Leptin action is modified by an interaction between dietary fat content and ambient temperature.
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 degrees 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 degrees 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 microg 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.
Department of Foods and Nutrition, University of Georgia, Athens, GA 30602, USA.
Andrea L
AL
Haltiner
Tiffany D
TD
Mitchell
Ruth B S
RB
Harris
D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology*; D002149:Energy Intake / Q000187:drug effects; D004777:Environment; D004822:Epididymis / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D020738:Leptin / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics; D054411:Receptors, Leptin; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D022722:Thermogenesis / Q000502:physiology
D004041:Dietary Fats; D020738:Leptin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; C515447:leptin receptor, mouse