title: Effect of glycyrrhizin on traumatic brain injury in rats and its mechanism.
abstract: OBJECTIVE
  To investigate the neuroprotective effects of glycyrrhizin (Gly) as well as its effect on expression of high-mobility group box 1 (HMGB1) in rats after traumatic brain injury (TBI).
  
  
  METHODS
  Male Sprague-Dawley rats were randomly divided into three groups: sham group, TBI group, and TBI+Gly group (n=36 per group). Rat TBI model was made by using the modified Feeney's method. In TBI+Gly group, Gly was administered intravenously at a dosage of 10 mg/kg 30 min after TBI. At 24 h after TBI, motor function and brain water content were evaluated. Meanwhile, HMGB1/HMGB1 receptors including toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE)/nuclear factor-κB(NF-κB) signaling pathway and inflammatory cytokines in the injured brain tissues were detected using quantitative real-time polymerase chain reaction, western blot, electrophoretic mobility shift assay and enzyme-linked immunosorbent assay. Furthermore, HMGB1, RAGE and TLR4 immunohistochemistry and apoptosis were analyzed.
  
  
  RESULTS
  Beam walking performance impairment and brain edema were significantly reduced in TBI+Gly group compared with TBI group; meanwhile, the over-expressions of HMGB1/HMGB1 receptors (TLR4 and RAGE)/NF-κB DNA-binding activity and inflammatory cytokines were inhibited. The percentages of HMGB1, RAGE and TLR4-positive cells and apoptotic cells were respectively 58.37% ± 5.06%, 54.15% ± 4.65%, 65.50% ± 4.83%, 52.02% ± 4.63% in TBI group and 39.99% ± 4.99%, 34.87% ± 5.02%, 43.33% ± 4.54%, 37.84% ± 5.16% in TBI+Gly group (all P<0.01 compared with TBI group).
  
  
  CONCLUSIONS
  Gly can reduce secondary brain injury and improve outcomes in rat following TBI by down-regulation of HMGB1/HMGB1 receptors (TLR4 and RAGE)/NF-κB-mediated inflammatory responses in the injured rat brain.
authors: Department of Neurosurgery, Jiangning Hospital Affiliated to Nanjing Medical University, Nanjing 211100, China.
authors: Xiang-Jin
authors: XJ
authors: Gu
authors: Jin
authors: J
authors: Xu
authors: Ban-You
authors: BY
authors: Ma
authors: Gong
authors: G
authors: Chen
authors: Pei-Yuan
authors: PY
authors: Gu
authors: Dong
authors: D
authors: Wei
authors: Wei-Xing
authors: WX
authors: Hu
mesh_terms: D000818:Animals; D001930:Brain Injuries / Q000188:drug therapy*; D019695:Glycyrrhizic Acid / Q000494:pharmacology* / Q000627:therapeutic use*; D024243:HMGB1 Protein / Q000378:metabolism*; D008297:Male; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D024243:HMGB1 Protein; D018696:Neuroprotective Agents; D019695:Glycyrrhizic Acid