Differential effects of the selective D2-antagonist raclopride in the nucleus accumbens of the rat on spontaneous and d-amphetamine-induced activity |
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Authors: | Ruud van den Boss Alexander R Cools Sven-Ove Ögren |
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Institution: | (1) Department of Psychoneuropharmacology, Astra Alab AB, S-151-85 Södertälje, Sweden;(2) Psychoneuropharmacological Research Unit, Catholic University of Nijmegen, P.O. Box 9101, NL-6500 HB Nijmegen, The Netherlands;(3) Present address: Psychoneuropharmacological Research Unit, Catholic University of Nijmegen, The Netherlands |
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Abstract: | The effect of the D2-antagonist raclopride was investigated in two test situations, which are presumed to involve dopamine (DA) transmission within the nucleus accumbens of the rat. Local injection of d-amphetamine sulphate (10 g/0.5 l) produced a marked increase in motor activity, measured as motility, locomotion, and rearing, which was dose- and time-dependently antagonised by local injection of raclopride (0.05–5.0 g/0.5 l). After an initial decrease, at low doses (0.05–0.25 g/0.5 l) an apparent enhancement of the d-amphetamine-induced motor activity appeared, which was most clearly seen with rearing. These lower doses, however, did not induce any clear changes in the exploratory activity in a novel environment (i.e., the second test situation). Only the higher doses used (1.0–5.0 g/0.5 l) decreased exploratory activity during the first 5–10 min, also measured as motility, locomotion, and rearing. These data are discussed with respect to the role of D2-receptors within the nucleus accumbens of rats in the motor activity induced by a novel environment and d-amphetamine. Overall, the data underline previous notions that raclopride is a potent antagonist of DA-mediated behaviour. |
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Keywords: | Nucleus accumbens d-Amphetamine activity Exploration Raclopride D2-receptors Schizophrenia Rat |
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