Trenbolone (17B‐hydroxyestra‐4,9,11‐trien‐3‐one) protects against bone loss in gonadectomized male rodents

Abstract

We evaluated the effects of trenbolone‐enanthate (TREN) administration on bone turnover and on trabecular bone mineral density (BMD) in order to test the hypothesis that neither the 5alpha reduction nor the aromatization of androgens is required for bone maintenance. 3 month old male Fisher SAS rats received SHAM surgery + vehicle (V), gonadectomy (GNX) + V, GNX + Low (L) TREN (1.0 mg/week), GNX + Moderate (M) TREN (3.5 mg/week), GNX + High (H) TREN (7.0 mg/week), or GNX + supraphysiological testosterone (T) (7.0 mg/week) for 28 days. GNX completely ablated serum T in all groups except GNX + T, where serum T was 18‐fold above SHAM (p < 0.05). Serum trenbolone increased dose‐dependently in response to the graded doses of TREN (L: 8.3 ± 0.5; M: 50.4 ± 3.2; H: 96.6 ± 7.5 ng/ml; p < 0.05). GNX increased serum C‐telopeptide by 13% and osteocalcin by 40% (p < 0.05), indicating high‐turnover osteopenia; while androgen administration prevented this phenomenon. GNX also reduced total and trabecular BMD at the femoral metaphysis by 12% and 15% compared with SHAM, respectively (p < 0.05); while androgen administration prevented this loss similarly across groups, ultimately resulting in 7–16% greater total and trabecular BMD than GNX (p < 0.05). Our results indicate that TREN prevents hypogonadism induced bone loss and suggest that the bone protective effects of androgens can occur independently of the 5alpha reductase and aromatase enzymes.