Opioids for hedonic experience and dopamine to get ready for it
Barbano MF, Cador M.
Laboratoire de Neuropsychobiologie des Désadaptations,
Centre National de la Recherche Scientifique,
Unité Mixte de Recherche 5541,
Université Victor Segalen Bordeaux 2,
146, rue Léo Saignat-BP 31, 33076,
Bordeaux Cedex, France.
Psychopharmacology (Berl). 2007 Apr;191(3):497-506.


BACKGROUND AND RATIONALE: More than two decades ago, Wise proposed his "anhedonia hypothesis" to explain the role of dopamine in motivated behaviors. The hypothesis posits that dopamine mediates the pleasure experienced by reward obtainment. However, some experimental findings have contested this hypothesis and several authors have proposed alternative functions for dopamine with regard to motivation. Brain dopamine has been suggested to rather code for the preparatory aspects of behavior, while brain opioids seem to mediate the perception of the hedonic properties of rewards. OBJECTIVES: The main goal of this review is to reexamine dopamine and opioids involvement in feeding when different aspects such as the anticipatory, motivational and consummatory components of this behavior are taken into account, but also when the physiologic state of the organism and the palatability of the food are considered. RESULTS AND CONCLUSIONS: Altogether, the data presented point out for an implication of dopamine in the anticipatory/preparatory aspects of feeding more than on the motivational and consummatory aspects. However, dopamine involvement in the anticipatory/preparatory component of feeding seems specifically related to very relevant stimuli, such as highly palatable foods. On the other hand, our data, as well as those present in the literature, strongly suggest a role for opioids in food intake through their modulation of the hedonic perception of food. As a consequence, opioids are involved in those aspects of motivation driven by food palatability rather than by food homeostatic need.
The pleasure seekers
The nucleus accumbens
The ventral pallidum and pleasure
Dopamine, pleasure and salience
Dopamine and dopaminergic antidepressants
Pain, motivation, pleasure and the rostral shell
Depression, dopamine and dextroamphetamine
Mesolimbic medium spiny neurons and pleasure
The magic millimeter? Locating the hedonic hotspot
Hedonic zonal shifts in the medial shell of the nucleus accumbens

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