resulting in suppression of both operant responses and locomotion. Our results showed that DA depletion in the nucleus accumbens, induced by bilateral injection of 6-hydroxydopamine, did not affect the force and timing of operant responses: neither did it reverse the suppressive effects of low doses of apomorphine on the force and timing of operant responses. However, accumbens DA depletion did block the suppressive effect of apomorphine on open-field locomotion. These results were interpreted as support for the hypothesis that the suppressive effects of low doses of apomorphine on locomotion, but not on operant beam pressing, are mediated mainly by DA autoreceptors in the mesolimbic pathway.
Liu
X
X
Department of Psychology, State University of New York at Stony Brook, 11794-2500, USA.
Strecker
R E
RE
Brener
J
J
D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D016627:Oxidopamine; D051381:Rats
D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; D016627:Oxidopamine; D000661:Amphetamine; D001058:Apomorphine; D004298:Dopamine