title: Ursolic acid stimulates mTORC1 signaling after resistance exercise in rat skeletal muscle.
abstract: A recent study identified ursolic acid (UA) as a potent stimulator of muscle protein anabolism via PI3K/Akt signaling, thereby suggesting that UA can increase Akt-independent mTOR complex 1 (mTORC1) activation induced by resistance exercise via Akt signaling. The purpose of the present study was to investigate the effect of UA on resistance exercise-induced mTORC1 activation. The right gastrocnemius muscle of male Sprague-Dawley rats aged 11 wk was isometrically exercised via percutaneous electrical stimulation (stimulating ten 3-s contractions per set for 5 sets), while the left gastrocnemius muscle served as the control. UA or placebo (PLA; corn oil only) was injected intraperitoneally immediately after exercise. The rats were killed 1 or 6 h after the completion of exercise and the target tissues removed immediately. With placebo injection, the phosphorylation of p70(S6K) at Thr(389) increased 1 h after resistance exercise but attenuated to the control levels 6 h after the exercise. On the other hand, the augmented phosphorylation of p70(S6K) was maintained even 6 h after exercise when UA was injected immediately after exercise. A similar trend of prolonged phosphorylation was observed in PRAS40 Thr(246), whereas UA alone or resistance exercise alone did not alter its phosphorylation level at 6 h after intervention. These results indicate that UA is able to sustain resistance exercise-induced mTORC1 activity.
authors.affiliation: The Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga, Japan;
authors.forename: Riki
authors.initials: R
authors.lastname: Ogasawara
authors.forename: Koji
authors.initials: K
authors.lastname: Sato
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Higashida
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakazato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujita
mesh_terms: D000818:Animals; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014315:Triterpenes / Q000494:pharmacology*; D000097245:Ursolic Acid
chemical_list: D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D014315:Triterpenes; D000097245:Ursolic Acid
keywords: exercise; intracellular signaling; muscle hypertrophy; nutrition; supplement