Effects of environmental enrichment on anxiety-like behavior, sociability, sensory gating, and spatial learning in male and female C57BL/6J mice

Abstract

The influence of housing on cognition and emotional regulation in mice presents a problem for the study of genetic and environmental risk factors for neuropsychiatric disorders: standard laboratory housing may result in low levels of cognitive function or altered levels of anxiety that leave little room for assessment of deleterious effects of experimental manipulations. The use of enriched environment (EE) may allow for the measurement of a wider range of performance in cognitive domains. Cognitive and behavioral effects of EE in male mice have not been widely reproduced, perhaps due to variability in the application of enrichment protocols, and the effects of EE in female mice have not been widely studied. We have developed an EE protocol using common laboratory equipment that, without a running wheel for exercise, results in significant cognitive and behavioral effects relative to standard laboratory housing conditions. We compared male and female wild-type C57BL/6J mice reared from weaning age in an EE to those reared in a standard environment (SE), using common measures of anxiety-like behavior, sensory gating, sociability, and spatial learning and memory. Sex was a significant factor in relevant elevated plus maze (EPM) measures, and bordered on significance in a social interaction (SI) assay. Effects of EE on anxiety-like behavior and sociability were indicative of a general increase in exploratory activity. In male and female mice, EE resulted in reduced prepulse inhibition (PPI) of the acoustic startle response, and enhanced spatial learning and use of spatially precise strategies in a Morris water maze task.

Keywords: Elevated plus maze; Environmental enrichment; Prepulse inhibition; Sex differences; Spatial strategies; Water maze.