Levels of brain-derived neurotrophic factor (BDNF) stop declining when Huntington's disease transgenic mice are housed in an enriched environment, the scientists say. BDNF promotes neuron growth and survival and can also regulate communication between neurons.
"The finding that environmental enrichment increases BDNF, and that this slows disease progression, provides a potential mechanism for the effects of environmental enrichment on Huntington's disease," says M. Flint Beal, chair of neurology at Cornell University Medical College in New York.
The new study appears in the March 3 issue of The Journal of Neuroscience and was supported by the U.K. Medical Research Council.
Huntington's disease is a genetic brain disorder that usually strikes in midlife. As the disease progresses, patients experience involuntary dancelike movements called chorea, as well as cognitive decline. Currently, there are no effective treatments, and patients with the disease usually die 10 to 20 years after onset. The disorder affects approximately 30,000 Americans.
In the study, enriched mice had play objects placed in their cages that changed every two days, such as small, open, wooden boxes and cylindrical cardboard tunnels. To measure motor symptoms, the researchers placed five-month-old enriched and nonenriched mice on the central cylinder of a rotarod apparatus. The cylinder rotated, slowly at first, then accelerating. The amount of time a mouse remained on the rotating rod was a measure of Huntington's disease-associated motor symptoms.
In transgenic mice housed without enrichment, BDNF protein levels declined, but in mice housed in enriched conditions, the levels remained normal. Enriched mice also showed fewer Huntington
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