title: Zinc deficiency changes preferred macronutrient intake in subpopulations of Sprague-Dawley outbred rats and reduces hepatic pyruvate kinase gene expression.
abstract: Macronutrient selection patterns of male rats were analyzed using a 3-choice macronutrient selection system providing either adequate (+Zn) or deficient (-Zn) levels of zinc (30 or 1 mg Zn/kg). In study 1, rats were provided +Zn and -Zn diets for 28 d. All rats preferred carbohydrate (>50% carbohydrate intake) at the onset, consuming an average of 71% carbohydrate (cho), 17% protein (pro), and 12% fat. By the end of the study, 25% of the -Zn rats switched preference from cho to fat, whereas no +Zn rats changed. In study 2, -Zn rats preferring fat increased their total intake to normal levels, but only 50% reverted to carbohydrate preference after 35 d of zinc repletion. Hypothalamic concentrations of galanin were measured in groups of +Zn and -Zn cho- and fat-preferring rats. Galanin, which may be regulated with fat intake, was not different in -Zn rats preferring fat vs. -Zn rats preferring cho. Galanin concentrations were higher in +Zn than in -Zn rats (P < 0.05) and higher in +Zn rats preferring fat than in +Zn rats preferring cho (P < 0.05). Hepatic pyruvate kinase (PK) mRNA concentrations were related to cho preference, regardless of zinc status. When PK mRNA levels were measured in rats consuming a single AIN- 93-based diet, PK mRNA levels were significantly reduced by zinc deficiency (P < 0.05). Because PK is highly regulated by insulin, the effect of insulin may be reduced by zinc deficiency, making it more difficult for -Zn rats to catabolize dietary cho. This may explain why some -Zn rats switched from preferring cho to fat after developing zinc deficiency.
authors.affiliation: Division of Nutritional Sciences and Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Kennedy
authors.forename: T M
authors.initials: TM
authors.lastname: Rains
authors.forename: N F
authors.initials: NF
authors.lastname: Shay
mesh_terms: D000818:Animals; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005518:Food Preferences; D019004:Galanin / Q000378:metabolism; D015870:Gene Expression; D007031:Hypothalamus / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D011770:Pyruvate Kinase / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015032:Zinc / Q000172:deficiency*
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D012333:RNA, Messenger; D019004:Galanin; D011770:Pyruvate Kinase; D015032:Zinc