Environmental Enrichment Induces Increased Cerebral Capillary Density and Improved Cognitive Function in Mice

Abstract

Enrichment provides an environment that fosters increased physical activity and sensory stimulation as compared to standard housing. Promoting and sustaining stimulation increases neuronal activity and, consequently, brain oxygen demand. The mammalian brain modulates its microvascular network to accommodate tissue energy demand in a process referred to as angioplasticity. In this study we investigated the effect of an environmental enrichment on cerebral capillary density and cognitive performance in mice. Microvascular density (N/mm²) was determined by GLUT-1 immunohistochemistry in mice (3 months old) after 3 weeks of placement in a non-enriched or an enriched environment. The Y-maze test and a novel object recognition test were used to evaluate cognitive function in the aged mice (18 months old) after 4 weeks of environmental enrichment. Compared to the non-enriched control mice, the mice with environmental enrichment had significantly higher (~30%) capillary density in cortical brain. The enriched aged mice (n = 12) showed improved cognitive function, presented as a significantly higher alternation rate in the Y-Maze test compared to the non-enriched controls (n = 8). Our data suggest that environmental enrichment may result in increased brain capillary density and improved cognitive performance.

Keywords: Aged mouse; Angiogenesis; Angioplasicity; Cognitive performance; Preconditioning.