Trafficking of dietary fat in obesity-prone and obesity-resistant rats

• Published in: American journal of physiology: endocrinology and metabolism Vol. 291; no. 5; pp. E1083 - E1091
• Main Authors: Jackman, Matthew R, Kramer, Robert E, MacLean, Paul S, Bessesen, Daniel H
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.11.2006
• Subjects: Adipose Tissue - metabolism; Animals; Body Weight - physiology; Breeding; Carbon Dioxide - metabolism; Carbon Radioisotopes; Diet; Dietary Carbohydrates - pharmacokinetics; Dietary Fats - pharmacokinetics; Enteral Nutrition; Female; Intestinal Absorption; Lipoprotein Lipase - metabolism; Liver - metabolism; Male; Muscle, Skeletal - metabolism; Obesity; Obesity - genetics; Obesity - metabolism; Oils & fats; Oxidation; Oxidation-Reduction; Palmitates - pharmacokinetics; Phenotype; Rats; Rats, Sprague-Dawley; Sex Characteristics; Studies; Triglycerides - metabolism
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.00159.2006

1 Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado; 2 Department of Pediatrics, Division of Pediatric Gastroenterology and Nutrition, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida; and 3 Denver Health Medical Center, Aurora, Colorado Submitted 3 April 2006 ; accepted in final form 13 June 2006 The trafficking of dietary fat was assessed in obesity-prone (OP) and obesity-resistant (OR) male and female rats. Test meals containing [1- 14 C]palmitate were delivered through gastric feeding tubes while rats consumed a high-carbohydrate diet (HCD) or after 5 days of a high-fat diet (HFD). Over the subsequent 24 h, the appearance of 14 C was followed in the GI tract, skeletal muscles (SM), liver, adipose tissues (AT), and expired CO 2 . There was no difference in the production of 14 CO 2 between OP and OR rats consuming a HCD. However, after 5 days on HFD, OR rats produced significantly more 14 CO 2 after the test meal than OP rats ( P < 0.001 females, P = 0.03 males). The differential oxidation of dietary fat between OP and OR rats on HFD was not due to differences in absorption but rather was associated with preferential disposition of tracer to AT in OP rats. Measurements of lipoprotein lipase in part explained increased tracer uptake by AT in OP rats but were not consistent with increased SM tracer uptake in OR rats. Surprisingly, female rats oxidized more tracer than male rats irrespective of phenotype or diet. These results are consistent with the notion that differences in the partitioning of dietary fat between storage in AT and oxidation in SM and liver that develop shortly after the introduction of a HFD may in part underlie the differential tendency for OR and OP rats to gain weight on this diet. thinness; lipoprotein lipase; sex differences; dietary fat; high-fat diet Address for reprint requests and other correspondence: M. R. Jackman, Univ. of Colorado at Denver and Health Sciences Center, PO Box 6511, F-8305, Aurora, CO 80045 (e-mail: matthew.jackman{at}uchsc.edu )