caa a22 4500 463186338 CHVBK 20180406164854.0 cr unu---uuuuu 170326e20070901xx s 000 0 eng 10.1007/s00726-006-0404-0 doi (NATIONALLICENCE)springer-10.1007/s00726-006-0404-0 Suppression of myofibrillar proteolysis in chick skeletal muscles by α-ketoisocaproate [Elektronische Daten] [K. Nakashima, Y. Yakabe, A. Ishida, M. Yamazaki, H. Abe] Summary.: We previously reported that L-leucine suppresses myofibrillar proteolysis in chick skeletal muscles. In the current study, we compared the effects of L- and D-enantiomers of leucine on myofibrillar proteolysis in skeletal muscle of chicks. We also assessed whether leucine itself or its metabolite, α-ketoisocaproate (α-KIC), mediates the effects of leucine. Food-deprived (24 h) chicks were orally administered 225 mg/100 g body weight L-leucine, D-leucine or α-KIC and were sacrificed after 2 h. L-Leucine administration had an obvious inhibitory effect on myofibrillar proteolysis (plasma Nτ-methylhistidine concentration) in chicks while D-leucine and α-KIC were much more effective. We also examined the expression of the proteolytic-related genes (ubiquitin, proteasome, m-calpain and cathepsin B) by real-time PCR of cDNA in chick skeletal muscles. Ubiquitin mRNA expression was decreased by D-leucine and α-KIC but not L-leucine. Proteasome and m-calpain mRNA expressions as well as cathepsin B mRNA expression were likewise decreased by L-leucine, D-leucine and α-KIC. These results indicate that D-leucine and α-KIC suppress proteolytic-related genes, resulting in an decrease in myofibrillar proteolysis while L-leucine is much less effective in skeletal muscle of chicks, may be explain by conversion of D-leucine to α-KIC. Springer-Verlag, 2006 Keywords: Myofibrillar proteolysis - Leucine - α-Ketoisocaproate - Skeletal muscle - Chick nationallicence Nakashima K. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut Yakabe Y. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut Ishida A. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut Yamazaki M. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut Abe H. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut Amino Acids Springer-Verlag 33/3(2007-09-01), 499-503 0939-4451 33:3<499 2007 33 726 https://doi.org/10.1007/s00726-006-0404-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00726-006-0404-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nakashima K. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut NATIONALLICENCE 700 1- Yakabe Y. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut NATIONALLICENCE 700 1- Ishida A. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut NATIONALLICENCE 700 1- Yamazaki M. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut NATIONALLICENCE 700 1- Abe H. Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Japan aut NATIONALLICENCE 773 0- Amino Acids Springer-Verlag 33/3(2007-09-01), 499-503 0939-4451 33:3<499 2007 33 726 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer