17β-hydroxyestra-4,9,11-trien-3-one (trenbolone) is a potent synthetic testosterone analogue which does not undergo 5α reduction to more potent metabolites (46). As such, trenbolone may induce less growth in prostate and other androgenic tissues which highly express 5α reductase. This is in contrast to testosterone, which has approximately three fold greater potency in androgenic tissues, which highly express 5α reductase (63), due to its conversion to dihydrotestosterone (DHT).
The primary purpose of this study was to determine the effects of trenbolone-enanthate (TREN; a slowly released trenbolone ester) on a variety of androgen sensitive tissues, including skeletal muscle, bone, visceral adiposity, hemoglobin, and the prostate of rodents. Because trenbolone is selectively metabolized to weaker androgens in vivo, they hypothesized that TREN will produce dose-dependent anabolic effects in skeletal muscle, bone, and fat that are at least equal to those of supraphysiological testosterone, while producing a smaller increase in hemoglobin and less growth of the prostate. Their findings indicate that TREN has advantages over supraphysiologic testosterone and supports the need for future pre-clinical studies examining the viability of TREN as an option for androgen replacement therapy.
Yarrow JF, Conover CF, McCoy SC, et al. 17β-hydroxyestra-4,9,11-trien-3-one (Trenbolone) Exhibits Tissue Selective Anabolic Activity: Effects on Muscle, Bone, Adiposity, Hemoglobin, and Prostate. American Journal of Physiology - Endocrinology And Metabolism. 17β-hydroxyestra-4,9,11-trien-3-one (Trenbolone) Exhibits Tissue Selective Anabolic Activity: Effects on Muscle, Bone, Adiposity, Hemoglobin, and Prostate — AJP - Endo
Selective androgen receptor modulators (SARMs) now under development can protect against muscle and bone loss, without causing prostate growth or polycythemia. 17β-hydroxyestra-4,9,11-trien-3-one (trenbolone), a potent testosterone analogue, may have SARM-like actions because, unlike testosterone, trenbolone does not undergo tissue-specific 5α reduction to form more potent androgens. We tested the hypothesis that trenbolone-enanthate (TREN) might prevent orchiectomy-induced losses in muscle and bone and visceral fat accumulation, without increasing prostate mass or resulting in adverse hemoglobin elevations.
Male F344 rats aged three months underwent orchiectomy or remained intact and were administered graded doses of TREN, supraphysiologic testosterone-enanthate, or vehicle for 29 days. In both intact and orchiectomized animals, all TREN doses and supraphysiologic testosterone-enanthate augmented androgen-sensitive levator ani/bulbocavernosus muscle mass by 35-40% above Shams (p≤0.001), and produced a dose-dependent partial protection against orchiectomy-induced total and trabecular bone mineral density losses (p<0.05) and visceral fat accumulation (p<0.05). The lowest doses of TREN successfully maintained prostate mass and hemoglobin concentrations at Sham levels in both intact and orchiectomized animals; whereas supraphysiologic testosterone-enanthate and high-dose TREN elevated prostate mass by 84% and 68%, respectively (p<0.01).
In summary, low dose administration of the non-5α reducible androgen TREN maintains prostate mass and hemoglobin concentrations near the level of Shams, while producing potent myotrophic actions in skeletal muscle and partial protection against orchiectomy-induced bone loss and visceral fat accumulation. Our findings indicate that TREN has advantages over supraphysiologic testosterone and supports the need for future pre-clinical studies examining the viability of TREN as an option for androgen replacement therapy.
