Chronic Excessive Fructose Intake Maximizes Brown Adipocyte Whitening but Causes Similar White Adipocyte Hypertrophy Than a High-Fat Diet in C57BL/6 Mice.

This study aimed to evaluate the differential role of a high-fat diet (HF) or high-fructose diet (HFRU) on white adipose tissue and brown adipose tissue remodeling in C57BL/6 mice. The animals were randomly assigned to receive HF (50% of energy as lipids), HFRU (50% of energy as fructose), or a control diet (C, 10% of energy as lipids) for 12 weeks. The HF group became overweight from the 7th week onwards, but both HF and HFRU groups showed hyperinsulinemia, oral glucose intolerance, and adverse adipose tissue remodeling. HF and HFRU groups showed interscapular brown adipose tissue whitening, tough the reduced Q [nuclei] suggested maximized brown adipocyte dysfunction due to the HFRU diet. In contrast, HF and HFRU diets exerted similar effects upon subcutaneous white adipocytes, with a similar average cross-sectional area. Immunohistochemistry confirmed the whitening enhancement with reduced UCP1 immunodensity in the HFRU group. In conclusion, HF and HFRU diets had indistinguishable effects upon white adipocyte morphology, but the HFRU diet provoked a more pronounced whitening than the HF diet after a 12-week protocol. These results point to the silent and harmful impact that excessive fructose has upon the metabolism of lean mice.