Effects of implants of trenbolone acetate, estradiol, or both, on muscle insulin-like growth factor-I, insulin-like growth factor-I receptor, estrogen receptor-α, and androgen receptor messenger ribonucleic acid levels in feedlot steers1
Autor: | T.J. Baxa, Bradley J. Johnson, Mary S. Pampusch, Wanda J Weber, K. Y. Chung, Michael E White, S. L. Parr, Marcia Hathaway, William R Dayton |
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Rok vydání: | 2008 |
Předmět: |
medicine.medical_specialty
medicine.medical_treatment Estrogen receptor General Medicine Biology Androgen receptor Insulin-like growth factor Endocrinology Trenbolone Internal medicine Feedlot Genetics medicine Animal Science and Zoology Implant Receptor Estrogen receptor alpha Food Science medicine.drug |
Zdroj: | Journal of Animal Science. 86:3418-3423 |
ISSN: | 1525-3163 0021-8812 |
Popis: | We previously showed that a combined trenbolone acetate (TBA)/estradiol-17beta (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)-alpha 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-alpha, 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 0.47) 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. |
Databáze: | OpenAIRE |
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