Cocaine Enhances the Changes in Extracellular Dopamine in Nucleus Accumbens Associated with Reinforcing Stimuli: A High-speed Chronoamperometric Study in Freely Moving Rats

Authors

  • Eugene A. Kiyatkin

    Corresponding author
    1. Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Quebec H3H 1K5, Canada, and Douglas Hospital Research Center, McGill University, Verdun, Quebec H4H 1R3, Canada
      Eugene A. Kiyatkin, Department of Psychiatry, Medical College of Wisconsin, 8701 Watertown Plank Road, MFRC-4029, WI 53226, USA
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      Department of Psychiatry, Medical College of Wisconsin, 8701 Watertown Plank Road, MFRC-4029, WI 53226, USA


Eugene A. Kiyatkin, Department of Psychiatry, Medical College of Wisconsin, 8701 Watertown Plank Road, MFRC-4029, WI 53226, USA

Abstract

Numerous data suggest that the mesocorticolimbic dopamine (DA) system is critically involved in the organization and regulation of goal-directed behaviours of various types as well as in the mediation of the psychogenic effects of cocaine. To test the hypothesis that cocaine not only alters levels of extracellular DA within the mesolimbic DA system, but in addition changes the response of this system to reinforcing environmental stimuli, a study using high-speed chronoamperometry was done to evaluate the effects of cocaine (15 mg/kg, i.p.) on extracellular DA in the nucleus accumbens and to assess the effects of cocaine on the response evoked by the presentation of tail-pinch and palatable food. Cocaine was found to induce long-term biphasic changes in extracellular DA (an increase followed by a decrease) and, more importantly, to enhance DA increases evoked by both tail-pinch and food. The powerful enhancing action of cocaine on DA release, triggered by significant environmental stimuli and associated with behaviours of different types, is considered to be a possible primary mechanism of its rewarding or euphorigenic effect.

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