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Behaviour, Appetite and Obesity
Abbreviations: DA, dopamine; DBH, dopamine [beta]-hydroxylase; FR, fixed ratio; NA, noradrenaline; PR, progressive ratio; RR, response requirement
Food craving, defined as intense desire or longing to eat a particular food(1), is a common experience for many individuals(2). Chocolate is the food most frequently craved, especially among women(3-5), and may become associated with unhealthy behaviours such as frequent snacking, binge eating and other eating disorders, which may lead to overweight, obesity and addiction-like behaviours(6).
The major problem in the treatment of excessive eating is the high rate of relapse to food seeking and maladaptive eating habits(7-9). Relapse to palatable foods, like that to drugs, is often induced by stress, cues previously associated with the reward and exposure to the drug or food previously sought(10-13).
Animal models indicate that the reinforcing and motivational effects of drugs and palatable foods are mediated by similar neuronal circuitries and molecular mechanisms(14-18). However, in contrast to the great deal of research focused on relapse to drug seeking(19-26), relatively fewer preclinical studies have been addressed to the identification of neuronal mechanisms of relapse to palatable food seeking(27-30). These studies adopted the same reinstatement models validated for drug relapse and applied eliciting stimuli, including cues previously associated with food, non-contingent exposure to food and physical or pharmacological stresses(31-33). These results indicate that the circuitries of reinstatement of food and drug seeking only partially overlap(31).
The aim of the present study was to investigate the effect of the selective dopamine (DA) [beta]-hydroxylase (DBH) inhibitor, nepicastat(34), on the reinforcing and motivational properties of a chocolate solution (powdered Nesquik®(Nestlé Italiana) diluted in water) and on relapse to chocolate seeking elicited by chocolate priming and by stimuli previously associated with reward availability and by chocolate priming. Nesquik®(Nestlé Italiana) solution has previously been validated in our laboratory for its highly...