ABSTRACT
Objective:To explore the role of microRNA-133a (miR-133a) and silent mating information regulation 2 homolog 1 (SIRT1) in the effects of electroacupuncture on persons with disuse muscular atrophy.Methods:Thirty C57BL/6 mice were randomly divided into a control group, an experimental control group and an experimental group, each of 10. Disuse muscular atrophy was induced in the mice of the experimental and experimental control groups using tail suspension. The mice in the electroacupuncture group were given 15 minutes of electroacupuncture over the Yanglingquan and Zusanli points every day for 14 days. Wet weight ratio and the cross-sectional area of the gastrocnemius and soleus were tracked, and the structure of the mitochondria in the skeletal muscles was observed using a transmission electron microscope. The protein expressions of SIRT1, peroxisome proliferator-activated receptor γ coactivator-1a (PGC-1a), nicotinamide phosphoribosyl transferase (NAMPT), adenosine 5-monophosphate-activated protein kinase-a (AMPK-a) and phospho-AMPK-a (P-AMPK-a) were detected using western blotting. The expressions of the muscle atrophy F-box (Atrogin-1), muscle ring finger1 (MuRF1), miR-133a, SIRT1, paired box gene 7 (Pax7), myogenic determination (MyoD) and myogenin (MyoG) genes were detected through polymerase chain reactions. The concentration of Niacylamide adenine dinucleotide (NAD+ ) and the ratio of NAD+ to reduced nicotinamide adenine dinucleotide were also measured.Results:Compared with the experimental control group, the average wet weight increased by 21% and the cross-sectional area of the soleus increased by 30% in the experimental group. The average wet weight of the gastrocnemius increased by 5% and the area by 17%. The average expressions of Atrogin-1, MuRF1, SIRT1, PGC-1a and NAMPT, the concentration of NAD+ , as well as the average value of P-AMPK-a/AMPK-a and NAD+ /NADH were significantly lower in the experimental group than in the experimental control group, while the average expression of miR-133a in the experimental group was significantly (163%) higher. The average expressions of Pax7 and MyoD were significantly up-regulated in the experimental control group compared with the other two groups, while MyoG was highly expressed in the experimental group compared with the other 2 groups.Conclusions:The SIRT1 pathway is one of the reflexive protective mechanisms that mediate in the natural recovery of skeletal muscles. Electroacupuncture enhances myoblast differentiation, improves energy metabolism in the mitochondria, and thus promotes recovery from disuse muscular atrophy.
ABSTRACT
Objective:To observe the effect of low-intensity pulsed ultrasound (LIPUS) at different intensities on the expression of adiponectin and its receptors in C2C12 myoblasts, and to explore the potential mechanism by which LIPUS promotes the differentiation of C2C12 myoblasts.Methods:C2C12 myoblasts cultured in vitro were randomly divided into a control group and U 0.1, U 0.3 and U 0.5 groups. The control group received sham LIPUS exposure, while the U 0.1, U 0.3 and U 0.5 groups were exposed to LIPUS at intensities of 0.1W/cm 2, 0.3W/cm 2 or 0.5W/cm 2 respectively, and 1MHz for 5 min daily for 5 days. Cell viability was measured using CCK-8 assays. Fluorescence quantitative reverse transcription-polymerase chain reactions were used to detect the mRNA expression of adiponectin, adiponectin receptor 1 (adipoR1) and T-cadherin in the cells. Western blotting was employed to assess the protein expression of adiponectin, adipoR1, T-cadherin, adenosine monophosphate activated protein kinase (AMPK), activated phosphorylated adenylate-activated protein kinase (P-AMPK), embryonic myosin heavy chain (eMHC) and myogenin (MYOG). The differentiation ability of the 4 groups was measured using cell immunofluorescence chemistry. Results:After the intervention the cell viability in the U 0.1, U 0.3 and U 0.5 groups was significantly higher than in the control group. Compared with the control group, the average mRNA expression of adiponectin and the receptors of adipoR1 and T-cadherin were up-regulated significantly in the U 0.3 and U 0.5 groups. The average adiponectin, adipoR1 and T-cadherin protein expressions, and the AMPK phosphorylation level in the U 0.3 and U 0.5 groups had increased significantly compared with the control group, but all were significantly lower than in the U 0.3 group. The average protein expression of eMHC and MYOG, and the C2C12 myoblast fusion indices of the U 0.3 and U 0.5 groups were significantly higher the control group′s averages. Conclusions:LIPUS can promote the differentiation of C2C12 myoblasts. It is most effective at 0.3W/cm 2, administered for 5min/d at 1MHz with a 20% duty cycle. Its regulatory mechanism may be related to up-regulation of the expression of adiponectin, the adipoR1 and T-cadherin receptors, and the activation of AMPK phosphorylation in C2C12 myoblasts.