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

Pampusch, Mary S.; White, Michael E.; Hathaway, Marcia; Baxa, T.J.; Chung, Ki Yong; Parr, S. L.; Johnson, B. J.; Weber, Wanda J; Dayton, William R

doi:10.2527/jas.2008-1085

Cited by 43 publications

(22 citation statements)

References 19 publications

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“…However, we elected to measure circulating IGF-I as an indirect positive marker of responses of cattle to growth-promoting steroid implants (Johnson et al, 1996b;Johnson et al, 1998). Additionally, it has been previously shown that implants containing E2 or T+E have a greater ability to stimulate circulating IGF-I than implants containing only TBA (Pampusch et al, 2008). Indeed, our results show a similar finding, and may indicate a greater capability for E2 to affect serum IGF-I concentrations.…”

Section: Discussionsupporting

confidence: 72%

“…It has been well documented that steroid growth promotant implants have positive effects on the efficiency and growth of livestock animals, and much is known about the cellular mechanisms behind the changes in muscle (Foutz et al, 1997;Johnson et al, 1998;Barton-Davis et al, 1999;Pampusch et al, 2008). However, there is no current literature on the impacts of steroid implantation on the cellular level of bone growth and resorption that are linked to the steroid-induced increases in bone maturity.…”

Section: Discussionmentioning

confidence: 99%

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Steroid implants and markers of bone turnover in steers

et al. 2012

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Steroidal implants are used extensively in beef cattle management to take advantage of welldocumented improvements in growth performance and efficiency. In addition to muscle growth, steroids bring about changes in bone and cartilage formation, hastening bone ageing. The current study was designed to test the hypothesis that recently identified indicators of bone and cartilage turnover could be detected in the peripheral circulation, and that these markers might reflect accelerated ageing effects of the widely used steroidal implants, trenbolone acetate (TBA) and estradiol-17β (E2). Thirty-two crossbred yearling steers were given one of four treatments to determine whether these markers of bone turnover could be detected and reflect steroid-induced bone maturity in the periphery: non-implanted controls; 25.7 mg estradiol-17β (E2); 120 mg trenbolone acetate (TBA); or 120 mg TBA and 24 mg E2 (T+E). Blood was collected on days 0, 7, 14 and 28 and serum analysed by ELISA for concentrations of IGF-I, osteocalcin, C-terminal telopeptides of Type I collagen (CTX-I) and C-terminal telopeptides of Type II collagen (CTX-II), as markers of the somatotropic-endocrine axis, bone formation, bone resorption and cartilage resorption, respectively. Circulating IGF-I was greater in E2 or T+E treated steers than controls on days 7 and 14. Osteocalcin was unaffected by treatment, but increased from day 0 on days 7, 14 and 28. Treatment did not affect CTX-I. However, CTX-II was elevated in the treated animals as opposed to the controls. Although these markers of bone and cartilage turnover are detectable, results suggest that implant-induced changes are not evident in the circulatory system.

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Steroid implants and markers of bone turnover in steers

et al. 2012

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“…Binding proteins specific for growth hormone and some, although not all, for IGF-I increase in plasma in response to elevated nutrient availability independent of treatment with exogenous growth hormone [37], and the same study indicated that elevated nutrient status actually reduced growth hormone in plasma. Concentration of IGF-I mRNA is elevated in longissimus muscle cells from animals previously administered exogenous E 2 [38,39], and muscle mRNA concentrations for the adipogenic regulators PPARγ and stearoyl CoA desaturase are reduced after administration of exogenous TBA [24]. In addition, both E 2 and TBA, which were used in combination in the present study, stimulate protein synthesis and reduce protein degradation in a dose-dependent manner when directly applied to fused satellite cell cultures [40,41].…”

Section: Resultsmentioning

confidence: 99%

Restricted nutrient intake does not alter serum-mediated measures of implant response in cell culture

Reinhardt

Lee

Thomson

et al. 2013

J Animal Sci Biotechnol

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BackgroundDuring nutritional stress, reduced intake may reduce the efficacy of anabolic implants. This study was conducted to evaluate basic cellular responses to a growth promotant implant at two intake levels.MethodsSixteen crossbred steers (293 ± 19.3 kg) were used to evaluate the impact of anabolic implants in either an adequate or a restricted nutritional state. Steers were trained to individual Calan gates, and then randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement. Treatments consisted of: presence or absence of an anabolic growth implant (Revalor-XS, 200 mg TBA and 40 mg estradiol; IMPLANT or CONTROL) and a moderate energy, pelleted, starting cattle diet fed at either 2.0 × or 1.0 × maintenance energy (NEM) requirements (HIGH or LOW). Serum (d 0, 14, and 28) was used for application to bovine muscle satellite cells. After treatment with the serum (20% of total media) from the trial cattle, the satellite cells were incubated for 72 h. Protein abundance of myosin heavy chain (MHC), phosphorylated extracellular signal-related kinase (phospho-ERK), and phosphorylated mammalian target of rapamycin (phospho-mTOR) were analyzed to determine the effects of implant, intake, and their interaction (applied via the serum).ResultsIntake had no effect on MHC (P = 0.85) but IMPLANT increased (P < 0.01) MHC abundance vs. CONTROL. Implant status, intake status, and the interaction had no effect on the abundance of phospho-ERK (P ≥ 0.23). Implanting increased phospho-mTOR (P < 0.01) but there was no effect (P ≥ 0.51) of intake or intake × implant.ConclusionsThe nearly complete lack of interaction between implant and nutritional status indicates that the signaling molecules measured herein respond to implants and nutritional status independently. Furthermore, results suggest that the muscle hypertrophic effects of anabolic implants may not be mediated by circulating IGF-1.

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“…Although the mechanisms involved in anabolic steroid stimulated muscle growth in beef cattle are not known with certainty, recent studies indicate that their effects on muscle satellite cells may play a prominent role (Johnson et al, 1998a;Kamanga-Sollo et al, 2008bPampusch et al, 2008). Treatment of yearling steers with Revalor-S (Merck Animal Health, Summit, NJ), an implant containing 120 mg of trenbolone acetate (TBA) and 24 mg of estradiol 17β (E2), significantly increases ADG, feed efficiency, LM area, and carcass protein (Johnson et al, 1998a).…”

Section: Effect Of a Combined Estradiol/trenbo-lone Acetate Implant Omentioning

confidence: 99%

MEAT SCIENCE AND MUSCLE BIOLOGY SYMPOSIUM—Role of satellite cells in anabolic steroid-induced muscle growth in feedlot steers1,2

Dayton

White

2014

Journal of Animal Science

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Both androgenic and estrogenic steroids are widely used as growth promoters in feedlot steers because they significantly enhance feed efficiency, rate of gain, and muscle growth. However, despite their widespread use relatively little is known about the biological mechanism by which androgenic and estrogenic steroids enhance rate and efficiency of muscle growth in cattle. Treatment of feedlot steers with a combined estradiol (E2) and trenbolone acetate (TBA) implant results in an increased number of muscle satellite cells, increased expression of IGF-1 mRNA in muscle tissue, and increased levels of circulating IGF-1. Similarly, treatment of bovine satellite cell (BSC) cultures with either TBA or E2 results in increased expression of IGF-1 mRNA, increased rates of proliferation and protein synthesis, and decreased rates of protein degradation. Effects of E2 on BSC are mediated at least in part through the classical E2 receptor, estrogen receptor-α (ESR1), the IGF-1 receptor (IGFR1), and the G protein-coupled estrogen receptor-1 (GPER-1), formerly known as G protein-coupled receptor-30 (GPR30). The effects of TBA appear to be primarily mediated through the androgen receptor. Based on current research results, it is becoming clear that anabolic steroid-enhanced bovine muscle growth involves a complex interaction of numerous pathways and receptors. Consequently, additional in vivo and in vitro studies are necessary to understand the mechanisms involved in this complex process. The fundamental information generated by this research will help in developing future, safe, and effective strategies to increase rate and efficiency of muscle growth in beef cattle.

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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

Cited by 43 publications

References 19 publications

Steroid implants and markers of bone turnover in steers

Steroid implants and markers of bone turnover in steers

Restricted nutrient intake does not alter serum-mediated measures of implant response in cell culture

MEAT SCIENCE AND MUSCLE BIOLOGY SYMPOSIUM—Role of satellite cells in anabolic steroid-induced muscle growth in feedlot steers1,2

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