Bradley RL, Jeon JY, Liu F-F, Maratos-Flier E. Voluntary exercise improves insulin sensitivity and adipose tissue inflammation in diet-induced obese mice. Am J Physiol Endocrinol Metab 295: E586-E594, 2008. First published June 24, 2008 doi:10.1152/ajpendo.00309.2007.-Exercise promotes weight loss and improves insulin sensitivity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Obesity correlates with increased production of inflammatory cytokines, which in turn, contributes to systemic insulin resistance. To test the hypothesis that exercise mitigates this inflammatory response, thereby improving insulin sensitivity, we developed a model of voluntary exercise in mice made obese by feeding of a high fat/high sucrose diet (HFD). Over four wk, mice fed chow gained 2.3 Ϯ 0.3 g, while HFD mice gained 6.8 Ϯ 0.5 g. After 4 wk, mice were subdivided into four groups: chow-no exercise, chow-exercise, HFD-no exercise, HFD-exercise and monitored for an additional 6 wk. Chow-no exercise and HFD-no exercise mice gained an additional 1.2 Ϯ 0.3 g and 3.3 Ϯ 0.5 g respectively. Exercising mice had higher food consumption, but did not gain additional weight. As expected, GTT and ITT showed impaired glucose tolerance and insulin resistance in HFD-no exercise mice. However, glucose tolerance improved significantly and insulin sensitivity was completely normalized in HFD-exercise animals. Furthermore, expression of TNF-␣, MCP-1, PAI-1 and IKK␤ was increased in adipose tissue from HFD mice compared with chow mice, whereas exercise reversed the increased expression of these inflammatory cytokines. In contrast, expression of these cytokines in liver was unchanged among the four groups. These results suggest that exercise partially reduces adiposity, reverses insulin resistance and decreases adipose tissue inflammation in diet-induced obese mice, despite continued consumption of HFD. insulin resistance; cytokine; adiposity; high-fat diet

Objective: The objective of this study was to investigate the association among adiposity, insulin resistance, and inflammatory markers [high‐sensitivity C‐reactive protein (hs‐CRP), interleukin (IL)‐6, and tumor necrosis factor (TNF)‐α] and adiponectin and to study the effects of exercise training on adiposity, insulin resistance, and inflammatory markers among obese male Korean adolescents. Research Methods and Procedures: Twenty‐six obese and 14 lean age‐matched male adolescents were studied. We divided the obese subjects into two groups: obese exercise group (N = 14) and obese control group (N = 12). The obese exercise group underwent 6 weeks of jump rope exercise training (40 min/d, 5 d/wk). Adiposity, insulin resistance, lipid profile, hs‐CRP, IL‐6, TNF‐α, and adiponectin were measured before and after the completion of exercise training. Results: The current study demonstrated higher insulin resistance, total cholesterol, LDL‐C levels, triglyceride, and inflammatory markers and lower adiponectin and HDL‐C in obese Korean male adolescents. Six weeks of increased physical activity improved body composition, insulin sensitivity, and adiponectin levels in obese Korean male adolescents without changes in TNF‐α, IL‐6, and hs‐CRP. Discussion: Obese Korean male adolescents showed reduced adiponectin levels and increased inflammatory cytokines. Six weeks of jump rope exercise improved triglyceride and insulin sensitivity and increased adiponectin levels.

No abstract

Several prospective cohort studies have examined the association between prediagnosis and/or postdiagnosis physical activity (PA) on colorectal cancer outcomes and reported conflicting results. To quantitatively assess this association, we have conducted a meta-analysis of prospective studies. Databases and reference lists of relevant studies were searched using MEDLINE and EMBASE up to January 2013. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random-effects models. For this meta-analysis, a total of seven prospective cohort studies were included. The analysis included 5,299 patients for prediagnosis PA and 6,348 patients for postdiagnosis PA, followed up over a period ranging from 3.8 to 11.9 years. The analyses showed that patients who participated in any amount of PA before diagnosis had a RR of 0.75 (95% CI: 0.65-0.87, p < 0.001) for colorectal cancer-specific mortality compared to patients who did not participate in any PA. Those who participated in high PA before diagnosis (vs. low PA) had a RR of 0.70 (95% CI: 0.56-0.87, p 5 0.002). Similarly, patients who participated in any PA after diagnosis had a RR of 0.74 (95% CI: 0.58-0.95, p 5 0.02) for colorectal cancer-specific mortality compared to patients who did not participate in any PA. Those who participated in high PA after diagnosis (vs. low PA) had a RR of 0.65 (95% CI: 0.47-0.92, p 5 0.01). Similar inverse associations of prediagnosis or postdiagnosis PA were found for all-cause mortality. In conclusion, both prediagnosis and postdiagnosis PA were associated with reduced colorectal cancer-specific mortality and all-cause mortality.Colorectal cancer is the third most common cancer in men and the second in women worldwide; it accounts for 8% of all cancer deaths.

No abstract

Genetics and environment contribute to the development of obesity, in both humans and rodents. However, the potential interaction between genes important in energy balance, strain background, and dietary environment has been only minimally explored. We investigated the effects of genetic ablation of melanin-concentrating hormone (MCH), a neuropeptide with a key role in energy balance, with chow and a high-fat diet (HFD) in two different mouse strains, one obesity-prone (C57BL/6) and the other obesity-resistant (129). Substantial differences were seen in wild-type (WT) animals of different strains. 129 animals had significantly lower levels of spontaneous locomotor activity than C57BL/6; however, 129 mice gained less weight on both chow and HFD. In both strains, deletion of MCH led to attenuated weight gain compared with WT counterparts, an effect secondary to increased energy expenditure. In both strains, feeding a HFD led to further increases in energy expenditure in both WT and MCH-KO mice; however, this increase was more pronounced in 129 mice. In addition, mice lacking MCH have a phenotype of increased locomotor activity, an effect also seen in both strains. The relative increase in activity in MCH(-/-) mice is modest in animals fed chow but increases substantially when animals are placed on HFD. These studies reinforce the important role of MCH in energy homeostasis and indicate that MCH is a plausible target for antiobesity therapy.

Studies have reported conflicting results on the association between body mass index (BMI) and prognosis of colorectal cancer. Therefore, we have conducted a meta-analysis of prospective studies, which examined the association of pre- and post-diagnostic BMI with colorectal cancer-specific mortality and all-cause mortality in patients with colorectal cancer. We searched Medline and EMBASE database published between 1970 and September 2014. A total of 508 articles were identified, of which 16 prospective cohort studies were included for the current meta-analysis. The analysis included 58,917 patients who were followed up over a period ranging from 4.9 to 20 years (median: 9.9 years). We found that being underweight before cancer diagnosis was associated with increased all-cause mortality (Relative risk [RR]: 1.63, 95% CI: 1.18–2.23, p < 0.01) and being obese (BMI ≥ 30 kg/m2) before cancer diagnosis was associated with increased colorectal cancer-specific mortality (RR: 1.22, 95% CI: 1.003–1.35, p < 0.01) and all-cause mortality (RR: 1.25, 95% CI: 1.14–1.36, p < 0.01). On the other hand, being underweight (RR: 1.33, 95% CI: 1.20–1.47, p < 0.01), obese (RR: 1.08, 95% CI: 1.03–1.3, p < 0.01), and class II/III obese (BMI ≥ 35 kg/m2; RR: 1.13, 95% CI: 1.04–1.23, p < 0.01) after diagnosis were associated with significantly increased all-cause mortality. Being obese prior to diagnosis of colorectal cancer was associated with increased colorectal cancer-specific mortality and all-cause mortality, whereas being obese after diagnosis was associated with increased all-cause mortality. The associations with being underweight may reflect reverse causation. Maintaining a healthy body weight should be discussed with colorectal cancer survivors.

No abstract