G. Scott Lett, Ph.D.
CEO, The BioAnalytics Group LLC

In the last issue of The Enrichment Record, Emily Patterson-Kane and I reported on the work (Cao, Liu et al.) in which investigators demonstrated that even short-term exposure to environmental enrichment (EE) improved resistance to cancer in a number of mouse models. The authors also measured specific physiological changes in the EE mice that led to improved cancer resistance. Now, it appears that short term exposure—ten days—to EE effect measurable physiological changes associated with improved cognitive function and memory in the diabetic mice.

Type 1 diabetes has been associated with a number of brain disturbances in human patients. Pathological hippocampal changes and cognitive deficits have been observed in animal models of diabetes. In the November 2010 issue of PLoS ONE, Beauquis, Roig et al. studied the modulation of the physiological changes by environmental enrichment in a Type 1 diabetes mouse model.  Beauquis et al. studied a widely-used mouse diabetes model, in which diabetes is induced using streptozotocin.  Equal numbers of diabetes-induced mice were assigned to standard conditions (SC) and enriched conditions (EC) for ten days. The EC cages were larger, had more nesting material, and a variety of toys, small plastic houses and tubes that were rearranged every two days.  Similar numbers of control (non-diabetic) mice were also assigned to SC and EC. They then measured a number of physiological changes in hippocampal neurons that have been associated with aging and stress in humans as well as cognitive and memory changes in diabetic mice. These changes were measured using immunohistochemistry techniques on brain tissue sections.

The EC diabetic mice showed enhanced proliferation, survival of newborn neurons and dendritic complexity of mature neurons compared to the SC diabetic mice.  In another important finding, they observed improved brain vasculature in the EC mice. The control mice (nondiabetic) did not exhibit significant changes in these parameters in enriched or standard conditions. The authors point out that there is still a need to perform learning and memory testing of diabetic mice to link these physiological changes with behavioral changes, but they conclude that this data could represent a new approach to prevention of central nervous system complications in Type 1 diabetes patients.

The authors comment that it is remarkable that there is no complete consensus about the protocols of EE used by different research groups. Given the mounting evidence that environmental conditions have a profound effect on research results, I must agree.

References

Beauquis, J., P. Roig, et al. “Short-term environmental enrichment enhances adult neurogenesis, vascular network and dendritic complexity in the hippocampus of type 1 diabetic mice.” PLoS ONE 5(11): e13993.  Cao, L., X. Liu, et al. “Environmental and genetic activation of a brainadipocyte BDNF/leptin axis causes cancer remission and inhibition.” Cell 142(1): 52-64.

The Enrichment Record Issue 6

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