Effect of Dietary Proteins on Insulin-Like Growth factor-1 (IGF-1) Messenger Ribonucleic Acid Content in Rat Liver

Br J Nutr. 1992 Mar;67(2):257-65. doi: 10.1079/bjn19920029.


Effects of quantity and quality of dietary proteins on plasma immunoreactive insulin-like growth factor-1 (IGF-1) concentration, and content of IGF-1 mRNA in rat liver were investigated in rats. Plasma immunoreactive IGF-1 concentration in rats given a casein diet was higher than that in rats given a soya-bean-protein or protein-free diet. The IGF-1 mRNA content in liver was estimated by the Northern blot hybridization technique employing 32P-labelled rat IGF-1 complementary DNA (cDNA). At least four molecular species of IGF-1 mRNA of different molecular weight were found in rat liver. The sizes were 0.8-1.2, 2.0, 3.6-4.0 and 7.4 kb. Most of the mRNA species decreased in the livers of rats given a gluten diet (120 g gluten/kg diet) compared with rats given the casein diet. In particular, mRNA of 7.4 kb decreased markedly. When rats were fed on the protein-free diet, mRNA of all species decreased significantly. The estimated IGF-1 mRNA in the livers of rats fed on the gluten or protein-free diet was almost 0.4 of that of the rats given the casein diet. Feeding the soya-bean-protein diet did not result in a marked effect on the hepatic content of mRNA species of IGF-1. The results showed that liver IGF-1 mRNA content is sensitively regulated by quantity and nutritional quality of dietary proteins.

MeSH terms

  • Animals
  • Blotting, Northern
  • Diet
  • Dietary Proteins / pharmacology*
  • Insulin-Like Growth Factor I / genetics*
  • Liver / chemistry*
  • Liver / drug effects
  • Male
  • RNA, Messenger / analysis*
  • Radioimmunoassay
  • Rats
  • Rats, Inbred Strains


  • Dietary Proteins
  • RNA, Messenger
  • Insulin-Like Growth Factor I