Local cerebral glucose utilization in rats exposed to an enriched environment: A comparison to impoverishment

Environmental enrichment and environmental impoverishment have been shown to differentially alter brain function. Here, we investigate the effects of enrichment vs. impoverishment on cerebral use of glucose in rodents. Rats were housed from postnatal day 28 to day 58 in either a socially and environmentally enriched environment or an impoverished environment devoid of other rats or environmental stimuli. Locomotor activity was measured at the end of the enrichment/impoverishment period. Following the duration of the exposure to these environments, cerebral metabolic rate of glucose utilization was determined using quantitative 2-[14C]deoxyglucose autoradiography in 37 brain regions in the cerebral cortex, forebrain, brain stem and thalamus. There were no differences in locomotor activity between the conditions. The nucleus accumbens core and shell had significantly higher rates of glucose utilization in enriched compared to impoverished animals. These data suggest that environment has a significant effect on brain function which may help to explain the beneficial and protective effects of enrichment against drug abuse and addiction.

Research Highlights
► Environmental enrichment and social housing during adolescence produced increased functional brain activity in adulthood when compared to rats reared in an impoverished environment.
► Differences in functional activity, as reflected by rates of glucose utilization, were greatest in the nucleus accumbens shell and core with rates higher in those rats reared in an enriched environment.
► These differences in brain activity occurred in the absence of differences in spontaneous locomotor behavior.