These findings suggest that exercise stimulates SPARC secretion from muscle tissues and that SPARC inhibits colon tumorigenesis by increasing apoptosis.

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The prevalence of IBS was higher among nursing and medical students, and further interventional studies are needed to improve IBS symptoms.

Background: MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional gene regulation. miRNAs are taken in by intracellular exosomes, secreted into circulation, and taken up by other cells, where they regulate cellular functions. We hypothesized that muscle-enriched miRNAs existing in circulation mediate beneficial metabolic responses induced by exercise. To test this hypothesis, we measured changes in muscle-enriched circulating miRNAs (c-miRNAs) in response to acute and chronic aerobic exercise.Methods: Eleven healthy young men (age, 21.5 ± 4.5 y; height, 168.6 ± 5.3 cm; and body weight, 62.5 ± 9.0 kg) performed a single bout of steady-state cycling exercise at 70% VO2max for 60 min (acute exercise) and cycling training 3 days per week for 4 weeks (chronic exercise). Blood samples were collected from the antecubital vein before and after acute and chronic exercise. RNA was extracted from serum, and the levels of muscle-enriched miRNAs (miR-1, miR-133a, miR-133b, miR-206, miR-208b, miR-486, and miR-499) were measured.Results: All of these miRNAs, except for miR-486, were found at too low copy numbers at baseline to be compared. miR-486 was significantly decreased by both acute (P = 0.013) and chronic exercise (P = 0.014). In addition, the change ratio of miR-486 due to acute exercise showed a significant negative correlation with VO2max for each subject (R = 0.58, P = 0.038).Conclusion: The reduction in circulating miR-486 may be associated with metabolic changes during exercise and adaptation induced by training.

T. The microRNA miR-696 regulates PGC-1␣ in mouse skeletal muscle in response to physical activity. Am J Physiol Endocrinol Metab 298: E799 -E806, 2010. First published January 19, 2010 doi:10.1152/ajpendo.00448.2009 are small noncoding RNAs involved in posttranscriptional gene regulation that have been shown to be involved in growth, development, function, and stress responses of various organs. The purpose of this study was to identify the miRNA response to physical activity, which was related to functions such as nutrient metabolism, although the miRNAs involved are currently unknown. C57BL/6 mice were divided into exercise and control groups. The exercise group performed running exercise, with a gradual increase of the load over 4 wk. On the other hand, to examine the effect of muscle inactivity, the unilateral hindlimbs of other mice were fixed in a cast for 5 days. Microarray analysis for miRNA in gastrocnemius revealed that miR-696 was markedly affected by both exercise and immobilization, showing opposite responses to these two interventions. Peroxisome proliferator-activated receptor-␥ coactivator-1␣ (PGC-1␣), which was increased by exercise and decreased by immobilization in the protein level, was predicted as a target regulated by miR-696. In cultured myocytes, intracellular miR-696 variation led to negative regulation of PGC-1␣ protein along with the expression of mRNAs for downstream genes. In addition, we found decreases in the biogenesis of mitochondria and fatty acid oxidation in miR-696-overexpressing myocytes compared with normal control myocytes. These observations demonstrate that miR-696 is a physical activity-dependent miRNA involved in the translational regulation of PGC-1␣ and skeletal muscle metabolism in mice.peroxisome proliferator-activated receptor-␥ coactivator-1␣; exercise; immobilization; muscle metabolism; mitochondria biogenesis; microarray PHYSICAL ACTIVITY IMPROVES VARIOUS BODILY FUNCTIONS, including metabolism, cardiovascular function, and immune function. The skeletal muscles comprise the major organ supporting physical activity, and muscle function is altered dramatically by contractile activity. Numerous studies have shown that daily exercise improves muscle energy metabolism and strength (9, 21, 23), along with changes of the expression or activity of muscle enzymes and proteins, as well as alterations of their mRNA transcription. Conversely, low levels of physical activity and immobilization induce the atrophy of skeletal muscle and decrease its metabolic capacity (9,15,20,52), with the expression/activity of many proteins and mRNAs being negatively regulated by inactivity compared with the effect of exercise. Although considerable progress has been made in understanding the functions of muscles that are associated with physical activity, the underlying molecular pathways remain obscure, especially those related to translational regulation. In fact, the level of expression of a particular mRNA does not necessarily reflect the abundance of the corresponding protein becau...

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Dietary antioxidants may attenuate oxidative damage from strenuous exercise in various tissues. Beneficial effects of the antioxidant astaxanthin have been demonstrated in vitro, but not yet in vivo. We investigated the effect of dietary supplementation with astaxanthin on oxidative damage induced by strenuous exercise in mouse gastrocnemius and heart. C57BL/6 mice (7 weeks old) were divided into groups: rested control, intense exercise, and exercise with astaxanthin supplementation. After 3 weeks of exercise acclimation, both exercise groups ran on a treadmill at 28 m/min until exhaustion. Exercise-increased 4-hydroxy-2-nonenal-modified protein and 8-hydroxy-2'-deoxyguanosine in gastrocnemius and heart were blunted in the astaxanthin group. Increases in plasma creatine kinase activity, and in myeloperoxidase activity in gastrocnemius and heart, also were lessened by astaxanthin. Astaxanthin showed accumulation in gastrocnemius and heart from the 3 week supplementation. Astaxanthin can attenuate exercise-induced damage in mouse skeletal muscle and heart, including an associated neutrophil infiltration that induces further damage.

Protons dissociated from organic acids in cells are partly buffered. If not, they are transported to the extracellular fluid through the plasma membrane and buffered in circulation or excreted in urine and expiration gas. Several transporters including monocarboxylate transporters and Na+/H+ exchanger play an important role in uptake and output of protons across plasma membranes in cells of metabolic tissues including skeletal muscle and the liver. They also contribute to maintenance of the physiological pH of body fluid. Therefore, impairment of these transporters causes dysfunction of cells, diseases, and a decrease in physical performance associated with abnormal pH. Additionally, it is known that fluid pH in the interstitial space of metabolic tissues is easily changed due to little pH buffering capacitance in interstitial fluids and a reduction in the interstitial fluid pH may mediate the onset of insulin resistance unlike blood containing pH buffers such as Hb (hemoglobin) and albumin. In contrast, habitual exercise and dietary intervention regulate expression/activity of transporters and maintain body fluid pH, which could partly explain the positive effect of healthy lifestyle on disease prognosis.