Insulin regulates insulin-like growth factor I mRNA in rat hepatocytes

Am J Physiol. 1991 Jun;260(6 Pt 1):E846-51. doi: 10.1152/ajpendo.1991.260.6.E846.

Abstract

To evaluate the regulatory role of growth hormone (GH) and insulin on insulin-like growth factor I (IGF-I) mRNA levels, we employed primary rat hepatocytes. Cells were incubated for 16 h with 10 nM insulin, 10 nM GH, or a combination thereof, and IGF-I mRNA levels were analyzed by Northern blotting. Insulin results in 2.5-fold and GH in 3.8-fold higher IGF-I mRNA levels than hormone-free controls, and a combination of insulin and GH had an additive effect (6.7-fold). The effect of 10 nM insulin was constant at variable GH concentrations. Therefore, GH and insulin affect IGF-I mRNA levels independently of each other. The half-maximal effective dose of insulin was 4.7 X 10(-10) M, and, in kinetic experiments, insulin was effective within 2 h. These findings demonstrate that insulin modulates hepatic IGF-I production by a direct regulation of the transcript levels of IGF-I.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Gene Expression Regulation / drug effects
  • Growth Hormone / pharmacology
  • Insulin / pharmacology*
  • Insulin-Like Growth Factor I / genetics*
  • Insulin-Like Growth Factor I / pharmacology
  • Kinetics
  • Liver / drug effects
  • Liver / physiology*
  • Male
  • Models, Biological
  • Nucleic Acid Hybridization
  • RNA, Messenger / drug effects
  • RNA, Messenger / genetics*
  • RNA, Messenger / isolation & purification
  • Rats
  • Rats, Inbred Strains

Substances

  • Insulin
  • RNA, Messenger
  • Insulin-Like Growth Factor I
  • Growth Hormone