Influence of age and long-term dietary restriction on plasma insulin-like growth factor-1 (IGF-1), IGF-1 gene expression, and IGF-1 binding proteins

J Gerontol. 1991 Sep;46(5):B180-7. doi: 10.1093/geronj/46.5.b180.


The purpose of these studies was to determine more accurately the relationship between IGF-1 and life span, and to determine whether moderate dietary caloric restriction alters the age-related changes in IGF-1. Studies included an assessment of plasma IGF-1, hepatic IGF-1 mRNA, and plasma IGF-1 binding proteins (IGF-1-BP). Rats (6, 12, 22, and 28 months of age) were fed ad libitum or maintained on a diet 60% of ad libitum. In ad libitum fed animals, plasma IGF-1 decreased by 20% between 6 and 28 months of age. Similar age-related declines were observed in dietary restricted animals but levels were generally 14-25% lower at each age group. IGF-1 mRNA levels demonstrated similar decreases with age in ad libitum fed animals, but in dietary restricted animals, levels plateaued at 22 and 28 months. IGF-1 binding protein analysis revealed 3 bands at approximate molecular weights of 40k, 30k, and 24k. All bands demonstrated a decrease in relative IGF-1-BP concentration with age, as well as a decrease in the 40k and 30k binding proteins after dietary restriction. These results indicate that (a) aging in ad libitum fed animals is associated with decreases in plasma IGF-1, IGF-1-BP, and IGF-1 mRNA levels; and (b) long-term dietary restriction decreases plasma IGF-1 and IGF-1-BP levels in each age group although the age-associated decreases in IGF-1 mRNA levels are prevented by dietary restriction.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aging / blood*
  • Aging / genetics
  • Animals
  • Autoradiography
  • Blotting, Western
  • Carrier Proteins / blood*
  • DNA Probes
  • Diet*
  • Electrophoresis, Polyacrylamide Gel
  • Gene Expression*
  • Immunoblotting
  • Insulin-Like Growth Factor Binding Proteins
  • Insulin-Like Growth Factor I / analysis*
  • Insulin-Like Growth Factor I / genetics
  • Liver / chemistry
  • Longevity
  • Male
  • Nucleic Acid Hybridization
  • RNA / analysis
  • RNA, Messenger / analysis*
  • Rats
  • Rats, Inbred BN
  • Rats, Inbred F344
  • Somatomedins / analysis*
  • Time Factors


  • Carrier Proteins
  • DNA Probes
  • Insulin-Like Growth Factor Binding Proteins
  • RNA, Messenger
  • Somatomedins
  • RNA
  • Insulin-Like Growth Factor I