The Early Effects of High Fat Diet and Exercise on Markers of Adipose Tissue Inflammation in Mice

We have previously demonstrated that exercise training reduces the inflammatory profile in visceral adipose, yet this was observed in a state of existing obesity. It is important to understand the effects of exercise on adipose biology during developing obesity, in particular during initial exposure to a high fat (HF) diet, and how this impacts inflammation.
PURPOSE: To examine the effects of a 2 wk HF diet and exercise on inflammation in visceral adipose tissue in mice.
METHODS: C57BL/6 male mice (6 wks) were divided into 4 groups (n=8/grp): High fat/sedentary (HF/SED), HF/exercise (HF/EX), low fat /SED (LF/SED), and LF/EX. The HF and LF diets were 60 and 10% fat, respectively. Treadmill exercise was performed 12 m/min and 5% grade for 40 min/d for a total of 8 sessions. The diet and exercise interventions occurred concomitantly. Epididymal fat pads were excised and weighed at sacrifice. Glucose metabolism was assessed by intra-peritoneal glucose tolerance test (IPGTT). Plasma glucose and insulin levels were used for homeostatic model assessment of insulin resistance (HOMA-IR). Quantitative real-time PCR was performed to assess markers of macrophage content and inflammation in adipose. LF/EX group served as reference for relative mRNA calculations.

RESULTS: A diet effect was found for body weight (HF/SED: 23.5±0.6; HF/EX: 22. 2±0.6; LF/SED: 20.2±0.6; LF/EX: 20.0±0.5 g, p<0.05). IPGTT area under the curve was higher in the HF groups (p<0.05). No differences were found in HOMA-IR. Macrophage gene expression, F4/80 and CD11c, was not different between groups. Adipose inflammatory markers, monocyte chemoattractant protein-1 and tumor necrosis factor-α, were upregulated in the HF groups (3 fold and 2 fold change from LF, p<0.05, respectively). Anti-inflammatory marker, interleukin (IL)-10 was upregulated in the HF groups as well (1.7 fold change from LF, p<0.05). No exercise main effects or interactions effects were observed for any of these markers
CONCLUSIONS: While markers of macrophage infiltration were not evident, 2 wks of HF feeding induced upregulation of pro- and anti-inflammatory markers. Our low to moderate exercise stimulus does not appear to mitigate adipose inflammation early in the development of obesity.