新消息分享

lsqsmz

Scientists eye an enzyme as target in fighting autism

Wed Jun 27, 9:11 AM ET

CHICAGO (AFP) - US researchers have reversed the symptoms of mental
retardation and autism in mice by inhibiting an enzyme that affects
the connections between brain cells, researchers said Wednesday.
ADVERTISEMENT

In a series of experiments on mice, the MIT investigators showed that
they could undo the brain damage seen in a condition called Fragile X
syndrome by inhibiting a key brain chemical called PAK.

In humans, Fragile X syndrome (FXS) is the leading cause of mental
retardation and the most common genetic cause of autism -- the complex
and devastating developmental disorder that is now being diagnosed in
increasing numbers of children.

The study raises the intriguing possibility that the brain damage seen
in children with the condition can be rolled back and identifies a
specific target for potential drug therapies.

"It opens up a new avenue for drug research to treat this condition,"
said Susumu Tonegawa, a neuroscientist at the Massachusetts Institute
of Technology in Cambridge, Massachusetts, and lead author of the
paper.

MIT researchers began by creating a batch of mice that had been
genetically modified to have Fragile X, a condition in which the
neurons of the brain are structurally abnormal and functionally
impaired compared to regular nerve cells.

These transgenic mice had many of the behavioral problems seen in kids
with the condition: hyperactivity, attention deficits, repetitive
behaviors and poor social skills.

The investigators then cross-bred these mice with another batch of
mice that had been genetically modified to inhibit the activity of the
PAK (p21-activated kinase) enzyme which is instrumental in shaping the
formation of neuronal connections in the brain.

The researchers knew that when PAK was inactivated, the mice developed
neurons that had short, fat dendritic spines, with a higher-than-usual
capacity for relaying the electrical impulses that pass between brain
cells.

In other words, the shape and function of the dendritic spines in the
PAK mice was just the reverse of those seen in the brain cells of the
mice with Fragile X syndrome.

The researchers gambled that the two abnormalities would cancel each
other out, and that's exactly what the experiment showed.

The cross-bred mice had been genetically engineered so that the
inactivation of the PAK enzyme began two weeks into the mouse's life
cycle, which in human terms would be several years after birth.

Tests and autopsies showed that the PAK-blocking action restored
electrical communication between neurons in the brains of the double
mutant mice, correcting their behavioral abnormalities in the process.

"This is very exciting because it suggests that PAK inhibitors could
be used for therapeutic purposes to reverse already established mental
impairments in fragile X children," said Eric Klann, a professor at
New York University's Center for Neural Science.

The study was conducted by Tonegawa and a postdoctoral student at
MIT's Picower Institute for Learning and Memory and appears in this
week's edition of the Proceedings of the National Academy of Sciences.

dc07

谢谢分享.

######
In humans, Fragile X syndrome (FXS) is the leading cause of mental
retardation and the most common genetic cause of autism
######
我儿子查过,不是.