MICE that are predestined to get Huntington鈥檚 disease stay healthier for
longer when they live in a varied environment with plenty of opportunities for
exercise, climbing and exploring, neuroscientists at Oxford University have
discovered. The finding is surprising since, in people, Huntington鈥檚 is strongly
genetic, and experts had thought it unlikely to be significantly affected by
environmental factors.
鈥淲e didn鈥檛 expect this dramatic delay,鈥� says Tony Hannan, who ran the study
with Anton van Dellen and Colin Blakemore. Reporting the findings at the
Australian Neuroscience Society meeting in Melbourne last week, Hannan said they
had expected an enriched environment to hasten the onset of the symptoms, rather
than delaying it.
鈥淚t鈥檚 enormous. It鈥檚 the first evidence that by manipulating the environment
you can delay the onset鈥攁nd possibly the severity鈥攐f the disease,鈥�
says Richard Faull, an expert in HD at the University of Auckland.
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But the effects may be less dramatic in people, because 鈥渁n enriched mouse is
more like a normal human鈥�, warns Hannan.
In people with HD, brain cells die, causing them to lose control of their
movement and leading to severe cognitive and behavioural deterioration. Mice
genetically engineered to have part of the gene that causes Huntington鈥檚 get
many of these symptoms. These include a motor impairment that prevents them
turning while walking on a horizontal pole.
By the time the engineered mice in Hannan鈥檚 study were 18 weeks old, they all
fell off the pole. But when the researchers put boxes and tunnels in the cages
of similar engineered mice, and changed the box and tunnel configuration every
two days, only 15 per cent of them failed the test at the same age. They also
performed better in another test for Huntington鈥檚 symptoms.
The enriched mice also showed changes in a brain region called the striatum,
which helps to coordinate movement. More of their striatal cells contained a
protein called calbindin, which is known to protect neurons from damage.