title: A purine antimetabolite attenuates toll-like receptor-2, -4, and subarachnoid hemorrhage-induced brain apoptosis.
abstract: BACKGROUND
  Upregulation of high-level toll-like receptors (TLRs) is observed in the serum of animals following experimental subarachnoid hemorrhage (SAH) and is highly related to SAH-induced early brain injury (EBI). The present study was of interest to examine the effect of 6-mercaptopurine (6-MP) on alternation of TLR-2, -3, and -4 in this model.
  
  
  METHODS
  A rodent SAH model was used. Administration with 6-MP (0.5/1/2 mg/kg/d) was initiated 1 h after the induction of SAH via an osmotic minipump. Cerebral cortex was harvested to measure TLRs messenger RNA and protein (reverse transcription polymerase chain reaction [rt-PCR] and Western blot). Cerebral cortex was harvested for activated caspases (rt-PCR) measurement.
  
  
  RESULTS
  Cellular evaluation revealed increased neuronal nuclei(+) neurons with vacuolated nuclear and glial fibrillary acidic protein(+) astrocytes in the SAH group, but absent in the 6-MP treatment and healthy controls. The TLR-3 levels were not significantly increased in animals subject to SAH, compared with the controls (no SAH). The levels of TLR-2 and -4 in the SAH only and SAH plus vehicle groups were significantly elevated (P < 0.01), and treatment with 6-MP reduced TLR-2, -3 (at 2 mg/kg), and -4 (dose-dependently) protein expression following SAH. Likewise, the TLR-4 messenger RNA levels were also significantly reduced in the 6-MP (at 1 mg/kg and 2 mg/kg) groups. Cleaved caspase-3 and caspase-9a were reduced at 2-mg/kg 6-MP treatment group.
  
  
  CONCLUSIONS
  These results show that 6-MP attenuates the expression of TLR-2, -4, especially TLR-4, which play an antiapoptotic effect on SAH-induced EBI. This finding supported that through modulating TLRs, 6-MP can attenuate SAH-induced EBI. Those results offer credit to the neuroprotective effect of 6-MP.
authors.affiliation: Department of Surgery, Faculty of Medicine, School of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan, Republic of China; Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan, Republic of China; Department of Surgery, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung City, Taiwan, Republic of China. Electronic address: changchihzen2002@yahoo.com.tw.
authors.forename: Chih-Zen
authors.initials: CZ
authors.lastname: Chang
authors.affiliation: Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan, Republic of China.
authors.forename: Shu-Chuan
authors.initials: SC
authors.lastname: Wu
authors.affiliation: Department of Surgery, Faculty of Medicine, School of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan, Republic of China; Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan, Republic of China.
authors.forename: Aij-Lie
authors.initials: AL
authors.lastname: Kwan
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear; D000963:Antimetabolites / Q000494:pharmacology / Q000627:therapeutic use*; D001930:Brain Injuries / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D008297:Male; D015122:Mercaptopurine / Q000494:pharmacology / Q000627:therapeutic use*; D009419:Nerve Tissue Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*
chemical_list: D034961:Antigens, Nuclear; D000963:Antimetabolites; D016207:Cytokines; D009419:Nerve Tissue Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C546339:Rbfox3 protein, rat; D051193:Toll-Like Receptors; D015122:Mercaptopurine; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9
keywords: 6-Mercaptopurine; Cysteine requiring aspartate proteases; Early brain injury; Subarachnoid hemorrhage; Toll-like receptors