title: Fractionated radiation-induced acute encephalopathy in a young rat model: cognitive dysfunction and histologic findings.
abstract: OBJECTIVE
  Radiation-induced cognitive dysfunction is a common and serious complication after radiation therapy of brain tumor, yet knowledge of its mechanism is poorly understood. The aim of this study was to establish a young rat model for acute radiation encephalopathy, at both cognitive and pathologic levels, induced by fractionated irradiation.
  
  
  METHODS
  Four-week-old male rats were randomized into sham (0 Gy) and 2 experimental groups receiving fractionated irradiation of 5 Gy/day, 5 days/week, with total doses of 20 and 40 Gy, respectively. Cognition, BBB integrity, and potential astrogliosis were evaluated at 0, 4, 8, and 12 weeks' postirradiation.
  
  
  RESULTS
  Twenty-Gy irradiation led to transient cognitive impairment only at 4 weeks' postirradiation. Forty-Gy irradiation induced cognitive impairment at both 4 and 8 weeks' postirradiation, which was more severe than that induced by 20 Gy. Cognitive impairment was accompanied by a transient increase in BWC only at 4 weeks for the 40-Gy group. Disrupted BBB permeability was detected at 4 and 8 weeks' postirradiation for the 20-Gy group, and at 4, 8, and 12 weeks' postirradiation for 40-Gy group, respectively. Increased astrogliosis in the hippocampus could be detected at 4 weeks' postirradiation for 40-Gy group.
  
  
  CONCLUSIONS
  Fractionated irradiation in this experiment could induce acute brain injury, leading to cognitive impairment in young rats. BBB disruption might be a sensitive index for acute radiation encephalopathy. In addition, reactive astrogliosis might play an important role in this process. The present model, especially the 40-Gy irradiation group, is useful for basic and therapeutic studies of acute radiation encephalopathy.
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: H
authors.initials: H
authors.lastname: Zhou
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Zhou
authors.forename: Z
authors.initials: Z
authors.lastname: Zhao
authors.forename: S
authors.initials: S
authors.lastname: Xiao
authors.forename: E
authors.initials: E
authors.lastname: Tao
authors.forename: W Z
authors.initials: WZ
authors.lastname: Suo
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology / Q000528:radiation effects; D001927:Brain Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D003071:Cognition / Q000528:radiation effects*; D003072:Cognition Disorders / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley