title: Impact of Preoperative Environmental Enrichment on Prevention of Development of Cognitive Impairment following Abdominal Surgery in a Rat Model.
abstract: BACKGROUND
  Sustained neuroinflammation may contribute to the pathogenesis of postoperative cognitive dysfunction (POCD). Here, the authors evaluated the preventive effect of preoperative environmental enrichment (PEE) on the development of neuroinflammation and concomitant POCD in a rat abdominal surgery model.
  
  
  METHODS
  Young and aged rats were assigned to one of four groups using a 2 × 2 experimental design: PEE versus sedentary condition for 14 days, by abdominal surgery versus anesthesia alone (n = 8 in each group). After a 7-day postsurgical recovery period, cognitive function was assessed using a novel object recognition test, followed by measurement of hippocampal levels of proinflammatory cytokines. Under identical conditions, microglia were isolated from the hippocampus for assessment of cytokine response to lipopolysaccharide.
  
  
  RESULTS
  In the sedentary group, aged, but not young, rats receiving surgery showed memory deficits (novel object preference during testing phase of 54.6 ± 7.8% vs. 76.9 ± 11.3% in nonsurgery group, P < 0.05) and increased hippocampal levels of cytokines compared with nonsurgical rats. PEE had no effects on novel object preference in nonsurgery animals (78.6 ± 10.7%), whereas it attenuated surgery-induced impairment of novel object preference (70.9 ± 15.0%, P < 0.05 vs. sedentary/surgery group) as well as increase of cytokine levels in hippocampus. Furthermore, upon ex vivo stimulation with lipopolysaccharide, cytokines release from hippocampal microglia isolated from aged rats before intervention was significantly higher in comparison with young rats. PEE resulted in reduction of these age-related microglial phenotypic changes.
  
  
  CONCLUSIONS
  PEE could prevent the development of neuroinflammation and related POCD in aged rats by reversion of a proinflammatory phenotype of hippocampal microglia.
authors.affiliation: From the Department of Anesthesiology and Critical Care Medicine, Kochi Medical School, Kochi, Japan (T.K., H.I., T.T., M.Y.); Department of Dental Anesthesiology, Tokushima University School of Dentistry, Tokushima, Japan (S.E.); and Department of Advanced Medical Technologies, Clinical Trial Center, Kochi Medical School, Kochi, Japan (N.K.).
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawano
authors.forename: Satoru
authors.initials: S
authors.lastname: Eguchi
authors.forename: Hideki
authors.initials: H
authors.lastname: Iwata
authors.forename: Takahiko
authors.initials: T
authors.lastname: Tamura
authors.forename: Naoko
authors.initials: N
authors.lastname: Kumagai
authors.forename: Masataka
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D000005:Abdomen / Q000601:surgery; D000818:Animals; D003072:Cognition Disorders / Q000517:prevention & control* / Q000523:psychology; D004195:Disease Models, Animal; D007813:Laparotomy / Q000009:adverse effects* / Q000523:psychology; D008297:Male; D017628:Microglia / Q000378:metabolism / Q000473:pathology; D011183:Postoperative Complications / Q000517:prevention & control* / Q000523:psychology; D011300:Preoperative Care / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D012931:Social Environment