An enriched environment promotes cognitive recovery and cerebral blood flow in aged mice under sevoflurane anaesthesia

Sevoflurane is an inhalation anaesthetic agent widely used in clinical settings. Despite good surgical outcomes using sevoflurane, patients frequently develop postoperative cognitive dysfunction (POCD). An enriched environment (EE), as a rehabilitation technique, could provide objects and tools to facilitate neuromotor and visual stimuli and brain activity, and is reported to improve cognitive functions. We aim to investigate the impairments of sevoflurane inhalation on cognitive function in mice and determine the benefits of EE in ameliorating POCD. Eighteen-month-old mice were exposed to sevoflurane inhalation for 2 h and then placed in standard environment (SE) or EE cages. The mice without sevoflurane exposure in standard or EE cages were used as controls. The behavioural tests include Morris water maze, Y maze and novel object recognition. Magnetic resonance imaging (MRI) was used to determine the blood circulation in the brains. The proangiogenic factors (CD31, angiopoietin-1, vascular endothelial growth factor, and N-cadherin) and neurotrophic (brain-derived neurotrophic factor, post-synaptic density protein 95) expression in hippocampus of aged mice were evaluated by Western blotting and RT-PCR analysis. Sevoflurane-exposed mice demonstrated reduced performance in learning, memory and spatial memory tests. Enriched environment improved the behavioural performance of sevoflurane-exposed animals. Sevoflurane exposure reduced the blood flow in the brains, and these effects were ameliorated by EE habitation. The EE also promoted the expression of angiogenic and neurotropic factors in sevoflurane-exposed animals. In summary, EE is effective in ameliorating the side-effects of sevoflurane exposure in aged mice.