Muscle Myostatin mRNA Expression Research Articles

Resistance Exercise-Induced Increases in Muscle Myostatin mRNA and Protein Expression Are Subsequently Decreased in Circulation in the Presence of Increased Levels of the Extracellular Matrix Stabilizing Protein Decorin.

Resistance exercise (RE) activates cell signaling pathways associated with myostatin. Decorin is located in the extracellular matrix (ECM) and can block the inhibitory effect of myostatin. This study sought to determine the impact of low-load (LL) and high-load (HL) RE on myostatin mRNA and protein expression along with changes in muscle decorin and circulating follistatin. Ten resistance-trained men performed a LL (50% 1RM) and HL (80% 1RM) RE session using the angled leg press and leg extension with load and volume equated. Venous blood samples and muscle biopsies were obtained prior to and at 3h and 24h following each RE session. Muscle myostatin mRNA expression was increased at 24h post-exercise (p = 0.032) in LL and at 3h (p = 0.044) and 24h (p = 0.003) post-exercise in HL. Muscle decorin was increased at 24h post-exercise (p < 0.001) in LL and HL; however, muscle myostatin was increased at 24h post-exercise (p < 0.001) only in HL. For muscle Smad 2/3, no significant differences were observed (p > 0.05). Serum follistatin was increased and myostatin decreased at 24h post-exercise (p < 0.001) in LL and HL. Muscle myostatin gene and protein expression increased in response to HL RE. However, serum myostatin was decreased in the presence of increases in decorin in muscle and follistatin in circulation. Therefore, our data suggest a possible mechanism may exist where decorin within the ECM is able to bind to, and decrease, myostatin that might otherwise enter the circulation for activin IIB (ACTIIB) receptor binding and subsequent canonical signaling through Smad 2/3.

Neuromuscular electrical stimulation prevents muscle disuse atrophy during leg immobilization in humans

Short periods of muscle disuse, due to illness or injury, result in substantial skeletal muscle atrophy. Recently, we have shown that a single session of neuromuscular electrical stimulation (NMES) increases muscle protein synthesis rates. The aim was to investigate the capacity for daily NMES to attenuate muscle atrophy during short-term muscle disuse. Twenty-four healthy, young (23 ± 1 year) males participated in the present study. Volunteers were subjected to 5 days of one-legged knee immobilization with (NMES; n = 12) or without (CON; n = 12) supervised NMES sessions (40-min sessions, twice daily). Two days prior to and immediately after the immobilization period, CT scans and single-leg one-repetition maximum (1RM) strength tests were performed to assess quadriceps muscle cross-sectional area (CSA) and leg muscle strength respectively. Furthermore, muscle biopsies were taken to assess muscle fibre CSA, satellite cell content and mRNA and protein expression of selected genes. In CON, immobilization reduced quadriceps CSA by 3.5 ± 0.5% (P < 0.0001) and muscle strength by 9 ± 2% (P < 0.05). In contrast, no significant muscle loss was detected following immobilization in NMES although strength declined by 7 ± 3% (P < 0.05). Muscle MAFbx and MuRF1 mRNA expression increased following immobilization in CON (P < 0.001 and P = 0.07 respectively), whereas levels either declined (P < 0.01) or did not change in NMES, respectively. Immobilization led to an increase in muscle myostatin mRNA expression in CON (P < 0.05), but remained unchanged in NMES. During short-term disuse, NMES represents an effective interventional strategy to prevent the loss of muscle mass, but it does not allow preservation of muscle strength. NMES during disuse may be of important clinical relevance in both health and disease.

A step towards underpinning the molecular signalling events regulating muscle protein loss in critically ill patients

A step towards underpinning the molecular signalling events regulating muscle protein loss in critically ill patients