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Fig. 4
Figure 4.High-calorie diets caused proximal tubule enlargement and ectopic lipid accumulation. A and B: hematoxylin and eosin-stained sections from fish fed high-fat and high-calorie diets (high-fat, high-calorie, and high-calorie, high-fat diets) revealed pale cytoplasm with enlargement of the proximal tubule and proximal tubular lumen. The cross-sectional area of the proximal tubules in the high-fat and high-calorie diet-fed fish were significantly larger than those fed a control diet. C: fish fed either high-calorie diet developed ectopic lipid accumulation and brush border abnormalities. Representative electron micrographs of the apical membrane revealed a reduced and abnormal brush border (arrowheads) and copious lipid-containing vesicles (arrows). Scale bars = 25 µm in A and 1 µm in C. In B, at least 100 tubular cross-sections were measured from each group. Data are presented as means ± SD. Statistical tests were as follows: Welch ANOVA with Dunnett’s multiple comparisons test. **P < 0.01 and ****P < 0.0001. HC, high-calorie diet; HCHF, high-calorie, high-fat diet; HF, high-fat diet; ND, normal diet.