Dantrolene Downregulates the Gene Expression and Activity of the Ubiquitin–Proteasome Proteolytic Pathway in Septic Skeletal Muscle

Abstract

Background. In previous studies, dantrolene prevented sepsis-induced muscle proteolysis, but the influence of dantrolene on the expression and activity of the ubiquitin–proteasome proteolytic pathway is not known. In addition, the role of glucocorticoids in the anabolic effect of dantrolene is not well understood. Methods. Sepsis was induced in rats by cecal ligation and puncture (CLP). Other rats underwent sham-operation. Groups of rats were treated with dantrolene (10 mg/kg) administered 2 h before and 8 h after sham-operation or CLP. Sixteen hours after sham-operation or CLP, mRNA levels for ubiquitin, the ubiquitin ligase E3α, and the 20S proteasome subunit C3 were determined by dot-blot analysis. In additional experiments, the effect of dantrolene on protein degradation was tested in L6 myotubes cultured in the absence or presence of dexamethasone. Results. Treatment of rats with dantrolene prevented the sepsis-induced increase in mRNA levels for ubiquitin, the ubiquitin ligase E3α, and the 20S proteasome subunit C3. In additional experiments, treatment of cultured myotubes with dantrolene reduced protein degradation in both the absence and the presence of dexamethasone. Conclusions. The results suggest that dantrolene can prevent sepsis-induced activation of the ubiquitin–proteasome proteolytic pathway in skeletal muscle and that dantrolene reduces muscle protein degradation independent of glucocorticoids.