By Kate Kelland
LONDON, Aug 14 (Reuters) - Scientists have genetically
modified mice to be super-intelligent and found they are also
less anxious, a discovery that may help the search for
treatments for disorders such as Alzheimer's, schizophrenia and
post traumatic stress disorder (PTSD).
Researchers from Britain and Canada found that altering a
single gene to block the phosphodiesterase-4B (PDE4B) enzyme,
which is found in many organs including the brain, made mice
cleverer and at the same time less fearful.
"Our work using mice has identified phosphodiesterase-4B as
a promising target for potential new treatments," said Steve
Clapcote, a lecturer in pharmacology at Britain's Leeds
University, who led the study.
He said his team is now working on developing drugs that
will specifically inhibit PDE4B. The drugs will be tested first
in animals to see whether any of them might be suitable to go
forward into clinical trials in humans.
In the experiments, published on Friday in the journal
Neuropsychopharmacology, the scientists ran a series of
behavioural tests on the PDE4B-inhibited mice and found they
tended to learn faster, remember events longer and solve complex
problems better than normal mice.
The "brainy" mice were better at recognising a mouse they
had seen the previous day, the researchers said, and were also
quicker at learning the location of a hidden escape platform.
They were also less able to recall a fearful event after
several days than ordinary mice, and as PDE4B is also found in
humans, this could be of interest in the search for treatments
for brain conditions as well as mental decline linked to ageing.
The experiments also showed that PDE4B-inhibited mice
suffered less anxiety, choosing to spend more time in open,
brightly lit spaces than normal mice, which preferred dark,
enclosed spaces.
And while mice are naturally scared of cats, the modified
mice responded less fearfully to cat urine, suggesting that
inhibiting PDE4B could increase risk-taking behaviour.
(Editing by Louise Ireland)