Immunoblot analysis of tight junction (TJ) proteins in the total cell extracts of small intestinal mucosa of the OLETF and LETO rats fed the standard and high fat diets. The mucosa was collected at the end of the experiment (at 16 weeks) and immunoblotted for occludin, claudin-1, claudin-3, junctional adhesion molecules-1 (JAM-1), and β-actin. Specific bands of occludin (A), claudin-1 (B), claudin-3 (C), and JAM-1 (D) in the whole cell extracts were quantitated by densitometric analysis. The density values were normalized to the value obtained for the LETO rats fed the standard diet. Each value represents mean ± SEM, n = 9. Means without a common letter differ, P < 0.05. P values estimated by 2 way ANOVA were (A) 0.09 for strain, 0.09 for diet, and 0.62 for strain × diet, (B) 0.06 for strain, < 0.01 for diet, and 0.31 for strain × diet, (C) 0.01 for strain, 0.04 for diet, and 0.72 for strain × diet, and (D) <0.01 for strain, <0.01 for diet, and 0.18 for strain × diet.