Figure 7

Effects of diet and strain on selected plasma adipokines and cytokines. Plasma samples were collected from tail blood at 45 days after rats were either placed on the high-fat diet or continued on the standard normal (low fat) chow. Samples were obtained before any pain models were implemented. Hatched bars indicate Long-Evans (LE) strain; open bars Sprague-Dawley (SD) strain. White bars indicate high-fat diet, gray bars indicate normal chow. Values shown are geometric means ± 95% confidence interval; statistical analysis was performed on log transformed data. High-fat diet increased plasma insulin (B) and leptin (C) only in the Long-Evans strain. Adiponectin levels were not significantly affected by strain or diet (A), but the ratio of leptin/adiponectin (L/A) was significantly elevated by high-fat diet only in Long-Evans rats (D). Plasma MCP did not differ between the groups (E). There was no effect of diet on plasma levels of IL-1β, but there was a significant effect of strain (F). *p < 0.05; **p < 0.01, significant difference between the indicated groups (two-way ANOVA with Bonferroni posttest comparing each group to the other 3 groups. The F values for the ANOVA analyses are shown in Supplemental Table 1. N = 8 male rats per group. At the time the sample was taken, the high-fat diet significantly increased weight in LE rats (438.5 ± 7.0 vs. 409.0 ± 8.3 grams, p < 0 0.05) but not in SD rats (357.5 ± 7.1 vs, 354.3 ± 11.9 grams) based on one-way ANOVA.