Interaction of exercise and diet on GLUT-4 protein and gene expression in type I and type II rat skeletal muscle

We determined the interaction of exercise and diet on glucose transporter (GLUT-4) protein and mRNA expression in type I (soleus) and type II [extensor digitorum longus (EDL)] skeletal muscle. Forty-eight Sprague Dawley rats were randomly assigned to one of two dietary conditions: high-fat (FAT, n =24) or high-carbohydrate (CHO, n =24). Animals in each dietary condition were allocated to one of two groups: control (NT, n =8) or a group that performed 8 weeks of treadmill running (4 sessions week^–1 of 1000 m @ 28 m min^–1 , RUN, n =16). Eight trained rats were killed after their final exercise bout for determination of GLUT-4 protein and mRNA expression: the remainder were killed 48 h after their last session for measurement of muscle glycogen and triacylglycerol concentration. GLUT-4 protein expression in NT rats was similar in both muscles after 8 weeks of either diet. However, there was a main effect of training such that GLUT-4 protein was increased in the soleus of rats fed with either diet (P < 0.05) and in the EDL in animals fed with CHO (P < 0.05). There was a significant diet–training interaction on GLUT-4 mRNA, such that expression was increased in both the soleus (100% ↑P < 0.05) and EDL (142% ↑P < 0.01) in CHO-fed animals. Trained rats fed with FAT decreased mRNA expression in the EDL (↓ 45%, P < 0.05) but not the soleus (↓ 14%, NS). We conclude that exercise training in CHO-fed rats increased both GLUT-4 protein and mRNA expression in type I and type II skeletal muscle. Despite lower GLUT-4 mRNA in muscles from fat-fed animals, exercise-induced increases in GLUT-4 protein were largely preserved, suggesting that control of GLUT-4 protein and gene expression are modified independently by exercise and diet.

UCP3 protein expression is lower in type I, IIa and IIx muscle fiber types of endurance-trained compared to untrained subjects

Uncoupling protein 3 (UCP3) is a muscle mitochondrial protein believed to uncouple the respiratory chain, producing heat and reducing aerobic ATP production. Our aim was to quantify and compare the UCP3 protein levels in type I, IIa and IIx skeletal muscle fibers of endurance-trained (Tr) and healthy untrained (UTr) individuals. UCP3 protein content was quantified using Western blot and immunofluorescence. Skeletal muscle fiber type was determined by both an enzymatic ATPase stain and immunofluorescence. UCP3 protein expression measured in skeletal muscle biopsies was 46% lower ( P=0.01) in the Tr compared to the UTr group. UCP3 protein expression in the different muscle fibers was expressed as follows; IIx>IIa>I in the fibers for both groups ( P<0.0167) but was lower in all fiber types of the Tr when compared to the UTr subjects ( P<0.001). Our results show that training status did not change the skeletal muscle fiber hierarchical UCP3 protein expression in the different fiber types. However, it affected UCP3 content more in type I and type IIa than in the type IIx muscle fibers. We suggest that this decrease may be in relation to the relative improvement in the antioxidant defense systems of the skeletal muscle fibers and that it might, as a consequence, participate in the training induced improvement in mechanical efficiency.

Family average income and diagnosed Type 2 diabetes in urban and rural residents in regional mainland China.

Aims: To explore the relationship between family average income (FAI; an index of socio-economic status) and Type 2 diabetes in a region of mainland China. Methods: Population-based cross-sectional study, conducted between October 2000 and March 2001 in administrative villages (n = 45) randomly selected from three urban districts and two rural counties of NanJing municipality, mainland China, with a regional population of 5.6 million. Participants were all local residents aged ≥ 35 years old (n = 29 340); 67.7% from urban areas, 32.3% from rural areas, 49.8% male and 50.2% female. Results: The response rate of eligible participants was 90.1%. The overall prevalence of self-reported Type 2 diabetes was 1.9%. After adjustment for possible confounding variables (age, gender, area of residence, body mass index, educational level, smoking status, occupational and leisure-time physical activity), participants in the higher and middle FAI categories were more than twice as likely to have Type 2 diabetes as those in the lower FAI category. Conclusions: The prevalence of Type 2 diabetes is positively related to socio-economic status (indexed by FAI) in Chinese at the population level. After controlling for potential confounding factors, people in higher socio-economic status groups are more likely to have Type 2 diabetes. These associations are consistent with other effects of epidemiological transition and identify a need for preventive initiatives.

Effects of high-intensity progressive resistance training on self-reported health status in older persons with type 2 diabetes

Purpose: To evaluate the influence of high-intensity progressive resistance training (PRT) on self-reported physical and mental health in older persons with type 2 diabetes.

Methods: We performed a 12-month RCT with 36 overweight men and women with type 2 diabetes (aged 60-80 years) who were randomly assigned to a moderate weight-loss diet plus PRT (PRT&WL) or a moderate weight-loss diet plus a control (stretching) program (WL). Gymnasium-based training for 6 months was followed by an additional 6 months of home-based training. The SF-36 (v1) questionnaire was used to obtain physical (PCS) and mental (MCS) health component summary scores at baseline, 6 and 12 months.

Results: Subject retention was 81% and 72% after 6 and 12 months respectively. Exercise adherence during gymnasium- and home-based training was 88% and 73% for the PRT&WL group, and 85% and 78.1% for the WL group respectively. In a regression model adjusted for age and sex, PCS improved in the PRT&WL group compared to the WL group after 6 months of gymnasium-based training (2.3 versus -2.0, p = 0.05), which persisted after 12 months training (0.7 versus -4.1, p = 0.03). There were no between-group differences at 6 or 12 months for the MCS.

Conclusion: High-intensity PRT was effective in improving self-reported physical health, but not mental health. PRT provides an effective exercise alternative in lifestyle management for older adults with type 2 diabetes.