HU Li, WEN Peitong, ZHANGWeibo, GAO Yuan, SHOUYin, WANG Xiaonan², and XU Ping ¹

(1 Acumox&Tuina College of Shanghai University of Traditional Chinese Medicine, Shanghai 201203; 2 Department of Medicine of Emory University, Atlanta, GA 30322)

Abstract: Background: At present,all countries in the world are facing a serious ageing of population. In the course of aging, muscle atrophy, fibrosis and fat deposition are the main causes of the decrease of muscle function,  and  the  degree  of  muscular  atrophy  has  become  an  important  predictor  of  mortality  rate.  In Traditional  Chinese  Medicine(TCM),  skeletal  muscle  belongs  to  "the  muscle  meridian"  (Jing  Jin).The symptoms of muscle movement and physical activity dysfunction, during the age-related skeletal muscle atrophy, accord with "Wei Syndrome" in TCM.Based on TCM theory of “treatment for flaccidity aiming at Yang Ming meridian” and"the kidney dominating bone ", we hypothesized that combined togetherZusanli and  Shenshucould  attenuate  aging-induced  skeletal  muscle  atrophy .Objective:  Based  on  TGF-β/Smad signaling pathway to explore the mechanism of low frequency electroacupuncture on aging rats skeletal muscle  atrophy,  to  provide  the  basis  for  attenuating  age-related  skeletal  muscle  atrophy.  Methods:The aging rats of 18 months(YA), 20 months (EA) and 22 months(JA) were used in this study. Two acupoints, Shenshu(BL23)  and  Zusanli(ST36),  were  selected.  The  needles  were  connected  into  G6805-2  electronic acupuncture  instrument  using  consistent  pulse,electric  frequency  2Hz,voltage  2 ～ 4V,  electric  current 1mA～3mA. The stimulation intensity was suitable for rats with slight limb jitter. The treatment was 15 minutes  each  time  on  alternate  days  with  one  week  of  rest  after  three  weeks  treatment  continually. Treatment  durations  for  each  group  were  YA(12  -18  months)，EA(12  -20  months)，JA(12-22  months).Skeletal  muscles  of  gastrocnemius  and  soleus,SOD  and  MDA  in  serum  and  HE  staining  for  soleus  were measured respectively. Protein expressions, including TGF-β/P-smad2/P-smad3/Smad2-3/Myostatin, which related to skeletal muscle fibrosis signaling proteins and MyoD /Myogenin/eMyHC, which related to muscle myogenesis were measured by Western blot. T-test and ANOVA were used for results statistics. Results: (1)Compared with the controlgroup, the weight  of the rats for the 18 months, 20 months and 22 months decreased after the acupuncture treatment but the wet weight of the soleus and gastrocnemius increased. (2)The serum expression of SOD decreased significantly and the MDA expression increased significantlyfor different  months,  while  acupuncture  treatment  could  effectively  reverse  this  tendency  (P<  0.05).  (3)In control groupof different months, there were signs of aging, which showed that the muscle fibers were more loosely arranged, and the fibroid was round, and the nuclei were more central. After the acupuncture treatment, the muscle fibers were more closely aligned, and the circular fibrosis and nucleus centralization decreased. (4) Compared with 18 months(YC) and 20 months of control groups(EC),  acupuncture treatment increased  the  protein  expressionsof  TGF-β/Smadsignaling  pathway(TGF-β,  Smad2,  p-smad2,  Smad3,  psmad3,  myostatin),  while  compared  with  22  months  control  group(JA),  acupuncture  treatmentdecreasedthe  protein  expression  significantly  (P<  0.05).Conclusions:  We  hold  that  electric  acupuncture could  attenuate  aging-related  rat  skeletal  muscle  atrophy  by  promoting  muscle  regeneration  and/or reducing skeletal muscle fibrosis in the later stage.

Key words: Skeletal muscle atrophy, Age-related, Skeletal muscle satellite cell, TGF-β/Smad