UBC Theses and Dissertations
An in vivo electrochemical analysis of the role of dopamine in feeding behaviors Holmes, Lorinda Jean
The involvement of dopamine in anticipatory and consummatory aspects of feeding behaviors was investigated in the present thesis. All measurements of dopaminergic activity were taken by in vivo electrochemical techniques. In Experiment 1, dopamine efflux in the nucleus accumbens and caudate of male rats was monitored during sessions in which a small, unsignalled liquid meal was consumed. Increases in the electrochemical measure of dopamine activity, which were of similar temporal pattern and magnitude, were observed in both the nucleus accumbens and striatum following meal consumption. These data suggest a possible postingestional role of dopamine in these two brain structures. In Experiment 2, a conditioned feeding paradigm was utilized to study the role of dopamine during a discrete anticipatory phase of feeding. Rats were conditioned to discriminate between a positive conditioned stimulus (CS+) predictive of meal delivery, and a negative conditioned stimulus (CS-) that was not associated with food. Increases in dopamine activity, as determined by changes in electrochemical oxidation currents, were found to be greater during the CS+ than during the CS- in both the nucleus accumbens and caudate. In addition, the magnitude of increase was greater in the nucleus accumbens than the caudate, suggesting that the accumbens may be preferentially involved in the processing of external incentive stimuli. The results support a role for dopamine in both the nucleus accumbens and caudate during appetitive or anticipatory responding for food in the male rat.
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