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Temporal pattern of circulating leptin levels and obesity in congenic mice carrying an obesity quantitative trait locus, tabw2
Author(s) -
Kim Jung Han,
Stewart Taryn
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.750.5
Subject(s) - leptin , endocrinology , medicine , congenic , obesity , biology , circadian rhythm , gene , biochemistry
Previously, we established a congenic mouse strain that carries an obesity quantitative trait locus, tabw2 , derived from TALLYHO/Jng (TH) on a C57BL/6 (B6) background. B6.TH‐ tabw2 congenic mice have a significantly larger fat mass than controls, which is exaggerated with high‐fat high‐sucrose (HFS) diets. Leptin is produced in adipocytes and the circulating leptin levels are positively correlated with fat mass. Under normal homeostasis conditions, leptin is secreted in a diurnal rhythm. Interestingly, this diurnal rhythm of circulating leptin levels is dampened in obese subjects. The objective of this study was to investigate the diurnal rhythm of circulating leptin levels in tabw2 mice. Control and tabw2 mice were fed either chow or HFS diets beginning at 4 weeks of age for 10 weeks. Mice were bled at 6 AM, 12 PM, 6 PM, and 12 AM, and the plasma leptin concentrations determined using ELISA. On chow, the 24‐hour profile of circulating plasma levels of leptin was comparable between tabw2 and control mice. However, the average of the 24‐hour leptin concentrations, as expressed as the area under the curve, was significantly increased in tabw2 mice compared to controls (62±8 vs. 36±4, P <0.05). On HFS diets, the average of the 24‐hour leptin concentrations was increased in both tabw2 and control mice than on chow. However, the 24‐hour pattern was altered in tabw2 mice from controls; control mice showed the highest magnitude of the leptin increase from 6 PM to 12 AM, whereas tabw2 mice showed it from 12 PM to 6 PM. In conclusion, it appears that body fat mass above a certain threshold causes an altered diurnal pattern in circulating leptin levels, accelerating progression of the obesity in tabw2 congenic mice on HFS diets.