IGFBP mRNA expression in small intestine of rat during postnatal development.
In contrast to the adult gut, the immature intestine is refractory to subcutaneously infused insulin-like growth factor I (IGF-I). IGF binding protein (IGFBP) mRNA expression was characterized in intestinal tissues from 6-, 19-, and 90-day-old rats to determine if changes in local expression could account for this age-related change in IGF-I potency. For all age groups, IGFBP-3 to -6, but not IGFBP-1 or -2, were detected by Northern blot analysis. IGFBP-3, -4, and -5 were more intensely expressed in the 6-day-old rat intestine compared with weanling or adult tissue. In contrast, IGFBP-6 expression peaked at the time of weaning. In situ hybridization showed IGFBP-3 to -6 expression was confined to cells of the lamina propria and submucosa and also in the muscularis layer for IGFBP-5. Furthermore, the pattern of IGFBP-5 localization in the intestine changed with development. The findings indicate that the expression of IGFBP-3 to -6 is higher in the immature intestine compared with the adult intestine, suggesting locally produced IGFBPs may inhibit systemically derived IGF-I action in the intestine. Therefore, changes to local IGFBP expression may contribute to the varying response of the rat intestine to IGF-I peptides during postnatal development.
Shoubridge
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Child Health Research Institute and Cooperative Research Centre for Tissue Growth and Repair, North Adelaide, South Australia 5006, Australia. cheryl.shoubridge@adelaide.edu.au
Steeb
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Read
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D000375:Aging; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015870:Gene Expression; D017403:In Situ Hybridization; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000032:analysis / Q000235:genetics; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000032:analysis / Q000235:genetics; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000032:analysis / Q000235:genetics; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000032:analysis / Q000235:genetics; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000032:analysis / Q000235:genetics; D018976:Insulin-Like Growth Factor Binding Protein 6 / Q000032:analysis / Q000235:genetics; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis / Q000097:blood / Q000235:genetics*; D007421:Intestine, Small / Q000737:chemistry / Q000254:growth & development*; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar
D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D018974:Insulin-Like Growth Factor Binding Protein 4; D018975:Insulin-Like Growth Factor Binding Protein 5; D018976:Insulin-Like Growth Factor Binding Protein 6; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger