Kidney insulin-like growth factor-I mRNA levels are increased in postpubertal diabetic rats

J Endocrinol. 1991 Apr;129(1):5-10. doi: 10.1677/joe.0.1290005.

Abstract

Diabetes-associated renal enlargement is more marked in postpubertal than prepubertal rats, and in the postpubertal rat, is associated with increased kidney insulin-like growth factor-I (IGF-I) levels for the first 2 days. In order to determine whether local IGF-I production is the cause of this increase in tissue levels, IGF-I mRNA levels were determined in pre- and postpubertal Sprague-Dawley rats made diabetic with streptozotocin (STZ) and in control rats. RNA was extracted from kidneys and livers of rats at 0 h, 6 h, 12 h and days 1, 2, 3 and 7 after STZ injection. After Northern blotting and hybridization with an oligonucleotide probe complementary to an E domain of the IGF-I cDNA, four distinct bands (7.4, 4.8, 1.8 and 1.0 kb) were found. Densitometric analyses of the most prominent bands (7.4 and 1.0 kb), after normalization for 18S ribosomal RNA content, revealed a 50-100% increase in the kidneys of postpubertal diabetic rats compared with postpubertal controls 12 h after STZ injection (P less than 0.05, diabetes vs control). Between days 2 and 7, kidney IGF-I mRNA levels in postpubertal diabetic rats fell to approximately 50% of control levels (P less than 0.05, diabetes vs control). In contrast, kidney IGF-I mRNA levels in the prepubertal diabetic rats remained unchanged over the 7 days. Liver IGF-I mRNA levels did not rise during the first 24 h and fell to approximately 60% of control levels by day 7 in both pre- and postpubertal diabetic rats (P less than 0.05, diabetes vs control). Increased local IGF-I production may underlie the initiation of renal enlargement associated with diabetes mellitus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Blotting, Northern
  • DNA Probes
  • Diabetes Mellitus, Experimental / genetics*
  • Gene Expression / physiology*
  • Insulin-Like Growth Factor I / genetics*
  • Kidney / chemistry
  • Kidney / physiology*
  • Liver / chemistry
  • Liver / physiology
  • Male
  • Molecular Sequence Data
  • RNA, Messenger / analysis
  • Rats
  • Rats, Inbred Strains
  • Sexual Maturation / genetics*

Substances

  • DNA Probes
  • RNA, Messenger
  • Insulin-Like Growth Factor I