Higher Myonuclei Density in Muscle Fibers Persists Among Former Users of Anabolic Androgenic Steroids

Abstract

Context: No information exists on the long-lasting effects of supraphysiological anabolic androgenic steroids (AASs) usage on the myocellular properties of human skeletal muscle in previous AAS users.

Objective: We hypothesized that former AAS users would demonstrate smaller myonuclei domains (ie, higher myonuclei density) than matched controls.

Methods: A community-based cross-sectional study in men aged 18-50 years engaged in recreational strength training. Muscle biopsies were obtained from the m. vastus lateralis. Immunofluorescence analyses were performed to quantify myonuclei density and myofiber size.

Results: Twenty-five males were included: 8 current and 7 previous AAS users and 10 controls. Median (25th-75th percentiles) accumulated duration of AAS use was 174 (101-206) and 140 (24-260) weeks in current and former AAS users, respectively (P = .482). Geometric mean (95% CI) elapsed duration since AAS cessation was 4.0 (1.2; 12.7) years among former AAS users. Type II muscle fibers in former AAS users displayed higher myonuclei density and DNA to cytoplasm ratio than controls, corresponding to smaller myonuclei domains (P = .013). Longer accumulated AAS use (weeks, log2) was associated with smaller myonuclei domains in previous AAS users: beta-coefficient (95% CI) -94 (-169; -18), P = .024. Type I fibers in current AAS users exhibited a higher amount of satellite cells per myofiber (P = .031) than controls.

Conclusion: Muscle fibers in former AAS users demonstrated persistently higher myonuclei density and DNA to cytoplasm ratio 4 years after AAS cessation suggestive of enhanced retraining capacity.

Keywords: androgenic anabolic steroids; muscle memory; myonuclear density.