Dietary protein-induced renal growth: Correlation between renal IGF-I synthesis and hyperplasia

E. Chin, C. A. Bondy

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Insulin-like growth factor I (IGF-I) and IGF binding protein 1 (IGFBP-1) mRNAs are colocalized in the medullary thick ascending limb (MTAL) of the rat nephron, a segment that undergoes selective growth in response to elevated dietary protein. In the present study, rats were fed isocaloric diets containing variable protein content (6-40%) for 1-7 days, and changes in fractional renal weight, MTAL length, and regional DNA synthesis were assayed and compared with local changes in IGF-I/IGFBP-1 mRNAs, as determined by quantitative in situ hybridization. Rats switched to high-protein diets demonstrated increased IGF-I and decreased IGFBP-1 mRNA levels in MTALs, whereas those switched to low protein showed inverse changes. The increase in renal IGF-I mRNA was maximal at 2 days and was closely paralleled by significant increases in fractional renal weight, DNA synthesis, and MTAL length. Similar changes were seen in vasopressin-deficient Brattleboro and growth hormone (GH)-deficient dwarf rats in response to high-protein diets, suggesting that the effects of dietary protein in this model are not mediated by vasopressin or GH. The close spatial and temporal correlation between changes in renal IGF-I expression and changes in regional growth parameters strongly supports a role for locally produced IGF-I in the induction of protein-induced renal growth.

Original languageEnglish (US)
Pages (from-to)1037-1045
Number of pages9
JournalAmerican Journal of Physiology - Cell Physiology
Volume266
Issue number4 part 1
StatePublished - Apr 1 1994

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Keywords

  • deoxyribonucleic acid synthesis
  • hyperplasia
  • hypertrophy
  • insulin-like growth factor binding protein 1
  • messenger ribonucleic acid
  • nephron
  • osmotic load
  • thick ascending limb

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

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