Effect of anabolic steroids on skeletal muscle mass during hindlimb suspension

Abstract

The efficacy of anabolic steroid treatment [0.3 or 0.9 mg nandrolone decanoate (Deca-Durabolin) per day] was examined in the context of sparing rodent fast-twitch plantaris and slow-twitch soleus muscle weight, sparing subcellular protein, and altering isomyosin expression in response to hindlimb suspension. Female rats were assigned to four groups (7 rats/group for 6 wk): 1) normal control (NC), 2) normal steroid (NS), 3) normal suspension (N-SUS), and 4) suspension steroid (SUS-S). Compared with control values for the plantaris and soleus muscles, suspension induced 1) smaller body and muscle weight (P less than 0.05), 2) losses in myofibril content (mg/muscle, P less than 0.05), and 3) shifts in the relative expression (expressed as %of total isomyosin) of isomyosins which favored lesser slow myosin and greater fast myosin isotypes (P less than 0.05). Steroid treatment of suspended animals (SUS-S vs. N-SUS) partially spared body and muscle weight (P less than 0.05) and spared plantaris but not soleus myofibril content (mg/muscle, P less than 0.05). However, steroid treatment did not modify the isomyosin pattern induced by suspension. In normal rats (NS vs. NC), steroid treatment enhanced body and plantaris muscle weight but not soleus weight (P less than 0.05) and did not alter isomyosin expression in either muscle type. Collectively these data suggest that in young female rats anabolic steroids 1) enhance the body weight and the weight of a fast-twitch ankle extensor in normal rats, 2) ameliorate the loss in body weight, fast-twitch muscle weight and protein content and slow-twitch muscle weight associated with hindlimb suspension.(ABSTRACT TRUNCATED AT 250 WORDS)

Overload-induced androgen receptor expression in the aged rat hindlimb receiving nandrolone decanoate

“…Only the aged Sol RNA-to-DNA ratio was significantly reduced by nandrolone decanoate treatment, which appears to be mainly due to an increase in the muscle DNA pool. Regardless of age, Plan muscle mass or protein content did not respond to anabolic steroid administration with or without functional overload, which is in agreement with the findings of others (36,45). Several variables appear to modulate anabolic steroid action on skeletal muscle, including animal gender, animal age, primary muscle phenotype, anabolic steroid type, and anabolic steroid dosage.…”

“…However, the nandrolone decanoate administration used in the presentstudy did significantly increase rat prostate weight in the aged rats but not in the 5-mo-old animals (12). An interactive effect on muscle mass has been shown between anabolic steroid administration and mechanical overload in both resistance-trained humans and rat skeletal muscle subject to disuse atrophy (45). The present study also finds an interaction between muscle loading and anabolic steroid administration; however, this interaction was dependent on both the age of the animal and the primary muscle phenotype.…”

“…Understanding the response of primarily fast and slow muscle phenotypes to aging and overload are important endeavors because human muscle is a heterogeneous mix of slow and fast fibers, and fiber-type composition has been shown to be altered with advancing age (31). Both the Sol and Plan muscles respond to functional overload with a rapid and large increase in muscle mass, which consists mainly of enlarged muscle fiber cross-sectional area (28,45). However, rat hindlimb muscle's capacity to enlarge in response to functional overload is compromised by advancing age (5).…”

“…The regulation of skeletal muscle mass by anabolic steroidinduced cellular signaling and the potential for interactions with mechanical signaling pathways have not been well defined. Studies examining exogenous testosterone administration's effect on young rat skeletal muscle mass have reported mixed results, and even less is understood about targets of altered gene expression (1,7,45,48). Differences in results between studies are likely due to drug type, dosage, and administration schedules.…”

“…Exogenous testosterone administration with muscle loading can synergistically increase skeletal muscle mass in healthy and diseased humans (4). A synergistic relationship between testosterone and muscle loading is present in functionally overloaded rat muscle subject to disuse atrophy (45). Anabolic steroid administration can also abolish unloaded atrophy in the rat quadriceps muscle (48).…”