Effects of implants of trenbolone acetate, estradiol, or both, on muscle insulin-like growth factor-I, insulin-like growth factor-I receptor, estrogen receptor-ά, and androgen receptor messenger ribonucleic acid levels in feedlot steers

M. S. Pampusch, M. E. White, M. R. Hathaway, T. J. Baxa, K. Y. Chung, S. L. Parr, B. J. Johnson, W. J. Weber, W. R. Dayton

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

We previously showed that a combined trenbolone acetate (TBA)/estradiol-17ß (E2) implant significantly increases IGF-I mRNA levels in the LM of feedlot steers by 28 d after implantation. Here we compare the effects of E2 (25.7 mg), TBA (120 mg), and combined TBA (120 mg) / E2 (24 mg) implants on IGF-I, IGF-I receptor (IGFR-1), estrogen receptor (ER)-α and androgen receptor (AR) mRNA levels in the LM of steers. Twenty yearling crossbred steers with an average initial BW of 421.1 ± 3.6 kg were stratified by BW and randomly assigned to 1 of 4 treatments: 1) nonimplanted, control; 2) implanted with TBA and E2; 3) implanted with E2; or 4) implanted with TBA. Steers were weighed weekly starting on d 0, and muscle biopsy samples were taken from each steer on d 0 (before implantation), 7, 14, and 28. Ribonucleic acid was prepared from each sample and real-time reverse transcription-PCR was used to determine the levels of IGF-I, IGFR-1, ER-α, and AR mRNA. Body weight of implanted steers, adjusted by using d-0 BW as a covariant, tended (P = 0.09) to be greater than that of control steers. On d 7 and 28, IGF-I mRNA levels were greater (58 and 78%, respectively; P < 0.009) in E2-implanted animals than in control steers. Similarly, on d 28 the LM IGF-I mRNA level was 65% greater (P = 0.017) in TBA/E2-implanted steers than in control animals. In contrast, the TBA implant did not increase (P = 0.99) LM IGF-I mRNA levels after 28 d of implantation. Muscle IGFR-1, AR, and ER-α mRNA levels were not different (P > 0.47) in any of the treated groups compared with the control group. These data suggest that E2 is responsible for the increased muscle IGF-I mRNA level observed in steers implanted with a combined TBA/E2 implant.

Original languageEnglish (US)
Pages (from-to)3418-3423
Number of pages6
JournalJournal of animal science
Volume86
Issue number12
DOIs
StatePublished - Dec 2008

Keywords

  • Bovine
  • Estradiol-17ß
  • Insulin-like growth factor-I
  • Muscle
  • Trenbolone acetate

Fingerprint Dive into the research topics of 'Effects of implants of trenbolone acetate, estradiol, or both, on muscle insulin-like growth factor-I, insulin-like growth factor-I receptor, estrogen receptor-ά, and androgen receptor messenger ribonucleic acid levels in feedlot steers'. Together they form a unique fingerprint.

  • Cite this