title: Tanshinone IIA Attenuates Chronic Pancreatitis-Induced Pain in Rats via Downregulation of HMGB1 and TRL4 Expression in the Spinal Cord.
abstract: BACKGROUND
  Chronic pancreatitis (CP) is a long-standing inflammation of the exocrine pancreas, which typically results in severe and constant abdominal pain. Previous studies on the mechanisms underlying CP-induced pain have primarily focused on the peripheral nociceptive system. A role for a central mechanism in the mediation or modulation of abdominal pain is largely unknown. Tanshinone IIA (TSN IIA), an active component of the traditional Chinese medicine Danshen, exhibits anti-inflammatory properties via downregulation of the expression of high-mobility group protein B1 (HMGB1), a late proinflammatory cytokine. HMGB1 binds and activates toll-like receptor 4 (TLR4) to induce spinal astrocyte activation and proinflammatory cytokine release in neuropathic pain.
  
  
  OBJECTIVE
  In this study, we investigated the effect of TSN IIA on pain responses in rats with trinitrobenzene sulfonic acid (TNBS)-induced CP. The roles of central mechanisms in the mediation or modulation of CP were also investigated.
  
  
  METHODS
  A randomized, double-blind, placebo-controlled animal trial.
  
  
  METHODS
  CP was induced in rats by intrapancreatic infusion of trinitrobenzene sulfonic acid (TNBS). Pancreatic histopathological changes were characterized with semi-quantitative scores. The abdomen nociceptive behaviors were assessed with von Frey filaments. The effects of intraperitoneally administered TSN IIA on CP-induced mechanical allodynia were tested. The spinal protein expression of HMGB1 was determined by western blot. The spinal mRNA and protein expression of proinflammatory cytokines IL-1β, TNF-α, and IL-6 were determined by RT-PCR and western blot, respectively. The spinal expression of the HMGB1 receptor TRL4 and the astrocyte activation marker glial fibrillary acidic protein (GFAP) were determined by western blot or immunohistological staining after intraperitoneal injection of TSN IIA or intrathecal administration of a neutralizing anti-HMGB1 antibody.
  
  
  RESULTS
  TNBS infusion resulted in pancreatic histopathological changes of chronic pancreatitis and mechanical allodynia in rats. TSN IIA significantly attenuated TNBS-induced mechanical allodynia in a dose-dependent manner. TNBS significantly increased the spinal expression of HMGB1 and proinflammatory cytokines IL-1β, TNF-α, and IL-6. These TNBS-induced changes were significantly inhibited by TSN IIA in a dose-dependent manner. Furthermore, TSN IIA, but not the neutralizing anti-HMGB1 antibody, significantly inhibited TNBS-induced spinal TLR4 and GFAP expression.
  
  
  CONCLUSIONS
  In addition to TLR4, HMGB1 can also bind to toll-like receptor-2 (TLR2) and the receptor for advanced glycation end products (RAGE). Additional studies are warranted to ascertain whether HMGB1 contributes to CP-induced pain through activation of these receptors.
  
  
  CONCLUSIONS
  Our results suggest that spinal HMGB1 contributes to the development of CP-induced pain and can potentially be a therapeutic target. TSN IIA attenuates CP-induced pain via downregulation of spinal HMGB1 and TRL4 expression. Therefore, TSN IIA may be a potential anti-nociceptive drug for the treatment of CP-induced pain.
authors.forename: Ye-song
authors.initials: YS
authors.lastname: Wang
authors.forename: Yuan-yuan
authors.initials: YY
authors.lastname: Li
authors.forename: Li-hua
authors.initials: LH
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Kang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Zi-quan
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Kun
authors.initials: K
authors.lastname: Wang
authors.forename: Alan David
authors.initials: AD
authors.lastname: Kaye
authors.affiliation: Department of Intensive Care Unit, Second Affiliated Hospital, School of Medcine, Zhejiang University-Hangzhou 310009, Zhejiang, China; Neurointensive care unit, Second Affiliated Hospital, School of Medcine, Zhejiang University-Hangzhou 310009, Zhejiang.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000008:administration & dosage / Q000627:therapeutic use; D001572:Benzofurans / Q000008:administration & dosage / Q000627:therapeutic use*; D016207:Cytokines / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis / Q000235:genetics; D024243:HMGB1 Protein / Q000096:biosynthesis* / Q000235:genetics; D006930:Hyperalgesia / Q000188:drug therapy / Q000209:etiology; D007274:Injections, Intraperitoneal; D007278:Injections, Spinal; D009437:Neuralgia / Q000188:drug therapy / Q000235:genetics; D010146:Pain / Q000188:drug therapy* / Q000209:etiology*; D010147:Pain Measurement; D050500:Pancreatitis, Chronic / Q000139:chemically induced / Q000150:complications* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis* / Q000235:genetics; D014302:Trinitrobenzenesulfonic Acid
chemical_list: D019138:Antibodies, Blocking; D001572:Benzofurans; D016207:Cytokines; D005904:Glial Fibrillary Acidic Protein; D024243:HMGB1 Protein; C104200:Hbp1 protein, rat; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4; C530742:tashinone IIA; D014302:Trinitrobenzenesulfonic Acid