title: Regulation of plasma leptin in mice: influence of age, high-fat diet, and fasting.
abstract: Mechanisms regulating circulating leptin are incompletely understood. We developed a radioimmunoassay for mouse leptin to examine the influence of age, dietary fat content, and fasting on plasma concentrations of leptin in the background strain for the ob/ob mouse, the C57BL/6J mouse. Plasma leptin increased with age [5.3 +/- 0.6 ng/ml at 2 mo (n = 23) vs. 14.2 +/- 1.6 ng/ml at 11 mo (n = 15), P < 0.001]. Across all age groups (2-11 mo, n = 160), log plasma leptin correlated with body weight (r = 0.68, P < 0.0001), plasma insulin (r = 0.38, P < 0.001), and amount of intra-abdominal fat (r = 0.90, P < 0.001), as revealed by magnetic resonance imaging. Plasma leptin was increased by a high-fat diet (58% fat for 10 mo) and reduced by fasting for 48 h. The reduction of plasma leptin was correlated with the reduction of plasma insulin (r = 0.43, P = 0.012) but not with the initial body weight or the change in body weight. Moreover, the reduction in plasma leptin by fasting was impaired by high-fat diet. Thus plasma leptin in C57BL/6J mice 1) increases with age or a high-fat diet; 2) correlates with body weight, fat content, and plasma insulin; and 3) is reduced during fasting by an action inhibited by high-fat diet and related to changes of plasma insulin.
authors.affiliation: Department of Medicine, Lund University, Malmö, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Ahrén
authors.forename: S
authors.initials: S
authors.lastname: Månsson
authors.forename: R L
authors.initials: RL
authors.lastname: Gingerich
authors.forename: P J
authors.initials: PJ
authors.lastname: Havel
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology / Q000254:growth & development; D000375:Aging / Q000097:blood*; D000818:Animals; D001835:Body Weight; D004041:Dietary Fats; D005215:Fasting; D005260:Female; D007328:Insulin / Q000097:blood; D020738:Leptin; D008279:Magnetic Resonance Imaging; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009765:Obesity / Q000097:blood* / Q000503:physiopathology; D011506:Proteins / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods; D015203:Reproducibility of Results
chemical_list: D004041:Dietary Fats; D007328:Insulin; D020738:Leptin; D011506:Proteins