Objective To explore the effect of electroacupuncture(EA)on amyotrophia and expression of paired box7(Pax7)

myogenic differentiation antigen-1(Myod1)

myogenin(Myog)

myosin heavy chain-Ⅱa(Myh2)

myosin heavy chain-Ⅱx(Myh1)and myosin heavy chain-Ⅰ(Myh7)of denervated gastrocnemius in rats with chronic constriction injury(CCI)of the right sciatic nerve

so as to explore its mechanisms underlying postponing development of amyotrophia.Methods Sixty-six SD adult male rats were randomly divided into sham operation(sham)group(n=24)

model group(n=24)and EA group(n=18).The denervated muscle(gastrocnemius)atrophy model was established by CCI of the right sciatic nerve.EA(2 Hz

1.0 mA)was applied to the right"Zusanli"(ST36)and"Huantiao"(GB30)for 10 min

once a day

six times a week and for 1

2 and 4 weeks

respectively.After complete dissection of bilateral gastrocnemius muscles

their wet weight levels were measured and the ratio of wet weight(=that of the operation side/that of the non-operation side)was calculated

and the cross-sectional area(CSA)and diameter of the gastronemius were detected after fixation in 4%paraformaldehyde

sectioning

and H.E.staining.The expression levels of Pax7

Myod1

Myog

Myh2

Myh1 and Myh7 mRNAs in the gastrocnemius tissue after 3 weeks of modeling were detected with quantitative real time-PCR(qPCR).Results After 1 week of modeling

the ratios of wet weight of gastrocnemius and the CSA and fiber diameter at the 2 nd

3 rd and 5 th week were significantly smaller in the model group than in the sham group(P<0.05).The expression levels of Myod1 and Myog mRNAs were significantly up-regulated(P<0.01)

and those of Myh2

Myh1 and Myh7 considerably down-regulated in the model group compared with the sham group(P<0.05

P<0.01).No significant changes were found in the expression levels of Pax7 mRNA after modeling and EA intervention(P>0.05).Following EA intervention

the CSA and diameterof the gastronemius were obviously increased(P<0.05)

and the expression levels of Myod1

Myog and Myh7 further markedly or remarkably up-regulated in comparison with the model group(P<0.05

P<0.01).No significant changes were found in the ratio of wet weight of gastrocnemius at the 3 time-points

and the expression levels of Myh2 mRNA and Myh1 mRNA in the EA group relevant to the model group after 3 weeks of modeling(P>0.05).Conclusion EA treatment may delay gastrocnemius atrophy in CCI rats

which is possibly associated with its effects in up-regulating the expression of Myod1

Myog and Myh7 mRNAs to control the differentiation of the satellite cells and the muscle fiber type transformation.