The pharmacology of flavor preferences conditioned by intragastric sucrose: Effects of opioid and dopamine receptor antagonism.
Item
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Title
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The pharmacology of flavor preferences conditioned by intragastric sucrose: Effects of opioid and dopamine receptor antagonism.
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Identifier
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AAI9986300
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identifier
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9986300
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Creator
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Azzara, Anthony Victor.
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Contributor
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Adviser: Anthony Sclafani
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Psychobiology | Psychology, Experimental | Psychology, Physiological
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Abstract
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Food preferences are influenced by learned associations between the food's flavor and postingestive nutritive effects. This dissertation research explored the neuropharmacology of conditioned flavor preferences (CFP). The role of the opioid system was determined using the general opioid antagonist naltrexone. Naltrexone administration did not block the expression of a preference for a flavor (CS+) paired with intragastric (IG) sucrose over another flavor (CS-) paired with IG water (Experiment 1). Additionally, naltrexone administered during training did not block the acquisition of a CS+ preference. Naltrexone-treated rats displayed preferences similar to controls, despite drinking less during training (Experiment 2). Experiment 3 revealed that naltrexone did not block the increased intake (acceptance) of the CS+, relative to the CS-, as measured in one-bottle tests. The role of the dopamine D2 receptor in CFP was investigated with the antagonist raclopride. Raclopride did not block the expression of an established CFP (Experiment 4). When given throughout training (Experiment 5), raclopride suppressed CS training intakes and CS+ preference in subsequent choice tests, relative to the control group. Experiment 6 added a yoked control group to control for the training intake reductions caused by raclopride. Raclopride treatment suppressed training intakes but did not block the acquisition of a preference, as the drug, control, and yoked control groups all preferred the CS+ to CS-. Experiment 7 examined the role of the D1 dopamine receptor in preference learning using the antagonist SCH23390. Unlike the control and yoked control groups, the SCH23390 treated rats failed to acquire a CS+ preference. Yet, SCH23390 treatment during two-bottle testing did not block the CS+ preference in the control or yoked groups, except at doses that greatly suppressed intake. Together, these results indicate that the opioid system is not critically involved in the acquisition or expression of a flavor preference conditioned by the postingestive actions of sucrose. D1, but not D2 dopamine receptors are important for the acquisition of a sucrose-conditioned flavor preference, but both receptor subtypes have a more limited role in preference expression. The differential involvement of opioid and dopamine receptors in flavor conditioning is consistent with recent neurochemical models of motivation.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
