title: Impaired integrity of DNA after recovery from inflammation causes persistent dysfunction of colonic smooth muscle.
abstract: OBJECTIVE
  Patients with inflammatory bowel disease who are in remission and those who developed irritable bowel syndrome after enteric infection continue to have symptoms of diarrhea or constipation in the absence of overt inflammation, indicating motility dysfunction. We investigated whether oxidative stress during inflammation impairs integrity of the promoter of Cacna1c, which encodes the pore-forming α1C subunit of Ca(v)1.2b calcium channels.
  
  
  METHODS
  We used long-extension polymerase chain reaction to evaluate DNA integrity in tissues from distal colons of rats; trinitrobenzene sulfonic acid was used to induce inflammation.
  
  
  RESULTS
  The H2O2 increased in the muscularis externa 1-7 days after inflammation was induced with trinitrobenzene sulfonic acid. The oxidative stress significantly impaired DNA integrity in 2 specific segments of the Cacna1c promoter: -506 to -260 and -2193 to -1542. The impairment peaked at day 3 and recovered partially by day 7 after induction of inflammation; expression of the products of Cacna1c followed a similar time course. Oxidative stress suppressed the expression of nuclear factor-erythroid-2-related factor 2 (Nrf2), an important regulator of anti-oxidant proteins. Intraperitoneal administration of sulforaphane significantly reversed the suppression of Nrf2, oxidative damage in the promoter of Cacna1c, and suppression of Cacna1c on day 7 of inflammation. The inflammation subsided completely by 56 days after inflammation was induced; however, impairment of DNA integrity, expression of Nrf2 and Cacna1c, and smooth muscle reactivity to acetylcholine remained suppressed at this time point.
  
  
  CONCLUSIONS
  Oxidative stress during inflammation impairs the integrity of the promoter of Cacna1c; impairment persists partially after inflammation has subsided. Reduced transcription of Cacna1c contributes to smooth muscle dysfunction in the absence of inflammation.
authors: Enteric Neuromuscular Disorders and Visceral Pain Center, Division of Gastroenterology, Department of Internal Medicine, The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-1063, USA.
authors: Kuicheon
authors: K
authors: Choi
authors: Jinghong
authors: J
authors: Chen
authors: Sankar
authors: S
authors: Mitra
authors: Sushil K
authors: SK
authors: Sarna
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D020746:Calcium Channels, L-Type / Q000235:genetics* / Q000378:metabolism; D003092:Colitis / Q000139:chemically induced / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology*; D003106:Colon / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D004249:DNA Damage; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005769:Gastrointestinal Motility / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D015212:Inflammatory Bowel Diseases / Q000139:chemically induced / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism; D017879:Isothiocyanates; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D051381:Rats; D013454:Sulfoxides; D013861:Thiocyanates / Q000494:pharmacology; D013997:Time Factors; D014302:Trinitrobenzenesulfonic Acid
chemical_list: C504728:Cacna1c protein, rat; D020746:Calcium Channels, L-Type; D017879:Isothiocyanates; D051267:NF-E2-Related Factor 2; C495637:Nfe2l2 protein, rat; D013454:Sulfoxides; D013861:Thiocyanates; D014302:Trinitrobenzenesulfonic Acid; D006861:Hydrogen Peroxide; C016766:sulforaphane; D000109:Acetylcholine