Figure 2.

Retinol binding protein 4 and retinoids measured in the plasma and eyes of male mice fed a high fat diet. Controls were fed a standard diet. A and B, Rbp4 levels in C57BL/6J black mice fed an HFD from age 6 weeks to 6 months (m) and C57BL/6J^c2j albino mice fed an HFD from age 6 weeks to 12 months. Controls were fed a standard diet. Measurements were acquired by ELISA. Data are normalized as fold change in Rbp4 protein, HFD relative to standard diet level. Each sample value was calculated from duplicates. Individual values are plotted together with mean ± SD; n = 8. B, UPLC quantitation of plasma retinoids (all-trans-retinol atROL; all-trans-retinyl palmitate, atRE) in C57BL/6J mice fed an HFD for 3.5 months. Values per single eyes are plotted together with mean ± SD; n = 6. C, retinoid levels in the eyes of dark-adapted male black C57BL/6J mice fed an HFD for 3.5 months. Total retinoids (all-trans-retinol, all-trans-retinyl ester, all-trans-retinal, and 11-cis-retinal) were summed. Data are normalized as fold change in total ocular retinoids, HFD relative to standard diet (control). Values per single eye are plotted together with mean ± SD, n = 10. p values were determined by unpaired two-tailed t test. D, retinoid levels in the eyes of light-adapted black C57BL/6J mice fed an HFD for 4 months. Retinoids atROL, atRE, all-trans-retinal (atRAL), 11-cis-retinal (11cisRAL) are presented as picomoles per eye. Values per single eye are plotted together with mean ± SD; n = 6 to 14. E, retinoid levels in the eyes of albino C57BL/6J^c2j mice fed an HFD from age 6 weeks to 12 months. Retinoid extraction: method 1 (D and E). Values per single eye are plotted together with mean ± SD; n = 8. p values determined by two-way ANOVA and Sidak’s multiple comparison test (A, B, D, and E). HFD, high fat diet; UPLC, ultra-performance liquid chromatography.