Leptin action is modified by an interaction between dietary fat content and ambient temperature

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 287; no. 5; pp. R1250 - R1255
• Main Authors: Haltiner, Andrea L, Mitchell, Tiffany D, Harris, Ruth B. S
• Format: Journal Article
• Language: English
• Published: United States 01.11.2004
• Subjects: Adipose Tissue - metabolism; Animals; Body Composition - drug effects; Body Weight - drug effects; Body Weight - physiology; Diet; Dietary Fats - pharmacology; Energy Intake - drug effects; Environment; Epididymis - metabolism; Hypothalamus - metabolism; Leptin - pharmacology; Male; Mice; Mice, Inbred C57BL; Receptors, Cell Surface - biosynthesis; Receptors, Cell Surface - genetics; Receptors, Leptin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; Temperature; Thermogenesis - physiology
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00313.2004

Department of Foods and Nutrition and Department of Biology, University of Georgia, Athens, Georgia 30602 Submitted 12 May 2004 ; accepted in final form 19 July 2004 Mice adapted to a high-fat diet are reported to be leptin resistant; however, we previously reported that mice fed a high-fat (HF) diet and housed at 23°C remained sensitive to peripheral leptin and specifically lost body fat. This study tested whether leptin action was impaired by a combination of elevated environmental temperature and a HF diet. Male C57BL/6 mice were adapted to low-fat (LF) or HF diet from 10 days of age and were housed at 27°C from 28 days of age. From 35 days of age, baseline food intake and body weight were recorded for 1 wk and then mice on each diet were infused with 10 µg leptin/day or PBS from an intraperitoneal miniosmotic pump for 13 days. HF-fed mice had a higher energy intake than LF-fed mice and were heavier but not fatter. Serum leptin was lower in PBS-infused HF- than LF-fed mice. Leptin significantly inhibited energy intake of both LF-fed and HF-fed mice, and this was associated with a significant increase in hypothalamic long-form leptin receptors with no change in short-form leptin receptor or brown fat uncoupling protein-1 mRNA expression. Leptin significantly inhibited weight gain in both LF- and HF-fed mice but reduced the percentage of body fat mass only in LF-fed mice. The percentage of lean and fat tissue in HF-fed mice did not change, implying that overall growth had been inhibited. These results suggest that dietary fat modifies the mechanisms responsible for leptin-induced changes in body fat content and that those in HF-fed mice are sensitive to environmental temperature. mice; peripheral leptin; growth Address for reprint requests and other correspondence: R. B. S. Harris, Dept. of Foods and Nutrition, Dawson Hall, Univ. of Georgia, Athens, GA 30602 (E-mail: harrisrb{at}uga.edu )