Voltammetric evidence that subsensitivity to reward following chronic mild stress is associated with increased release of mesolimbic dopamine |
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Authors: | Jonathan A Stamford Richard Muscat John J O'Connor Jyoti Patel Stephen J Trout Walter J Wieczorek Zygmunt L Kruk Paul Willner |
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Institution: | (1) Department of Pharmacology, Queen Mary and Westfield College, University of London, Mile End Road, E1 4NS London, UK;(2) Department of Psychology, City of London Polytechnic, Old Castle Street, E1 7NT London, UK |
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Abstract: | Chronic exposure to mild unpredictable stress caused a decrease in rats' consumption of a palatable weak sucrose solution, which was reversed by chronic (5 weeks) administration of imipramine (5 mg/kg/day). Dopamine (DA) release in the nucleus accumbens (NAc) and caudate putamen (CPu) was measured in vivo using fast cyclic voltammetry, following electrical stimulation of the medial forebrain bundle. Experiments were performed under chloral hydrate anaesthesia 48 h after the termination of stress and the final imipramine injection. DA release was increased in the NAc of both stressed and imipramine-treated animals; imipramine did not normalize the increased DA release in stressed animals. In a further experiment, brain slices from stressed animals tended to be subsensitive to the inhibition of DA release in the NAc by quinpirole. No changes were observed in the CPu in any experiment. We discuss the relationship of these effects to stress-induced anhedonia. |
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Keywords: | Chronic mild stress Sucrose reward Voltammetry Dopamine release Autoreceptors Rat |
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