抄録
Protein kinase B (PKB) and calcineurin (CaN) are both postulated to play important roles in integrating intracellular signaling in skeletal muscle in response to both disuse and increased muscle loading. These experiments investigated the age-related differences in signal transduction of the downstream pathways of both PKB and CaN during a period of recovery following immobilization-induced muscle atrophy. The hindlimb muscles of one leg in young (10 weeks) and adult (40 weeks) were immobilized in plantar flexion position using a plaster cast for 10 days. At 1-10 days after the removal of plaster cast, both the atrophic and the contralateral plantaris muscles were removed. Immobilization resulted in significant muscle atrophy in both young and adult animals. Muscle mass in young animal recovered up to -90% following 10-days of recovery period, but not in adult animals. The levels of phosphorylated p70S6K were significantly higher in both animals following 1-day of recovery, with the greatest changes seen in young rats. Muscle levels of phosphorylated S6 (pS6) in young rats were higher in all of recovery period, but pS6 in adult rats returned to control levels by day 10 of recovery. CaN levels in adult animals were higher at recovery day 10, but not in young animals. These results show that the signaling pathways during recovery in atrophied plantaris muscle immobilization differ in young and adult muscles. [Jpn J Physiol 55 Suppl:S117 (2005)]
