title: Epigallocatechin-3-gallate increases autophagy signaling in resting and unloaded plantaris muscles but selectively suppresses autophagy protein abundance in reloaded muscles of aged rats.
abstract: We have previously found that Epigallocatechin-3-gallate (EGCg), an abundant catechin in green tea, reduced apoptotic signaling and improved muscle recovery in response to reloading after hindlimb suspension (HS). In this study, we investigated if EGCg altered autophagy signaling in skeletal muscle of old rats in response to HS or reloading after HS. Fischer 344×Brown Norway inbred rats (age 34months) were given 1ml/day of purified EGCg (50mg/kg body weight), or the same sample volume of the vehicle by gavage. One group of animals received HS for 14days and the second group of rats received 14days of HS, then the HS was removed and they were allowed to recover by ambulating normally around the cage for two weeks. EGCg decreased a small number of autophagy genes in control muscles, but it increased the expression of other autophagy genes (e.g., ATG16L2, SNCA, TM9SF1, Pink1, PIM-2) and HS did not attenuate these increases. HS increased Beclin1, ATG7 and LC3-II/I protein abundance in hindlimb muscles. Relative to vehicle treatment, EGCg treatment had greater ATG12 protein abundance (35.8%, P<0.05), but decreased Beclin1 protein levels (-101.1%, P<0.05) after HS. However, in reloaded muscles, EGCg suppressed Beclin1 and LC3-II/I protein abundance as compared to vehicle treated muscles. EGCg appeared to "prime" autophagy signaling before and enhance autophagy gene expression and protein levels during unloading in muscles of aged rats, perhaps to improve the clearance of damaged organelles. However, EGCg suppressed autophagy signaling after reloading, potentially to increase the recovery of hindlimb muscles mass and function after loading is restored.
authors.affiliation: Divison of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506, United States; Kuju Agricultural Research Center, Graduate School of Agriculture Science, Kyushu University, Naoiri-gun Kuju-cho 4045-4, 878-0201, Oita, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Divison of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506, United States; Research Faculty of Agriculture, Laboratory of Animal Function and Nutrition, Hokkaido University, Kita-9 Nishi-9, Sapporo, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Divison of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506, United States.
authors.forename: Junaith S
authors.initials: JS
authors.lastname: Mohamed
authors.affiliation: Kuju Agricultural Research Center, Graduate School of Agriculture Science, Kyushu University, Naoiri-gun Kuju-cho 4045-4, 878-0201, Oita, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Gotoh
authors.affiliation: Discovery Technology, Abbott Nutrition, Columbus, OH 43219, United States.
authors.forename: Suzette L
authors.initials: SL
authors.lastname: Pereira
authors.affiliation: Divison of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506, United States. Electronic address: salway@hsc.wvu.edu.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Alway
mesh_terms: D000375:Aging / Q000502:physiology*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001343:Autophagy / Q000187:drug effects*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D019417:Hindlimb Suspension; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D009133:Muscular Atrophy / Q000473:pathology; D009929:Organ Size; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D000975:Antioxidants; D002392:Catechin; C045651:epigallocatechin gallate
keywords: Aging; Autophagy; Muscle reloading; Muscle wasting; Nutrition