Early Life Androgen Administration Attenuates Aging Related Declines in Muscle Protein Synthesis.

Purpose: This study examined the acute and long-term effects of nandrolone decanoate (ND) on fractional synthetic rates (FSR). Methods: Male C57BL/6 mice were randomized into ND (n = 20) or sham (n = 20) groups. ND injections (10 g⋅kg-1⋅wk-1) started at 7 months of ages and continued for 6 wk. Ten animals from each group were randomly separated and examined 1 wk following drug cessation. The remaining animals were examined at 16 months of age. Animals were injected IP with 1.5 mL of deuterated water 24 h before euthanasia. The kidney, liver, heart, gastrocnemius, and soleus were extracted. Samples were analyzed for deuterated alanine enrichment in the bound protein and intracellular fraction by liquid chromatography tandem mass spectrometry to measure estimated FSR (fraction/day (F/D)) of mixed tissue. Results: One-way ANOVA, with treatment and age as fixed factors, indicated that kidney FSR was greater (P = 0.027) in ND (0.41 ± 0.02 F/D) than sham (0.36 ± 0.014F/D) and higher (P = 0.003) in young (0.42 ± 0.2 F/D) than old (0.35 ± 0.01 F/D). Liver and heart FSR values were greater (P ≤ 0.001) in young (0.79 ± 0.06 F/D and 0.13 ± 0.01 F/D, respectively) compared with old (0.40 ± 0.01 F/D and 0.09 ± 0.01 F/D, respectively), but not between ND and sham. Gastrocnemius FSR was (P ≤ 0.001) greater in young (0.06 ± 0.01 F/D) compared with old (0.03 ± 0.002 F/D), and greater (P = 0.006) in ND (0.05 ± 0.01 F/D) compared with sham (0.04 ± 0.003 F/D). Soleus FSR rates were greater (P = 0.050) in young (0.13 ± 0.01 F/D) compared with old (0.11 ± 0.003 F/D), but not between ND (0.12 ± 0.01 F/D) and sham (0.12 ± 0.01 F/D). Old animals who had received ND displayed elevated FSR in the gastrocnemius (P = 0.054) and soleus (P = 0.024). Conclusions: ND use in young adult animals appeared to maintain long-term elevations in FSR in muscle during aging. [ABSTRACT FROM AUTHOR]