title: Reduced sensitivity to cholecystokinin in male rats fed a high-fat diet is reversible.
abstract: Adult rats chronically fed a high-fat (HF) diet maintain reduced sensitivity to cholecystokinin (CCK). We hypothesized that, similar to adult rats, pups fed a HF diet would also exhibit reduced sensitivity to CCK. To test this, male pups fed low-fat (LF) and HF isoenergetic (16.2 kJ/g) diets were administered CCK intraperitoneally (0.125-1 microg/kg) 1 wk following dietary adaptation. After receiving 0.5 microg/kg CCK, pups fed the HF diet suppressed food intake less (8.9 +/- 5.0%) than pups fed the LF diet (28.9 +/- 4.7%; P < 0.05) relative to intakes after saline administration. We then assessed the development and extinction of changes in CCK sensitivity by switching the diets between the groups. The HF-fed group, when switched to the LF diet, regained sensitivity by wk 4 and suppressed food intake following administration of 0.25 microg/kg CCK (33.1 +/- 5.7%; P < 0.05). The LF-fed group, when switched to the HF diet, lost sensitivity by wk 2 and did not suppress food intake after administrations of CCK compared with saline. Finally, we examined if HF-fed rats have an increased sensitivity to corn oil during brief access tests using a multibottle gustometer. At oil concentrations of 25, 75, and 100%, rats fed the HF diet sampled more oil than LF-fed rats (P < 0.05). These findings demonstrate that male rat pups fed a HF diet exhibit reduced sensitivity to CCK, the development of this reduced sensitivity is quicker than its extinction, and rats consuming a HF diet have increased oral sensitivity to oils.
authors.affiliation: Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Swartz
authors.forename: David M
authors.initials: DM
authors.lastname: Savastano
authors.forename: Mihai
authors.initials: M
authors.lastname: Covasa
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002766:Cholecystokinin / Q000494:pharmacology*; D004041:Dietary Fats / Q000009:adverse effects*; D004435:Eating / Q000187:drug effects*; D002149:Energy Intake; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012528:Satiety Response / Q000187:drug effects
chemical_list: D004041:Dietary Fats; D002766:Cholecystokinin