自発的レジスタンス運動と分岐鎖アミノ酸を豊富に含む高タンパク質間食がグルココルチコイド投与ラットの骨に及ぼす影響

概要

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Branched-chain amino acids (BCAAs) play a major role in suppression of skeletal muscle proteolysis. Therefore, dietary BCAAs might prevent age-related sarcopenia and osteopenia. We investigated the effect of voluntary resistance exercise (climbing) together with feeding high protein snack (60% casein) rich in BCAAs on bone mass and strength in rats injected with glucocorticoid as a model of age-related osteopenia. Fifty-five male Wistar rats were assigned to exercise or sedentary groups. One group was a control (Ct), which was a saline-injected group and the others were glucocorticoid-injected groups. These groups were further divided into groups that received no snack (GS and GE), casein snack (GSC and GEC), and BCAA snack (GSB and GEB). All rats were meal-fed at 8:30-9:30 h am/pm. The snack was fed at 12:30-13:30 h for 8 weeks. The exercise groups (GE, GEC and GEB) were allowed to climb voluntarily at 21:30-8:00 h. Final body weight, bone mass and strength were decreased by glucocorticoid injection. Climbing exercise increased bone mass and strength. Both high protein snacks did not influence bone mass and strength. These results suggest that resistance exercise is the most effective way to inhibit age-related osteopenia.
2007-02-28