Effect of a combined trenbolone acetate and estradiol implant on steady-state IGF-I mRNA concentrations in the liver of wethers and the longissimus muscle of steers

J Anim Sci. 1998 Feb;76(2):491-7. doi: 10.2527/1998.762491x.

Abstract

Treatment of lambs (initial BW 28 kg) for 24 d with a combined implant containing 40 mg of trenbolone acetate (TBA) and 8 mg of estradiol (E2) increased ADG 25% (P < .05, n = 8) and feed efficiency 23% (P < .05, n = 2) compared with unimplanted lambs. By d 3 following implantation, sera from wethers implanted with TBA + E2 showed 32% (307 vs 233 ng/mL) increases (P < .001, n = 8) in IGF-I concentration compared with sera from unimplanted wethers. This increase was maintained throughout the entire 24-d study. Steady-state hepatic IGF-I mRNA levels were increased approximately 150% in implanted lambs compared with unimplanted lambs (P < .05, n = 4). These data suggest that liver may be the source of at least part of the increased circulating IGF-I in TBA + E2-implanted sheep. In steers implanted with Revalor-S (120 mg of TBA and 24 mg of E2) for 40 d, the steady-state concentration of IGF-I mRNA in the longissimus muscle was 68% greater than in the longissimus muscle of unimplanted steers (P = .013, n = 4). Consequently, increased local production of IGF-I by muscle tissue may play a role in increasing circulating IGF-I concentrations as well as an autocrine or paracrine role in stimulating muscle growth in steers implanted with Revalor-S.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anabolic Agents / administration & dosage
  • Anabolic Agents / pharmacology*
  • Animals
  • Cattle
  • DNA Primers
  • Drug Implants
  • Drug Interactions
  • Estradiol / administration & dosage
  • Estradiol / pharmacology*
  • Insulin-Like Growth Factor I / biosynthesis*
  • Insulin-Like Growth Factor I / metabolism
  • Liver / drug effects
  • Liver / metabolism*
  • Male
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism*
  • Orchiectomy
  • Polymerase Chain Reaction
  • RNA, Messenger / biosynthesis
  • Reference Values
  • Sheep
  • Time Factors
  • Transcription, Genetic / drug effects*
  • Trenbolone Acetate / administration & dosage
  • Trenbolone Acetate / analogs & derivatives*
  • Trenbolone Acetate / pharmacology

Substances

  • Anabolic Agents
  • DNA Primers
  • Drug Implants
  • RNA, Messenger
  • Estradiol
  • Insulin-Like Growth Factor I
  • Trenbolone Acetate