Circulating triglycerides after a high-fat meal: predictor of increased caloric intake, orexigenic peptide expression, and dietary obesity.
Recent studies in normal-weight rats have linked circulating triglycerides (TG), when elevated by a high-fat (HF) compared to equicaloric low-fat (LF) meal, to an increase in subsequent food intake and hypothalamic expression of orexigenic peptides. The present study tested whether natural variations between rats in their TG levels after a small HF meal can also be related to their individual patterns of eating and peptide expression. In tail vein blood collected on three separate days 60 min after a HF meal, levels of TG were found to be strongly, positively correlated within rats from day to day but were highly variable between rats (75-365 mg/dl), allowing distinct subgroups (33% lowest or highest) to be formed. Compared to "Low-TG responders" with post-meal levels averaging 109 mg/dl, "High-TG responders" with 240 mg/dl showed in two separate experiments a significant increase in caloric intake in a subsequent laboratory chow meal. Before this larger meal, these rats with elevated TG consistently exhibited higher expression levels and synthesis of the orexigenic peptides, enkephalin, orexin and melanin-concentrating hormone, as revealed using real-time quantitative PCR, radiolabeled in situ hybridization, and immunofluorescence histochemistry. Over the long-term, the High-TG responders also showed an increased propensity to overeat, gain weight and accumulate excess body fat on a chronic HF diet. This simple measure of TG levels after a HF meal may offer a useful tool for identifying subpopulations with increased risk for overeating and dietary obesity and detecting early signs of brain disturbances that may contribute to this high-risk phenotype.
Karatayev
O
O
The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
Gaysinskaya
V
V
Chang
G-Q
GQ
Leibowitz
S F
SF
D000273:Adipose Tissue / Q000378:metabolism; D054369:Agouti-Related Protein / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000502:physiology; D004041:Dietary Fats / Q000008:administration & dosage / Q000097:blood; D004435:Eating / Q000502:physiology; D002149:Energy Intake / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology; D005455:Fluorescent Antibody Technique; D007028:Hypothalamic Hormones / Q000235:genetics / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D017403:In Situ Hybridization; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008297:Male; D008543:Melanins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D009765:Obesity / Q000378:metabolism*; D010907:Pituitary Hormones / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000097:blood*
D054369:Agouti-Related Protein; D004041:Dietary Fats; D007028:Hypothalamic Hormones; D007328:Insulin; D020738:Leptin; D008543:Melanins; D009479:Neuropeptides; D010907:Pituitary Hormones; D012333:RNA, Messenger; D014280:Triglycerides; C019463:melanin-concentrating hormone