17a Trenbolone [BSA]

The impact of exposure by water to a model androgen, 17 beta-trenbolone (TRB), was assessed in fathead minnows using an integrated molecular approach. This included classical measures of endocrine exposure such as impacts on testosterone (T), 17 beta-estradiol (E2), and vitellogenin (VTG) concentrations in plasma, as well as determination of effects on the hepatic metabolome using proton nuclear magnetic resonance spectroscopy. In addition, the rates of production of T and E2 in ovary explants were measured, as were changes in a number of ovarian gene transcripts hypothesized to be relevant to androgen exposure. A temporally intensive 16-d test design was used to assess responses both during and after the TRB exposure (i.e., depuration/recovery). This strategy revealed time-dependent responses in females (little impact was seen in the males), in which changes in T and E2 production in the ovary, as well as levels in plasma, declined rapidly (within 1 d), followed shortly by a return to control levels. Gene expression measurements revealed dynamic control of transcript levels in the ovary and suggested potential mechanisms for compensation during the exposure phase of the test. Proton nuclear magnetic resonance spectroscopy revealed a number of hepatic metabolite changes that exhibited strong time and dose dependence. Furthermore. TRB appeared to induce the hepatic metabolome of females to become more like that of males at both high test concentrations of TRB (472 ng/L) and more environmentally relevant levels (33 ng/L). Environ. Toxicol. Chem. 2011;30:319-329. (C) 2010 SETAC

This experiment evaluated the dose and payout pattern of trenbolone acetate (TBA) and estradiol-17 beta (E-2) on LM mRNA expression of adenosine monophosphate-activated protein kinase-alpha (AMPK-alpha), C/EBP beta, G protein-coupled receptor 41(GPR41), G protein-coupled receptor 43 (GPR43), PPAR gamma, and stearoyl CoA desaturase (SCD) in finishing feedlot steers as indicators of adipogenesis and marbling development. British x Continental steers (n = 168; 14 pens/treatment; initial BW = 362 kg) were used in a randomized complete block design. Treatments included: no implant (NI), Revalor-S (REV-S; 120 mg TBA + 24 mg E-2), or Revalor-XS (REV-X; delayed release implant: 80 mg TBA + 16 mg E-2 [uncoated], 120 mg TBA + 24 mg E-2 [coated], 200 mg TBA + 40 mg E-2 [total]). Steers were fed 1 time daily for an average of 164 d. The LM biopsies were collected (1 steer/pen) on d -1, 27, 55, and 111 relative to timing of implant. Total RNA was isolated from each sample and real-time quantitative PCR was used to measure quantity of AMPK-alpha, C/EBP beta, GPR41, GPR43, PPAR gamma, and SCD mRNA. No implant x day interactions were detected (P >= 0.19) in this experiment. Day impacted the mRNA expression of all adipogenic genes (P <= 0.02). The main effect of implant tended (P = 0.09) to influence expression of AMPK-alpha, REV-X had an 8.8% increase over NI and an 18.7% increase over REV-S. Implant influenced (P = 0.03) mRNA expression of GPR41, expression of GPR41 for the REV-X treatment was not different (P > 0.10) from NI, and both were greater (P <= 0.05) than REV-S (1.13, 1.00, and 0.67 +/- 0.224 arbitrary units) for REV-X, NI, and REV-S, respectively. Implant also influenced (P = 0.02) expression of GPR43, expression of GPR43 for REV-X was not different (P > 0.10) from NI, and both were greater (P <= 0.05) than REV-S (1.27, 1.07, and 0.72 +/- 0.234 arbitrary units) for REV-X, NI, and REV-S, respectively. Implant influenced (P = 0.02) mRNA expression of PPAR gamma in LM tissue, expression of PPAR. for REV-X was not different (P > 0.10) from NI, and both were greater (P <= 0.05) than REV-S (1.09, 1.02, and 0.69 +/- 0.195 arbitrary units) for REV-X, NI, and REV-S, respectively. The REV-X steers received the greatest anabolic dose of TBA + E-2 without detriment to marbling scores. The increased mRNA expression of adipogenic genes for REV-X steers suggest that the delayed and gradual release of anabolic stimulants associated with REV-X might have mitigated decreases in marbling generally attributed to multiple combined TBA + E-2 implants.