<p style="text-align: center;">HU Li, WEN Peitong, ZHANGWeibo, GAO Yuan, SHOUYin, WANG Xiaonan², and XU Ping¹</p><p style="text-align: center;">(1 Acumox&amp;Tuina College of Shanghai University of Traditional Chinese Medicine, Shanghai 201203; 2 Department of Medicine of Emory University, Atlanta, GA 30322)</p><p style="text-align: justify;"><strong>Abstract</strong>:<strong> Background</strong>: 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,&nbsp; and&nbsp; the&nbsp; degree&nbsp; of&nbsp; muscular&nbsp; atrophy&nbsp; has&nbsp; become&nbsp; an&nbsp; important&nbsp; predictor&nbsp; of&nbsp; mortality&nbsp; rate.&nbsp; In Traditional&nbsp; Chinese&nbsp; Medicine(TCM),&nbsp; skeletal&nbsp; muscle&nbsp; belongs&nbsp; to&nbsp; &quot;the&nbsp; muscle&nbsp; meridian&quot;&nbsp; (Jing&nbsp; Jin).The symptoms of muscle movement and physical activity dysfunction, during the age-related skeletal muscle atrophy, accord with &quot;Wei Syndrome&quot; in TCM.Based on TCM theory of “treatment for flaccidity aiming at Yang Ming meridian” and&quot;the kidney dominating bone &quot;, we hypothesized that combined togetherZusanli and&nbsp; Shenshucould&nbsp; attenuate&nbsp; aging-induced&nbsp; skeletal&nbsp; muscle&nbsp; atrophy .Objective:&nbsp; Based&nbsp; on&nbsp; TGF-β/Smad signaling pathway to explore the mechanism of low frequency electroacupuncture on aging rats skeletal muscle&nbsp; atrophy,&nbsp; to&nbsp; provide&nbsp; the&nbsp; basis&nbsp; for&nbsp; attenuating&nbsp; age-related&nbsp; skeletal&nbsp; muscle&nbsp; atrophy.&nbsp; <strong>Methods</strong>:The aging rats of 18 months(YA), 20 months (EA) and 22 months(JA) were used in this study. Two acupoints, Shenshu(BL23)&nbsp; and&nbsp; Zusanli(ST36),&nbsp; were&nbsp; selected.&nbsp; The&nbsp; needles&nbsp; were&nbsp; connected&nbsp; into&nbsp; G6805-2&nbsp; electronic acupuncture&nbsp; instrument&nbsp; using&nbsp; consistent&nbsp; pulse,electric&nbsp; frequency&nbsp; 2Hz,voltage&nbsp; 2 ～ 4V,&nbsp; electric&nbsp; current 1mA～3mA. The stimulation intensity was suitable for rats with slight limb jitter. The treatment was 15 minutes&nbsp; each&nbsp; time&nbsp; on&nbsp; alternate&nbsp; days&nbsp; with&nbsp; one&nbsp; week&nbsp; of&nbsp; rest&nbsp; after&nbsp; three&nbsp; weeks&nbsp; treatment&nbsp; continually. Treatment&nbsp; durations&nbsp; for&nbsp; each&nbsp; group&nbsp; were&nbsp; YA(12&nbsp; -18&nbsp; months)，EA(12&nbsp; -20&nbsp; months)，JA(12-22&nbsp; months).Skeletal&nbsp; muscles&nbsp; of&nbsp; gastrocnemius&nbsp; and&nbsp; soleus,SOD&nbsp; and&nbsp; MDA&nbsp; in&nbsp; serum&nbsp; and&nbsp; HE&nbsp; staining&nbsp; for&nbsp; soleus&nbsp; 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. <strong>Results:</strong> (1)Compared with the controlgroup, the weight&nbsp; 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&nbsp; months,&nbsp; while&nbsp; acupuncture&nbsp; treatment&nbsp; could&nbsp; effectively&nbsp; reverse&nbsp; this&nbsp; tendency&nbsp; (P&lt;&nbsp; 0.05).&nbsp; (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),&nbsp; acupuncture treatment increased&nbsp; the&nbsp; protein&nbsp; expressionsof&nbsp; TGF-β/Smadsignaling&nbsp; pathway(TGF-β,&nbsp; Smad2,&nbsp; p-smad2,&nbsp; Smad3,&nbsp; psmad3,&nbsp; myostatin),&nbsp; while&nbsp; compared&nbsp; with&nbsp; 22&nbsp; months&nbsp; control&nbsp; group(JA),&nbsp; acupuncture&nbsp; treatmentdecreasedthe&nbsp; protein&nbsp; expression&nbsp; significantly&nbsp; (P&lt;&nbsp; 0.05).Conclusions:&nbsp; We&nbsp; hold&nbsp; that&nbsp; electric&nbsp; acupuncture could&nbsp; attenuate&nbsp; aging-related&nbsp; rat&nbsp; skeletal&nbsp; muscle&nbsp; atrophy&nbsp; by&nbsp; promoting&nbsp; muscle&nbsp; regeneration&nbsp; and/or reducing skeletal muscle fibrosis in the later stage.</p><p style="text-align: justify;"><strong>Key words</strong>: Skeletal muscle atrophy, Age-related, Skeletal muscle satellite cell, TGF-β/Smad</p><p><br/></p>