Effect of dietary proteins on insulin-like growth factor-1 (IGF-1) messenger ribonucleic acid content in rat liver.
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.
Miura
Y
Y
Department of Agricultural Chemistry, Faculty of Agriculture, University of Tokyo, Japan.
Kato
H
H
Noguchi
T
T
D000818:Animals; D015152:Blotting, Northern; D004032:Diet; D004044:Dietary Proteins / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008099:Liver / Q000737:chemistry* / Q000187:drug effects; D008297:Male; D012333:RNA, Messenger / Q000032:analysis*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains
D004044:Dietary Proteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I