Growth hormone reduces glucose transport but not GLUT-1 or GLUT-4 in adult and old rats

Am J Physiol. 1995 May;268(5 Pt 1):E902-9. doi: 10.1152/ajpendo.1995.268.5.E902.

Abstract

The primary purpose of this study was to investigate the influence of administration of recombinant-derived human growth hormone (rhGH) to adult male rats of several ages (9, 20, and 31 mo) on skeletal muscle glucose transport. Rats were injected with rhGH (0.7 mg/kg) or vehicle twice daily for 10 days. The rhGH treatment led to a doubling of circulating insulin-like growth factor I levels at each age. Skeletal muscle glucose transport activity was evaluated in isolated epitrochlearis muscle with use of 3-O-methylglucose at three insulin concentrations (0, 100, and 20,000 microU/ml). The results indicate that, after 10 days of rhGH administration, 1) an approximately 20-30% reduction in basal glucose transport activity was evident in muscles from every age group, 2) the ability of a submaximally effective insulin concentration (100 microU/ml) to increase glucose transport activity above basal values was not significantly reduced in any age group, 3) maximal insulin-stimulated glucose transport activity (with 20,000 microU/ml) was significantly reduced (approximately 40%) by rhGH treatment only in the oldest rats, and 4) the alterations in glucose transport activity occurred despite no change in skeletal muscle GLUT-1 or GLUT-4 protein levels.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3-O-Methylglucose
  • Aging / metabolism*
  • Animals
  • Biological Transport / drug effects
  • Blood Glucose / analysis
  • Body Weight / drug effects
  • Glucose / metabolism*
  • Glucose Transporter Type 1
  • Glucose Transporter Type 4
  • Growth Hormone / pharmacology*
  • Hybridization, Genetic
  • Insulin / blood
  • Insulin-Like Growth Factor I / metabolism
  • Male
  • Methylglucosides / metabolism
  • Monosaccharide Transport Proteins / metabolism*
  • Muscle Proteins*
  • Muscle, Skeletal / metabolism
  • Rats
  • Rats, Inbred F344

Substances

  • Blood Glucose
  • Glucose Transporter Type 1
  • Glucose Transporter Type 4
  • Insulin
  • Methylglucosides
  • Monosaccharide Transport Proteins
  • Muscle Proteins
  • Slc2a1 protein, rat
  • Slc2a4 protein, rat
  • 3-O-Methylglucose
  • Insulin-Like Growth Factor I
  • Growth Hormone
  • Glucose