Effects of neuromuscular electrical stimulation on muscle atrophy and muscle fiber composition in quadriceps muscles of chronic obstructive pulmonary disease rats / 中华老年医学杂志

ABSTRACT

Objective To investigate the effect of neuromuscular electrical stimulation(NMES) on muscle atrophy and muscle fiber type conversion in quadriceps muscles of rats with chronic obstructive pulmonary disease(COPD).Methods Forty-eight male SPF Wistar rats were randomly divided into three groupsthe healthy control group,COPD model group and NMES treatment group,with sixteen rats in each group.Rats in the NMES treatment group were given alternating electrical stimulation at 100 Hz and 2 Hz,with each stimulation time of 30 min,7 days per week,for 4 weeks.The control group and the COPD model group were only treated with electrode sheets.After the intervention,the endurance running distance measurement,the pathological changes of rat quadriceps muscle detected by HE staining,the mRNA and protein content of MSTN,MyHC(Myosin Heavy Chain)-Ⅰ,MyHC-Ⅱ a and MyHC-Ⅱ x in quadriceps muscles determined by Realtime PCR and Western Blot were performed.Results Compared with the healthy control group,the cross-sectional area,endurance running distance and MyHC-Ⅰ mRNA and protein expressions in the quadriceps muscles were decreased[(654.7±53.7) μm2 vs.(1079.8±117.2) μm2,(396.7±42.4) m vs.(607.4 ±56.3) m,0.407 ± 0.054 vs.0.997 ± 0.069,0.884 ± 0.102 vs.1.723 ± 0.156,t =4.642,3.785,24.723 and 18.640,P =0.008,0.033,0.000 and 0.000,respectively],while MSTN,MyHC-Ⅱ a and MyHC-Ⅱx mRNA and protein expressions were increased in the COPD model group (all P ＜ 0.01)Compared with COPD model,the cross-sectional area (997.5 ± 92.4 μm2),endurance running distance(597.2±65.8 m)and the expression levels of MyHC-Ⅰ mRNA(0.884±0.097)and protein (1.534±0.182)in the quadriceps muscles were increased(t =3.734,3.602,19.988 and 13.666,P =0.035,0.043,0.000,0.000),and the mRNA and protein expression levels of MSTN,MyHC-Ⅱ a and MyHC-Ⅱ x were decreased in the NMES treatment group(all P ＜0.01).Further correlation analysis found that the protein expression of MSTN in the quadriceps muscles was negatively correlated with muscle cross-sectional area,MyHC-Ⅰ protein levels and endurance running distance(r =-0.724,0.426 and-0.536,P =0.002,0.036 and 0.007,respectively),and positively correlated with the protein expressions of MyHC-Ⅱ a and MyHC-Ⅱ x(r=0.408 and 0.392,P =0.042 and 0.048).Conclusions The expression of MSTN is increased in quadriceps muscle of COPD rats,and NMES can inhibit the expression of MSTN in quadriceps muscles.MSTN is associated with muscle atrophy and muscle fiber conversion in COPD.Inhibition of MSTN expression can improve muscle atrophy and reverse muscle fiber transformation.