J. Retention of sedentary obese visceral white adipose tissue phenotype with intermittent physical activity despite reduced adiposity.

AimBased on its regulatory action on glucagon-like peptide 1, dipeptidyl peptidase IV (DPP-IV) has increasingly been linked to Type 2 diabetes. However, there is no evidence as to how this normal modulatory enzyme leads to pathology. It is thought that DPP-IV is affected by the development of obesity, which is a common precursor to Type 2 diabetes. Little is known about the relationship between DPP-IV activity in plasma and specific body composition measures.Main methodsIn the current study, plasma DPP-IV activity and body composition measures were collected from 111 healthy subjects between the ages of 19 and 70 years old for analysis.Key findingsThe mean plasma DPP-IV activity was 35.9U/L ± 12.3, falling within normal reference value range presented by Durinx et al. DPP-IV activity was negatively correlated with absolute body fat mass, but absolute lean mass was positively correlated. Consistent with the findings, DPP-IV activity was also negatively correlated with absolute gynoid fat (p = 0.0047). DPP-IV activity did not have a significant correlation with absolute android fat mass, visceral adipose tissue, BMI, and age.SignificanceFrom these results, it can be concluded that high activity of DPP-IV is not indicative of pathology, and specific body composition components may influence soluble DPP-IV activity in the blood.

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Adipose tissue (AT) dysfunction plays a pivotal role in the development of insulin resistance in obesity. Regular physical activity (PA) is effective in reducing AT mass and inflammation; however, whether intermittent PA affords beneficial effects is unknown. The purpose of this study was to evaluate the influence of intermittent PA on adiposity and retroperitoneal AT expression of genes related to inflammation and oxidative stress. Male C57BL/6 mice (age 5 weeks) were randomly assigned to four groups (n=10/group): low‐fat diet sedentary (LFD‐SED), high‐fat diet sedentary (HFD‐SED), HFD regular PA (HFD‐RPA), and HFD intermittent PA (HFD‐IPA) for 24 weeks. All animals were single‐caged. RPA mice had access to voluntary running wheels throughout the study period, whereas IPA mice had access to running wheels for three‐week intervals (i.e., 3 weeks on/3 weeks off) throughout the study period. Both HFD‐RPA and HFD‐IPA were associated with a similar reduction in retroperitoneal AT mass (~‐24%, p<0.05) relative to HFD‐SED. However, HFD‐RPA, but not HFD‐IPA, exhibited a decrease in retroperitoneal adipose mRNA markers of inflammation (F4/80, CD11c, leptin, VCAM‐1) and oxidative stress (p22phox and p47phox). Collectively, these data suggest that episodic PA over a prolonged period of time leads to a reduction in adiposity albeit with retention of a “sedentary obese” white AT phenotype.