The Effect of Long-Term Environmental Enrichment in Chronic Cerebral Hypoperfusion-Induced Memory Impairment in Rats

Vascular dementia (VaD) is the second most common cause of dementia. It occurs when the cerebral blood supply is reduced by disarrangement of the circulatory system. Environmental enrichment (EE) has been associated with cognitive improvement, motor function recovery, and anxiety relief with respect to various neurodegenerative diseases and emotional stress models. The purpose of this study was to determine whether long-term EE influenced cognitive impairment in a rat model of chronic hypoperfusion induced by permanent occlusion of bilateral common carotid arteries (BCCAo). The Y-maze and Morris water maze tests were performed to evaluate the rats' cognitive functions. Also, the protein expression of brain-derived neurotrophic factor (BDNF), phosphorylated cAMP-calcium response element binding protein (pCREB), and vascular endothelial growth factor (VEGF) were confirmed by Western blot. The microvessels and angiogenesis-associated proteins in the hippocampal region were investigated using immunohistochemistry. The VaD + EE group showed significantly better cognitive functions than the VaD group in both the Y-maze and MWM tests. In addition, the VaD + EE group showed significantly increased expression of BDNF, pCREB, and VEGF in the hippocampus compared to the VaD group. Rats in the VaD + EE group also had increased length of microvessels and VEGF expression in the hippocampus. These results suggest that long-term EE exerts neuroprotective effects against cognitive impairment induced by chronic cerebral hypoperfusion through the enhancement of BDNF, pCREB, and VEGF expression and indicate that EE may be a good nursing intervention in vascular dementia patients.