Effects of aging and dietary restriction on tissue protein synthesis: relationship to plasma insulin-like growth factor-1.
Insulin-like growth factor-1 (IGF-1) decreases with age in many species and appears to have an important role in the age-related decline in capacity for protein synthesis with age. The goals of these studies were to determine whether (a) ad libitum fed mice demonstrate age-related decreases in IGF-1, (b) the relationship between IGF-1 and age-related changes in protein synthetic capacity in ad libitum fed animals, and (c) whether moderate dietary restriction (which increases both life span and protein synthetic capacity) delays age-related changes in protein synthesis and plasma IGF-1. These studies indicate that (a) in ad libitum fed animals, plasma IGF-1 decreases with age between 10 and 15 months and moderate dietary restriction decreases plasma IGF-1 in young but not older animals, and (b) the temporal changes in protein synthesis are tissue specific; moderate dietary restriction either increases or prevents the age-related decline in tissue protein synthesis. Results suggest that in normal aging, decreases in IGF-1 are associated with the decline in protein synthesis but that other regulatory mechanisms appear to have an important role in this process. Dietary restriction decreases plasma IGF-1 in young animals and either increases protein synthesis or prevents the age-related decline in protein synthesis, suggesting that the effects of dietary restriction are not mediated via increases in plasma IGF-1.
Sonntag
W E
WE
Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Winston-Salem, NC 27157-1083.
Lenham
J E
JE
Ingram
R L
RL
D000375:Aging / Q000378:metabolism*; D000818:Animals; D003964:Diaphragm / Q000378:metabolism; D004032:Diet; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism; D014176:Protein Biosynthesis; D013047:Specific Pathogen-Free Organisms; D013997:Time Factors; D014018:Tissue Distribution; D014443:Tyrosine / Q000378:metabolism
D014443:Tyrosine; D010649:Phenylalanine; D007334:Insulin-Like Growth Factor I