The myostatin null mutation and clenbuterol administration elicit additive effects in mice

Abstract

In mice, the myostatin (Mstn) null mutation and treatment with clenbuterol both increase muscle growth and decrease fat mass. Our objective was to determine whether mechanistic overlap exists by administering clenbuterol to Mstn null mice. Male Mstn null and wild-type mice of similar genetic backgrounds received either 0 (control) or 20 p.p.m. clenbuterol in tap water free choice for 14 days. Several traits were measured to estimate muscle and fat growth. The Mstn null mutation resulted in increased body and empty carcass weight, increased muscle weights and decreased fat pad weights. Fat content was reduced and protein content was increased in the empty carcasses of Mstn null mice. Similarly, treatment with clenbuterol resulted in increased body and empty carcass weight, increased muscle weights and reduced fat pad weights. Fat content of empty carcasses and viscera was reduced and protein content of empty carcasses was increased with clenbuterol treatment. A significant interaction of genotype and clenbuterol treatment would indicate an altered responsiveness of Mstn null mice to clenbuterol. However, only the weight of gastrocnemius muscles exhibited a significant (P 5 0.01) interaction of genotype and clenbuterol treatment, indicating that Mstn null mice were less responsive to clenbuterol compared with wild-type mice. Thus, for all other traits, the impact of Mstn null mutation and clenbuterol treatment was completely additive. These data suggest that disruption of Mstn function does not alter the response of mice to b-adrenergic agonists.

Reductions in expression of growth regulating genes in skeletal muscle with age in wild type and myostatin null mice

“…Bicep femoris weights were similar among all treatment groups at d 21 and 42, but myostatin null muscles were heavier than wild type at d 70 (Figure  1B). These results are similar to previous reports of body and muscle weights of myostatin null mice [29,32]. …”

Effects of clenbuterol enantiomers on growth of young male rats

“…The anabolic effect on muscles might depend on various mechanisms of hypertrophy like the balance of protein synthesis and proteolysis, and might be different from the effects on bone. There were some contradictory reports that CB induced increased body weight 29,30) , and no change in heart and skeletal muscles of animals. The reason might be due to the difference in type 30,31) of animals, sex 12) , age 29) , administration method 24) , dose 8) , duration, etc.…”

“…There were some contradictory reports that CB induced increased body weight 29,30) , and no change in heart and skeletal muscles of animals. The reason might be due to the difference in type 30,31) of animals, sex 12) , age 29) , administration method 24) , dose 8) , duration, etc. 21,25) Unfortunately, in this study, we had no data on the difference in amount of physical activity or the amount of dietary intake among the 3 groups.…”

AMSTNDel273Cmutation withFGF5knockout sheep by CRISPR/Cas9 promotes skeletal muscle myofiber hyperplasia

“…MSTN is highly conserved in mammals, and mutations in the MSTN gene, either artificially or naturally, will result in increased skeletal muscle weight and produce a “double-muscle” phenotype, which has been reported in many species, including cattle, sheep, and pigs, rabbits, and humans (Grisolia et al ., 2009; Dilger et al ., 2010; Kambadur et al ., 1997). However, mutations at different loci of the MSTN often produce variety of different phenotypes, and its molecular mechanism of skeletal muscle growth and development remains controversial (Hanset and Michaux, 1985; Grobet et al ., 1997; Wegner et al ., 2000; Kambadur et al ., 1997; Marchitelli et al ., 2003).…”