Differential Effects Of RAD140 Treatment On Rat Tibialis Anterior And Plantaris Muscle Cross-Sectional Areas

PURPOSE: Selective Androgen Receptor Modulators (SARMs) are a class of therapeutic compounds that have potent anabolic effects, stimulate skeletal muscle hypertrophy, and may provide benefits in muscle wasting conditions such as sarcopenia or cancer cachexia. Recently, SARM treatment has been increasingly popular with athletes in hopes to improve performance and muscular strength. Of particular interest to strength athletes is testolone (RAD140), a novel SARM known to stimulate androgen-sensitive tissues like skeletal muscle. However, the impact of RAD140 alone, in the absence of any additional androgenic stimulus such as strength training or functional overload using a synergist ablation model, requires further exploration. METHODS: Either RAD140 (1 mg/kg,) or vehicle (5% methylcellulose, w/v) was provided in drinking water for 14 days. Then, rat plantaris (PLA) and tibialis anterior (TA) muscles were collected, trimmed free of connective tissue, weighed, and prepared for histochemical analyses of myofiber areas. Serial sections of each muscle were cut at 14 μM, stained using standard hematoxylin and eosin techniques, and myofiber cross-sectional areas (CSA) were quantified using a light microscope and ImageJ software. RESULTS: Interestingly, RAD140 treatment had differential effects on CSA. For example, average CSA was significantly larger in PLA fibers from RAD140-treated rats compared to vehicles-treated rats (33,935 + 2413 vs. 24,219 + 992 AU, respectively, p < .05). In contrast, average CSA in the TA muscle was unchanged due to RAD140 treatment compared to vehicle treated rats (31,546 + 3229 vs. 28,021 + 4327, respectively). CONCLUSIONS: These data may suggest that muscle recruitment, activation patterns, load challenge, or muscle fiber type composition may also play key roles in the differential response on fiber CSA secondary to RAD140 treatment. AFP Innovation Fund