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Downregulation of electroacupuncture at ST36 on TNF-α in rats with ulcerative colitis


   AIM:To investigate the regulatory effect of electroacupuncture(EA) at Zusanli (ST36) on tumor necrosis factor-alpha (TNF-α) in rats with ulcerative colitis (UC),and further elucidatethe therapeutic mechanism of EA on UC.METHODS:Thirty-two male Sprague-Dawley (SD) rats wererandomly divided into four groups (n=8):normal controlgroup,UC control group,UC+ST36 group and UC+non-acupoint group.A solution containing ethanol and 2,4,6-trinitrobenzenesulfonic acid (TNBS) was instilled into thedistal colon in the rat (at a dose of 100 mg/kg) to set up UCrat model.Rats in wakefulness state of UC+ST36 group werestimulated at ST36 by EA once a day,while those of UC+non-acupoint group were done at 0.5 cm beside ST36.After 10d treatment,all rats were sacrificed simultaneously.Colonmusocal inflammation and damage were assessed bymeasuring colon mass,morphologic damage score,colonicmyeloperoxidase enzyme (MPO) activity,serum TNF-α andcolonic TNF-α mRNA level.Morphologic damage score wasexamined under stereomicroscope.Colonic MPO activity wasmeasured by spectrophotometer method.Serum TNF-αconcentration was determined by radioimmunoassay (RIA).Colonic TNF-α mRNA expression level was analyzed bysemiquantitative reverse transcription polymerase chainreaction (RT-PCR).RESULTS:Ratio of colonic mass/body mass (m_C/m_B) andactivity of colonic MPO (μkat/g tissue) markedly increased(8.5±2.6 vs 2.5±0.4;145±25 vs 24±8,P<0.01 vs normalcontrol group).Compared with normal control rats,serumTNF-α and colonic TNF-α mRNA level in UC control groupwere increased 2.5 fold (2 278±170 vs 894±248,P<0.01)and 4.3 fold (0.98±0.11 vs 0.23±0.11,P<0.01)respectively.After EA at ST36,m_C/m_B and MPO activitywere reduced significantly (5.3±2.0 vs 8.5±2.6;104±36 vs145±25,P<0.01,0.05) compared with those of UC controlgroup.Serum TNF-α and colonic TNF-α mRNA level wereinhibited by EA stimulation at ST36 (P<0.01).Theinhibitory rate was 16% and 44% respectively.Morphologic damage score was also increased markedlyin rat with UC (P<0.01),whereas it was decreased by EAat ST36 (P<0.05).There was no significant differencebetween UC control group and UC+EA at non-acupoint (P>0.05).Furthermore,these parameters were highlycorrelated with each other (P<0.01).CONCLUSION:Serum TNF-α concentration and colonicTNF-α mRNA expression level are increased significantly inUC rats in correlation with the severity of disease.It indicatesthat TNF-α is closely involved in the immune abnormalitiesand inflammatory responses in UC.EA at ST36 hastherapeutic effect on UC by downregulating serum TNF-αand colonic TNF-α mRNA expression.High levels of TNF-αand its corresponding mRNA expression seem to beimplicated in the pathogenesis of UC.……