title: Environmental enrichment reverses cognitive impairments provoked by Western diet in rats: Role of corticosteroid receptors.
abstract: OBJECTIVE
  Previous studies demonstrated that the Western diet (WD), which is rich in saturated fat (HFD) and refined sugar (HSU), is related to the impairments of hippocampus-dependent learning and memory and forebrain synaptic plasticity in rodents. The environmental enrichment (EE) has been shown to enhance learning and memory in the HFD-induced cognitive deficits, but the exact mechanism is still not clearly understood. Therefore, the present study aimed to clarify the effects of the EE on spatial memory in WD-fed rats, and to analyze the potential role of corticosteroid receptors in the EE conditioning.
  
  
  METHODS
  Male Wistar albino rats were housed in either an enriched or standard environment and fed with the HFD (35% of energy as fat), HSU (100% of carbohydrate as sucrose) or standard rat chow for 4weeks. We used the Morris' water maze test (MWM) to assess the learning and memory performance, and measured plasma levels of corticosterone (CORT) and adrenocorticotropic hormone (ACTH), as well as glucocorticoid (GR) and mineralocorticoid receptor (MR) levels in the hippocampus.
  
  
  RESULTS
  The results showed that HFD-fed rats displayed poorer learning and memory performance evaluated with MWM than controls. The EE reversed the cognitive deficits caused by the HFD. In addition, the EE resulted in an increase of GR and MR levels without affecting plasma CORT and ACTH concentrations.
  
  
  CONCLUSIONS
  Based on these findings, it could be suggested that the EE plays an important role in amelioration of the HFD-induced cognitive impairments, but this intervention is independent of the hypothalamic-pituitary-adrenal axis and hippocampal corticosteroid receptor levels.
authors: Department of Physiology, Faculty of Medicine, Selcuk University, Konya, Turkey.
authors: Hasan Serdar
authors: HS
authors: Gergerlioglu
authors: Department of Physiology, Faculty of Medicine, Bozok University, Yozgat, Turkey. Electronic address: ozmhmt@gmail.com.
authors: Mehmet
authors: M
authors: Oz
authors: Department of Physiology, Faculty of Medicine, Mustafa Kemal University, Hatay, Turkey.
authors: Enver Ahmet
authors: EA
authors: Demir
authors: Department of Pharmacology, Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey.
authors: Kismet Esra
authors: KE
authors: Nurullahoglu-Atalik
authors: Department of Biochemistry, Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey.
authors: Fatma Humeyra
authors: FH
authors: Yerlikaya
mesh_terms: D000818:Animals; D003072:Cognition Disorders / Q000209:etiology / Q000378:metabolism* / Q000628:therapy*; D059305:Diet, High-Fat / Q000009:adverse effects; D066273:Diet, Western / Q000009:adverse effects*; D004777:Environment; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism; D008297:Male; D018782:Maze Learning / Q000502:physiology; D010913:Pituitary-Adrenal System / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018161:Receptors, Mineralocorticoid / Q000502:physiology; D011987:Receptors, Steroid / Q000502:physiology*
chemical_list: D018161:Receptors, Mineralocorticoid; D011987:Receptors, Steroid
keywords: Cognitive function; Enriched environment; Glucocorticoid receptor; Mineralocorticoid receptor; Water maze; Western diet