Aerobic Exercise Training May Not Offset the Pro-inflammatory Effects of a High Fat Feeding. Katie C. Carpenter, Lisa Esposito, Kelley A. Strohacker, Richard J. Simpson, Brian K. McFarlin. University of Houston, Houston, TX

Increased adiposity is associated with an increase in systemic inflammation, which is involved in the pathophysiology of various disease states. A current hypothesis in our laboratory suggests that the toll-like receptor 4 (TLR4) pathway may link physical activity and systemic inflammation. PURPOSE: The primary purpose was to determine if 6-weeks of aerobic exercise training (5 days per week, 1 hour per day. 21-22m/min) would limit the increase in systemic inflammation resulting from high-fat (60% of calories from fat) feeding. A secondary purpose was to determine if changes in cell-surface TLR4 expression would account for observed differences in inflammatory status between mice which exercise and those that remain sedentary. METHODS: 36 CD-1 male mice were randomly assigned to one of three groups (N=12/group): HF (remained sedentary and consumed a high-fat chow (60% fat)), HF-EX (consumed the high-fat chow and underwent an aerobic exercise intervention (running 4.56±0.08 h/week for 6 weeks, or LF (sedentary and consumed a low-fat chow (10% fat)). Key outcome measurements were made on weekly saphenous vein blood samples (~40 uL) using 3-color flow cytometry. Blood glucose and cholesterol concentration were analyzed by an enzymatic assay. RESULTS: Absolute and percent body weight gain over 6-weeks was similar between HF and HF-EX, but significantly greater than LF (P<0.001). HF and HF-EX had 66% more leukocytes than LF at weeks 3-5 (P<0.0001). HF and HF-EX had 145% greater CD11b+/14+/TLR4+ cells than LF (P=0.001). There was no difference in the concentration of CD11b+ cells expressing IL-6 or TNF-alpha following LPS-stimulation between HF and HF-EX. No significant difference was found for blood glucose and cholesterol concentrations between groups. CONCLUSIONS: Exercise training did not prevent weight gain during 6-weeks of high fat feeding. Since HF and HF+EX gained a similar amount of weight, they did not differ with regarding to blood monocytes expressing TLR4. Both HF and HF+EX were elevated above LF. More research is needed to determine how changes in the blood relate to changes in peripheral tissue compartments.



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