It’s known that palatable food stimulates dopamine transmission preferentially in the nucleus accumbens shell and that this effect undergoes habituation after one trial. Drugs of abuse share with food the property of stimulating DA in the shell without undergoing on habituation. The lack of habituation in response to drugs of abuse is hypothesized to abnormally strengthen stimulus-drug association and result in the attribution of excessive motivational value to discrete stimuli or contexts predictive of drug availability. Our aim was to study the adaptive changes in the reactivity of DA transmission in the shell and core and prefrontal cortex of non deprived animals to highly palatable food after its long term consumption. The main finding of our study is that no habituation was observed in the response of shell DA to intraoral infusion of chocolate or corn oil in trained rats. No habituation was observed in the response of DA PFCX and a potentiation was observed in the NAc core. In control rats, trained to drink sugar solution or saline solution respectively intraoral chocolate infusion or corn oil infusion increase DA in the shell during the first day, but this stimulation underwent habituation during the 2nd and the 3rd infusion. In conclusion repeated exposure of the same palatable food abolishes the habituation of DA responsiveness in the NAc shell, and potentiates it in the NAc core. We can speculate that disturbances of feeding behavior are related to loss of adaptive regulation of food-stimulated release of DA in the NAc shell. Dopamine is repeatedly stimulate in the NAc shell as well as in the case of the drug of abuse administration.
Effect of chronic exposure in the mesolimbic and mesocortical dopamine response to palatable food
BASSAREO, VALENTINA;
2009-01-01
Abstract
It’s known that palatable food stimulates dopamine transmission preferentially in the nucleus accumbens shell and that this effect undergoes habituation after one trial. Drugs of abuse share with food the property of stimulating DA in the shell without undergoing on habituation. The lack of habituation in response to drugs of abuse is hypothesized to abnormally strengthen stimulus-drug association and result in the attribution of excessive motivational value to discrete stimuli or contexts predictive of drug availability. Our aim was to study the adaptive changes in the reactivity of DA transmission in the shell and core and prefrontal cortex of non deprived animals to highly palatable food after its long term consumption. The main finding of our study is that no habituation was observed in the response of shell DA to intraoral infusion of chocolate or corn oil in trained rats. No habituation was observed in the response of DA PFCX and a potentiation was observed in the NAc core. In control rats, trained to drink sugar solution or saline solution respectively intraoral chocolate infusion or corn oil infusion increase DA in the shell during the first day, but this stimulation underwent habituation during the 2nd and the 3rd infusion. In conclusion repeated exposure of the same palatable food abolishes the habituation of DA responsiveness in the NAc shell, and potentiates it in the NAc core. We can speculate that disturbances of feeding behavior are related to loss of adaptive regulation of food-stimulated release of DA in the NAc shell. Dopamine is repeatedly stimulate in the NAc shell as well as in the case of the drug of abuse administration.
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