Acute bout of exercise downregulates thioredoxin-interacting protein expression in rat contracting skeletal muscles.

We previously reported that in rat skeletal muscle, disuse (i.e., decreased muscle contractile activity) rapidly increases thioredoxin-interacting protein (TXNIP), which is implicated in the reduced glucose uptake. Accordingly, we sought herein to (a) determine the effect of exercise (i.e., increased muscle contractile activity) on muscle TXNIP protein expression, and (b) elucidate the mechanisms underlying the changes of TXNIP protein expression in response to exercise. Rat epitrochlearis and soleus muscles were dissected out after an acute bout of 3-hr swimming (without weight loading) or 3-hr treadmill running (15% grade at 9m/min). In a separate protocol, the isolated epitrochlearis and soleus muscles were incubated for 3 hr with AMP-dependent protein kinase activator AICAR. Immediately after the cessation of the 3-hr swimming, the TXNIP protein was decreased in epitrochlearis but not in soleus muscle. Conversely, 3-hr treadmill running decreased the TXNIP protein in soleus but not in epitrochlearis muscle. TXNIP protein was decreased concomitantly with reduced postexercise muscle glycogen, showing that a decrease in TXNIP protein expression occurs in muscles that are recruited during exercise. In addition, 3-hr incubation with AICAR decreased TXNIP protein in both isolated epitrochlearis and soleus muscles. Our results suggest that (a) an acute bout of exercise downregulates TXNIP protein expression in rat contracting skeletal muscles, and (b) the reduction in TXNIP protein expression in contracting muscles is probably mediated by AMPK activation, at least in part.

Educational Interventions and Evaluation for Obesity Prevention in Preschool Children in Local Communities.

Educational interventions for obesity prevention from early childhood is one of the important measures in health promotion policies, especially in locations where obesity and overweight in school and preschool children are prevalent, such as in the Aomori Prefecture. The Aomori Prefecture government started a new demonstration project in FY 2014 that targeted children in nursing schools for the prevention of obesity through both population approaches (nutrition/physical activity education and nutrition management in lunch programs) and individual approaches to solving overweight in children. Our study group developed a data management tool to routinely accumulate data on measured body height and weight. We also developed educational materials with growth charts for nutritional education of guardians, and summary sheets showing the distributions of degree of obesity and prevalence of overweight/obesity in age-sex groups for use in assessment in each nursing school. To promote and evaluate the demonstration project, we offered the data management tool to all nursing schools in the prefecture for nutritional education and management in the nursing schools and asked them to anonymously submit data to build a prefecture-based monitoring dataset. Around 70% (310 institutes) of the institutes responded to this request, and we developed a longitudinal dataset with about 4,000 children in each of the 3-, 4-, and 5-year-old cohorts. This first revealed the prevalence of overweight in preschool children in the entire prefecture. The dataset will be further utilized for evaluating the effectiveness of educational interventions in preschool settings in local communities.

Increased postexercise insulin sensitivity is accompanied by increased AS160 phosphorylation in slow-twitch soleus muscle.

A single bout of exercise can enhance insulin-stimulated glucose uptake in both fast-twitch (type II) and slow-twitch (type I) skeletal muscle for several hours postexercise. Akt substrate of 160 kDa (AS160) is most distal insulin signaling proteins that have been proposed to contribute to the postexercise enhancement of insulin action in fast-twitch muscle. In this study, we examined whether the postexercise increase in insulin action of glucose uptake in slow-twitch muscle is accompanied by increased phosphorylation of AS160 and its paralog TBC1D1. Male Wistar rats (~1-month-old) were exercised on a treadmill for 180 min (9 m/min). Insulin (50 µU/mL)-stimulated glucose uptake was increased at 2 h after cessation of exercise in soleus muscle composed of predominantly slow-twitch fibers. This postexercise increase in insulin action of glucose uptake was accompanied by increased phosphorylation of AS160 (detected by phospho-Thr642 and phospho-Ser588 antibody). On the other hand, prior exercise did not increase phosphorylation of TBC1D1 (detected by phospho-Thr590) at 2 h postexercise. These results suggest the possibility that an enhancement in AS160 phosphorylation but not TBC1D1 phosphorylation is involved with increased postexercise insulin action of glucose uptake in slow-twitch muscle.