Increased extracellular dopamine in the nucleus accumbens of the rat elicited by a conditional stimulus for food: an electrochemical study

Abstract

Stearate-modified graphite paste electrodes were implanted chronically into dopamine terminal regions in the nucleus accumbens or caudate nucleus of the rat. Reverse dialysis was used to demonstrate a selective response of these electrodes to dopamine, but not 3,4-dihydroxyphenylacetic acid or ascorbic acid. In a separate behavioural experiment, a significant increase in the chronoamperometric response was observed during presentation of a conditional stimulus predictive of food, and the electrochemical response remained elevated during and following consumption of the meal. Similar trends were observed from electrodes in the caudate nucleus. These data confirm the activation of mesolimbic dopamine neurons by incentive stimuli predictive of food and possibly by consumption of food. Together with other recent data on sex- and thirst-related increases in dopamine levels in the nucleus accumbens, these findings are consistent with a role for the nucleus accumbens as an interface between motivation and activation of the motor system.

Effects of Long-Term Acetyl-L-Carnitine Administration in Rats—II: Protection Against the Disrupting Effect of Stress on the Acquisition of Appetitive Behavior

“…Activation of the mesolimbic DA system, as quantified by electrophysiological, microdialysis, or voltammetric measures, can be triggered in animals by encounters with food, sex, drugs of abuse, and by secondary reinforcers of these incentives (Apicella et al, 1991;Blackburn et al, 1989;Fiorino et al, 1997;Kiyatkin and Gratton, 1994;Kiyatkin and Rebec, 1997;Kiyatkin and Stein, 1996;Mark et al, 1994;Mirenowicz and Schultz, 1996;Phillips et al, 1993;Schultz et al, 1992Schultz et al, , 1997. As each of these incentives can induce the acquisition of instrumental behaviors aimed at earning and/or consuming it, an increase in DA release in the NAcS has been associated with reward and reinforcement (Beninger and Miller, 1998;Hernandez and Hoebel, 1988;Kelley and Delfs, 1991;Kiyatkin, 1995;Nader et al, 1997;Robbins et al, 1989;Robbins and Everitt, 1996;Di Chiara, 1998).…”

Reward circuitry dysfunction in psychiatric and neurodevelopmental disorders and genetic syndromes: animal models and clinical findings

“…Mesolimboic DA release is associated with most pleasurable or rewarding events, and food is one type of reward that is often used during the training of animals. There is an increase in DA release (measured in awake, behaving animals by microdialysis or by fastscanning cyclic voltammetry) in the NAc in response to unexpected food rewards or stimuli that predict food rewards [72,308-310]. Moreover, drugs that enhance operant responding for such food rewards, such as amphetamine, are most effective when administered into the NAc, whereas DA receptor antagonists administered into the NAc block the stimulant effects [57,311].…”

Is there an evolutionary mismatch between the normal physiology of the human dopaminergic system and current environmental conditions in industrialized countries?

“…These dopaminergic systems are involved in those mechanisms which determine satiety to food, 23 sex, 24 and drugs of abuse. 25 In all these conditions, the most important dopamine systems involved are that of the terminal fields of the prefrontal cortex, 26 and that of the nucleus accumbens, 27 both originating from neurons located in the ventral tegmental area of the midbrain. Whether the stimulation of these neurons mediates the incentive salience (reviewed in Berridge and Robinson), 28 or the associative learning 29 capacities of an event, is still a matter of intense debate.…”