title: [p35 and p25 expressions and Cdk5 kinase activity in primary cultured rat hippocampal neurons with X-ray exposure].
abstract: OBJECTIVE
  To study the expressions of p35 and p25 and Cdk5 kinase activity in cultured rats hippocampal neurons following X-ray exposure to provide experimental evidence for prevention and treatment of radiation encephalopathy.
  
  
  METHODS
  The hippocampal neurons cultured for 12 days were subjected to a single-dose X-ray exposure of 30 Gy. Western blotting was used to detect the p35 and p25 protein levels, and the effect of pretreatment with roscovitine, a Cdk5 inhibitor, on the apoptosis of the hippocampal neurons following the exposure was examined with 4',6-diamidino-2-phenylindole (DAPI) staining.
  
  
  RESULTS
  The protein level of p35 increased significantly 3.5 and 4 h after the irradiation by 1.51-/+0.13 and 1.45-/+0.14 folds in comparison with the control level, respectively (P<0.01), and the p25 level increased significantly 6 h after irradiation by 1.62-/+0.28 folds (P<0.05). Nuclear condensation occurred in (24.8-/+3.97)% of the neurons 24 h after 30 Gy X-ray exposure, a rate significantly higher than that in the nonexposed cells [(1.82-/+1.08)%, P<0.01) and that in roscovitine-pretreated neurons [(7.74-/+2.27)%, P<0.01).
  
  
  CONCLUSIONS
  X-ray exposure activates Cdk5 by increasing the p35 and p25 expressions in rat hippocampal neurons, and inhibition of Cdk5 activity with roscovitine can significantly protect the neurons from apoptosis.
authors.affiliation: Department of Radiotherapy, Nanfang Hospital, Southern Medical University, Guangzhou, China. goodthea@163.com
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Han
authors.forename: Ai-Min
authors.initials: AM
authors.lastname: Sun
authors.forename: Que-Ling
authors.initials: QL
authors.lastname: Liu
authors.forename: Long-Hua
authors.initials: LH
authors.lastname: Chen
authors.forename: Ya-Wei
authors.initials: YW
authors.lastname: Yuan
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D051360:Cyclin-Dependent Kinase 5 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006624:Hippocampus / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D009474:Neurons / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C492235:Cdk5r1 protein, rat; D010770:Phosphotransferases; D051360:Cyclin-Dependent Kinase 5; C495907:Cdk5 protein, rat