Intraperitoneal insulin is more potent than subcutaneous insulin at restoring hepatic insulin-like growth factor-I mRNA levels in the diabetic rat: a functional role for the portal vascular link

D L Russell-Jones, M Rattray, V J Wilson, R H Jones, P H Sönksen, C R Thomas

Research output: Contribution to journalArticle (Academic Journal)peer-review

27 Citations (Scopus)

Abstract

There is evidence that the hormonal control of hepatic IGF-I production is mediated by GH and insulin. To elucidate the role of these hormones further we administered s.c. or i.p. insulin (at 2.5 and 5.0 IU/day) and/or GH (0.8 IU/day) to rats made diabetic with streptozotocin 16 days previously. Hepatic IGF-I production was then assessed by quantifying hepatic IGF-I mRNA levels by autoradiography of Northern blots. Diabetes resulted in a fivefold reduction in hepatic IGF-I mRNA levels (optical density (OD) of the 0.7-1.1 kb band: controls, 1.3 +/- 0.09; diabetics, 0.28 +/- 0.08; P < 0.01), which was not significantly changed by treatment with s.c. insulin (OD: low dose, 0.55 +/- 0.05; high dose, 0.58 +/- 0.05) or low dose i.p. insulin (OD: 0.40 +/- 0.03). High dose i.p. insulin enhanced hepatic IGF-I mRNA levels (OD: 0.93 +/- 0.23) compared with diabetic rats (P < 0.01) and those given high dose s.c. insulin (P < 0.04), despite the blood glucose values being similar in the treated groups (i.p., 4.72 +/- 0.29 mmol/l; s.c., 3.32 +/- 0.03 mmol/l). Administration of GH alone partially restored the hepatic IGF-I mRNA level (OD: GH-treated, 1.00 +/- 0.05; diabetic, 0.28 +/- 0.08; P < 0.01), whilst having no effect on blood glucose values (diabetic, 36.35 +/- 0.45 mmol/l; GH-treated, 38.65 +/- 2.39 mmol/l). Additional administration of s.c. insulin completely restored IGF-I mRNA levels to those of controls (OD: low dose, 1.35 +/- 0.14; high dose, 1.27 +/- 0.18).(ABSTRACT TRUNCATED AT 250 WORDS)

Original languageEnglish
Pages (from-to)257-63
Number of pages7
JournalJournal of Molecular Endocrinology
Volume9
Issue number3
Publication statusPublished - Dec 1992

Keywords

  • Animals
  • Diabetes Mellitus, Experimental
  • Growth Hormone
  • Injections, Intraperitoneal
  • Injections, Subcutaneous
  • Insulin
  • Insulin-Like Growth Factor I
  • Liver
  • Male
  • RNA, Messenger
  • Rats
  • Rats, Sprague-Dawley
  • Comparative Study
  • Journal Article
  • Research Support, Non-U.S. Gov't

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