期刊
JOURNAL OF PSYCHOPHARMACOLOGY
卷 31, 期 11, 页码 1419-1429出版社
SAGE PUBLICATIONS LTD
DOI: 10.1177/0269881117735750
关键词
Cafeteria diet; delay discounting; diet-induced obesity; dopamine D-2 dysregulation; haloperidol; impulsivity
资金
- Idea Network for Biomedical Research Program, National Institute of Health [P20 GM103408]
- Idaho State University Psychology Department, College of Arts and Letters
- Office of Research
Diet-induced obesity is a laboratory procedure in which nonhuman animals are chronically exposed to a high-fat, high-sugar diet (i.e. cafeteria diet), which results in weight gain, altered sensitivity to reward, and alterations in the dopamine D-2 system. To date, few (if any) studies have examined age-related diet-induced obesity effects in a rat model or have used an impulsive choice task to characterize diet-induced behavioral alterations in reward processes. We exposed rats to a cafeteria-style diet for eight weeks starting at age 21 or 70 days. Following the diet exposures, the rats were tested on a delay discounting task - a measure of impulsive choice in which preference for smaller, immediate vs larger, delayed food reinforcers was assessed. Acute injections of haloperidol (0.03-0.3 mg/kg) were administered to assess the extent to which diet-induced changes in dopamine D-2 influence impulsive food choice. Across both age groups, rats fed a cafeteria diet gained the most weight and consumed more calories than rats fed a standard diet, with rats exposed during development showing the highest weight gain. No age- or diet-related baseline differences in delay discounting were revealed, however, haloperidol unmasked subtle diet-related differences by dose-dependently reducing choice for the larger, later reinforcer. Rats fed a cafeteria diet showed a leftward shift in the dose-response curve, suggesting heightened sensitivity to haloperidol, regardless of age, compared to rats fed a standard diet. Results indicate that chronic exposure to a cafeteria diet resulted in changes in underlying dopamine D-2 that manifested as greater impulsivity independent of age at diet exposure.
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