•  
  •  
 

Abstract

Excess adiposity increases systemic inflammation, which is implicated in various diseases. Physical activity is a common treatment to reverse weight gain and increased disease risk; however, little evidence is available to determine if forced or voluntary exercise is more effective in mice. Such information has implications for the refinement of human exercise interventions. PURPOSE: To determine if 8-weeks of exercise combined with low-fat feeding reverses changes in disease risk, monocyte concentration and monocyte TLR2/TLR4 expression. METHODS: For 12-months, 24 CD-1 mice underwent pre-treatment, consuming either a low-fat (10% kcal from fat, N=6) or high-fat (60% kcal from fat, N=18) diet ad libitum. High-fat fed mice were randomly assigned to one of three groups (N=6/group): V-EX (low-fat chow, access to running wheel 5 d/week), F-EX (low-fat chow, forced treadmill running at 22 m/min, 60-min/d, 5 d/week), or SD (low-fat chow, no exercise). Mice pre-treated with low-fat chow served as controls (CN, N=6). Measurements were made on weekly saphenous vein blood samples using 3-color flow cytometry. Blood glucose and cholesterol concentration were analyzed weekly using a glucose and cholesterol analyzer. IPGTT was performed at baseline and week 8 and analyzed as area under the curve. RESULTS: All groups lost significant body weight over 8-weeks (P<0.001). V-EX ran 4.4x more than F-EX (P<0.001). There were no significant effects for blood cholesterol. CN had 26% higher glucose levels than V-EX (P=0.009). On average, there was a 59% decrease in IPGTT AUC from baseline to week 8 and V-EX decreased 37% more than CN. At week 8, monocyte concentration was 6x higher than week 1 (P=0.002). Specifically, V-EX was greater than both CN (49%) and F-EX (59%). Cell-surface TLR2 expression was significantly greater at week 6 (55%) and week 8 (23%) relative to baseline. Monocyte cell-surface TLR4 expression increased from baseline to week 8 (P<0.001). CONCLUSIONS: Combining low-fat diet and exercise caused significantly more weight loss than low-fat diet alone. Overall, there was decreased insulin resistance and decreased glucose, suggesting there may have been a decrease in type II diabetes risk. Lack of difference in monocyte concentration and TLR2/4 cell-surface expression suggest the diet and exercise intervention was not long enough to elicit changes in inflammation following the long-term high-fat feeding. More research is needed to understand the time course of these changes. This study was useful in understanding what occurs during a diet and exercise intervention and in directly comparing forced and voluntary exercise.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.