Effects of exercise training on skin collagen in growing mice / 体力科学

ABSTRACT

Male mice of dd-strain, at 4 weeks of age were used in the present study. The materials were divided into four groups; namely, mildly, moderately, severely trained and untrained. The treadmill exercise program for mildly, moderately and severely trained groups consisted of running at speeds of 6 m/min, 10m/min and running up a 10% grade at a speed of 12m/min for 10 min 5 times a week, respectively. The collagen content of the skin was measured by means of concentration of hydroxyproline. Moreover, the proportion of neutral salt-soluble (NSC), acetic acid-soluble (ASC) and insoluble collagen (ISC) in the skin was isolated. We attempted to study about the effects of physical activity on the metabolism of collagen by aging. Hydroxyproline concentration of the skin in untrained group increased rapidly until 6 weeks of age. Maximum hydroxyproline concentration was observed at 7 weeks of age in untrianed group. In three trained groups, maximum hydroxyproline concentration was observed at 9 weeks of age. The collagen content of the skin in the three groups was higher than that in untrained group at 9 and 11 weeks of age. The proportion of NSC, ASC and ISC of the skin varied with age in four groups. In the untrained group, the proportion of ISC increased with age and was recognized to reach 81.9% at 15 weeks of age. The proportion of NSC and ASC in both the moderately and severely trained groups indicated approximately 20% increase compared with that in the untrained group. This fact suggests that the degree of maturation of collagen is influenced by physical activity, especially, moderately and severely training. The authors conclude that continuous exercise training control the formation of intramolecular and intermolecular cross-links in skin collagen.