Excessive Ethanol Intake in Mice Does Not Impair Recovery of Torque after Repeated Bouts of Eccentric Contractions

RAD140 (Testolone) negatively impacts skeletal muscle adaptation, frailty status and mortality risk in female mice

RAD140 is a selective androgen receptor modulator that produces anabolic effects within skeletal muscle. Thus, RAD140 may be effective at treating sarcopenia. No long-term studies have investigated how RAD140 influences strength in ageing muscle. This study aimed to determine how 10 weeks of RAD140 supplementation impacts strength, recovery from exercise, and overall health in ageing mice. Young and adult females were assigned to receive RAD140 (5 mg/kg) or a control solution. Dorsiflexor muscles were exposed to repeated bouts of eccentric contractions, and torque was measured before and after each bout. Adaptive potential and strength gains were calculated to assess the efficacy of RAD140 in muscle, while frailty status and mortality risk were used to measure health span. Supplementation of RAD140 increased frailty status and mortality risk in the young and adult treated groups compared to the controls (p ≤ 0.042). RAD140 decreased adaptive potential in young (p = 0.040) but not adult mice (p = 0.688). Torque did not differ between groups after 2-3 weeks of recovery (p ≥ 0.135). In conclusion, long-term RAD140 supplementation reduced indices of overall health and failed to improve strength in female mice, suggesting that RAD140 (at a 5mg/kg dosage) may be more detrimental than beneficial in delaying or preventing sarcopenia.

Longitudinal assessment of strength and body composition in a mouse model of chronic alcohol-related myopathy

BACKGROUND

Excessive, chronic alcohol consumption can result in muscle atrophy and weakness (i.e., alcoholic myopathy) that impairs the quality of life. However, the precise mechanisms responsible for ethanol's detrimental impact on skeletal muscle have not been fully elucidated, in part due because the time course of disease development and progression are not well established. Therefore, we examined muscle strength and body composition longitudinally using an established preclinical mouse model of chronic alcoholic myopathy.

METHODS

To establish a time course of chronic alcoholic myopathy, we fed High Drinking in the Dark (HDID) female mice (n = 7) 20% ethanol for ~32 weeks (following a 2-week ethanol ramping period). We assessed in vivo isometric contractility of the left ankle dorsiflexor and lean mass via NMR every 4 weeks. Outcomes were compared with age-matched control HDID mice that did not consume ethanol (n = 8).

RESULTS

At study completion, mice who consumed ethanol were 12% weaker than control mice (p = 0.015). Compared to baseline, consuming ethanol resulted in an acute transient reduction in dorsiflexion torque at Week 4 (p = 0.032) that was followed by a second, more sustained reduction at Week 20 (p < 0.001). Changes in lean mass paralleled those of dorsiflexor torque, with ~40% of the variance in dorsiflexor torque being explained by the variance in lean mass of the ethanol group (p < 0.001). Dorsiflexor torque normalized to lean mass (mN·m/g lean mass) did not differ between the ethanol and control groups from Weeks 4 to 32 (p ≥ 0.498).

CONCLUSIONS

These results indicate that reductions in muscle mass and strength due to chronic, excessive ethanol intake are dynamic, not necessarily linear, processes. Moreover, the findings confirm that ethanol-induced weakness is primarily driven by muscle atrophy (i.e., loss of muscle quantity). Future studies should consider how chronic alcoholic myopathy develops and progresses rather than identifying changes after it has been diagnosed.