Opioids for hedonic experience and dopamine to get ready for it.
OBJECTIVE
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.


OBJECTIVE
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.


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.
Barbano
M Flavia
MF
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. flavia.barbano@upf.edu
Cador
Martine
M
D000818:Animals; D001921:Brain / Q000378:metabolism*; D003259:Consummatory Behavior; D004298:Dopamine / Q000378:metabolism*; D005247:Feeding Behavior; D005518:Food Preferences; D006706:Homeostasis; D006801:Humans; D009042:Motivation; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018847:Opioid Peptides / Q000378:metabolism*; D012201:Reward; D013649:Taste
D018377:Neurotransmitter Agents; D018847:Opioid Peptides; D004298:Dopamine