The Effects Of Exercise On Markers Of Adipose Tissue Inflammation During Weight Cycling

The deleterious effects of weight cycling, characterized by successive cycles of weight-loss followed by weight-regain, remains poorly understood despite its common prevalence among overweight and obese adults. Central to the manifestation of obesity related comorbidities is the activation of proinflammatory pathways in adipose tissue. Exercise during weight-loss has shown to mitigate these pathways; however, it remains unclear if exercise can continue to provide protective effects during subsequent weight-regain. PURPOSE: To determine the effects of voluntary wheel running (VWR) on the mRNA expression of inflammatory markers in adipose tissue during weight cycling. METHODS: Male C57Bl/6 mice (n = 58) were randomly assigned to one of four groups for 28 weeks: 1) a low-fat diet control (LFD; 10% kcal from fat), 2) high-fat diet control (HFD; 60% kcal from fat), 3) alternating HFD (10 weeks)-LFD (8 weeks)-HFD (10 weeks) to simulate weight cycling (WC), or 4) a diet-matched WC group with VWR (WC + VWR). After 28 weeks, MCP-1, CD11c, CD163, F4/80 and TNFα mRNA levels were quantified in perigonadal adipose tissue by RT-qPCR. A one-way ANOVA was used to identify significant (p < 0.05) differences between groups. RESULTS: Following 28 weeks, WC + VWR mice were (p < 0.05) lighter than both HFD and WC mice, but HFD, WC and WC + VWR mice were heavier than LFD mice (Table 1). In adipose tissue, F4/80, CD11c and MCP-1 in HFD, WC and WC + VWR mice were (p < 0.05) greater than LFD. In contrast, CD163 was (p < 0.05) lower in HFD, WC and WC + VWR when compared to LFD. When compared to LFD, CD11c was (p < 0.05) elevated in HFD, WC and WC + VWR. When compared to HFD, both WC and WC + VWR showed (p < 0.05) lower CD11c and TNFα. CONCLUSIONS: Overall, weight-cycling did not result in greater adipose mRNA levels of proinflammatory markers than continued consumption of an HFD. The addition of exercise reduced the amount of weight-regain during weight-cycling, but did not affect the markers of adipose inflammation. Table 1. - Effects of VWR during weight-cycling on body mass and adipose inflammation. Variable LFD (n = 15) HFD (n = 15) WC (n = 16) WC + VWR (n = 12) Body mass (g) 29.5 ± 0.6a 53.9 ± 0.9b 52.3 ± 0.8b 46.4 ± 1.0c F4/80 mRNA 1.10 ± 0.15a 9.92 ± 1.27b 7.44 ± 1.59b 7.34 ± 1.45b CD11c mRNA 1.28 ± 0.23a 21.45 ± 1.60b 10.30 ± 0.86c 14.31 ± 1.90c CD163 mRNA 1.28 ± 0.19a 0.29 ± 0.04b 0.23 ± 0.03b 0.22 ± 0.02b MCP-1 mRNA 1.19 ± 0.20a 5.91 ± 0.75b 6.16 ± 1.06b 7.03 ± 1.49b TNFα mRNA 1.05 ± 0.09a 4.77 ± 0.48b 2.99 ± 0.45c 2.42 ± 0.23a,c Note. Data are mean ± SEM. Different letters represent significant (p < 0.05) difference between groups.