Epigallocatechin-3-gallate improves plantaris muscle recovery after disuse in aged rats

Aging exacerbates muscle loss and slows the recovery of muscle mass and function after disuse. In this study we investigated the potential that epigallocatechin-3-gallate (EGCg), an abundant catechin in green tea, would reduce signaling for apoptosis and promote skeletalmuscle recovery in the fast plantarismuscle and the slowsoleus muscle after hindlimb suspension (HLS) in senescent animals. Fischer 344 x Brown Norway inbred rats (age 34 months) received either EGCg (50 mg/kg body weight), or water daily by gavage. One group of animals received HLS for 14 days and a second group of rats received 14 days ofHLS, then theHLSwas removed and they recovered fromthis forced disuse for 2 weeks. Animals that received EGCg over the HLS followed by 14 days of recovery, had a 14% greater plantaris muscle weight (p < 0.05) as compared to the animals treated with the vehicle over this same period. Plantaris fiber area was greater after recovery in EGCg (2715.2 +/- 113.8 mu m(2)) vs. vehicle treated animals (1953.0 +/- 41.9 mu m(2)). In addition, activation of myogenic progenitor cells was improved with EGCg over vehicle treatment (7.5% vs. 6.2%) in the recovery animals. Compared to vehicle treatment, the apoptotic index was lower (0.24% vs. 0.52%), and the abundance of pro-apoptotic proteins Bax (- 22%), and FADD (- 77%) was lower in EGCg treated plantaris muscles after recovery. While EGCg did not prevent unloading-induced atrophy, it improvedmuscle recovery after the atrophic stimulus in fast plantarismuscles. However, this effectwas muscle specific because EGCg had nomajor impact in reversingHLS-induced atrophy in the slowsoleusmuscle of old rats. (C) 2013 Elsevier Inc. All rights reserved.