Nucleus Accumbens and Prefrontal Cortex Dopamine modifications during operant responding for sucrose

BASSAREO, VALENTINA;Musio P;CUCCA, FLAVIA;Di Chiara G.

2011-01-01

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Abstract

Mesolimbic dopamine (DA) plays a key role in the responsiveness to rewarding properties of natural and pharmacological stimuli. These stimuli are able to give rise to motivated behavior, and it is well known that conditioned stimuli (CS), linked with rewards (food, sex, drugs of abuse) (US), are essential to support it. The purpose of this investigation was to clarify the role of mesolimbic and mesocortical DA in the responsiveness to food and food-CS using an instrumental conditioning paradigm with fixed-ratio (FR) 1 (1 nose poke corresponds to 1 sucrose pellet) or 5 (5 nose pokes correspond to 1 sucrose pellet). We have coupled a self administration paradigm with microdialysis technique to study DA transmission in the NAc shell and core and in the prefrontal cortex during: 1) sucrose pellets seeking behavior, 2) extinction phase and 3) non-contingent presentation of sucrose pellets. The main finding of our study was that NAc shell DA has been activated not only by the conditioned cues but also by food after the instrumental conditioning, and that when both stimuli are presented in the same moment the increase of DA is strengthened and prolonged. We can conclude that DA in the NAc shell plays an important role on the acquisition and expression of motivated behavior in food consumption.