title: Adaptation to a high-fat diet leads to hyperphagia and diminished sensitivity to cholecystokinin in rats.
abstract: Rats fed high-fat (HF) diets exhibit reduced sensitivity to some peptide satiety signals. We hypothesized that reduced sensitivity to satiety signals might contribute to overconsumption of a high-energy food after adaptation to HF diets. To test this, we measured daily, 3-h intake of a high-energy, high-fat (HHF, 22.3 kJ/g) test food in rats fed either low-fat (LF) or HF, isoenergetic (16.2 kJ/g) diets. During testing, half of each group received the HHF test food (LF/HHF; HF/HHF), whereas the other half received their respective maintenance diet (LF/LF; HF/HF). Rats fed a HF diet ate more of the HHF food during the 3-h testing period than LF-fed rats (HF/HHF = 7.7 +/- 0.3 g vs. LF/HHF = 5.5 +/- 0.2 g; P = 0.003). Rats tested on their own maintenance diets had similar intakes (HF/HF = 3.2 +/- 0.2 g vs. LF/LF = 3.7 +/- 0.3 g), which were lower (P < or = 0.008) than intakes of rats tested on HHF. HHF-tested rats did not differ in body weight by the end of wk 2 of testing. In a subsequent short-term choice preference test, rats exhibited an equal relative preference for HHF irrespective of their maintenance diets (HF = 63.1%, LF = 68.1%, P = 0.29). Finally, we examined the effect of intraperitoneal NaCl or cholecystokinin (CCK)-8 (100 and 250 ng/kg) injection on 1-h food intake. Both doses of CCK significantly suppressed food intake in LF-fed rats but not HF-fed rats. These results demonstrate that chronic ingestion of a HF diet leads to short-term overconsumption of a high-energy, high-fat food compared with LF-fed cohorts, which is associated with a decreased sensitivity to CCK.
authors.affiliation: Department of Nutritional Sciences, College of Health and Human Development, The Pennsylvania State University, University Park, 16802-6504, USA. dms493@psu.edu
authors.forename: David M
authors.initials: DM
authors.lastname: Savastano
authors.forename: Mihai
authors.initials: M
authors.lastname: Covasa
mesh_terms: D000064:Acclimatization; D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D018752:Diet, Fat-Restricted; D004041:Dietary Fats / Q000494:pharmacology; D002149:Energy Intake / Q000187:drug effects / Q000502:physiology; D006963:Hyperphagia / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004041:Dietary Fats; D002766:Cholecystokinin