Nanoparticles in the brain
Tiny particles enter the brain
after being inhaled.
9 January 2004
JIM GILES
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| Brain cells that
pick up smell can carry nanoparticles
inside. |
| © SPL |
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Nanoparticles - tiny lumps of matter that could one
day to be used to build faster computer circuits and
improve drug delivery systems - can travel to the brain
after being inhaled, according to researchers from the
United States1.
The finding sounds a cautionary note for advocates
of nanotechnology, but may also lead to a fuller understanding
of the health effects of the nanosized particles produced
by diesel engines.
Gunter Oberdorster of the University of Rochester
in New York and colleagues tracked the progress of carbon
particles that were only 35 nanometres in diameter and
had been inhaled by rats. In the olfactory bulb - an
area of the brain that deals with smell - nanoparticles
were detected a day after inhalation, and levels continued
to rise until the experiment ended after seven days.
"These are the first data to show this," says Ken Donaldson,
a toxicologist at the University of Edinburgh, UK. "I
would never have thought of looking for inhaled nanoparticles
in the brain."
Substances such as drugs can cross from the brain into
the blood, but Oberdorster believes that the carbon
nanoparticles enter the brain by moving down the brain
cells that pick up odours and transmit signals to the
olfactory bulb. He says that unpublished work, in which
his group blocked one of the rats' nostrils and tracked
which side of the brain the nanoparticles reached, appears
to confirm this.
Little is known about what effect nanoparticles will
have when they reach the brain. The toxicity of the
nanoparticles that are currently being used to build
prototype nanosized electronic circuits - such as carbon
nanotubes, which are produced in labs around the world
- has not been thoroughly assessed.
But Donaldson says that there is a growing feeling
that other nanoparticles, such as those produced by
diesel exhausts, may be damaging to some parts of our
body. He estimates that people in cities take in about
25 million nanoparticles with every breath. These particles
are believed to increase respiratory and cardiac problems,
probably by triggering an inflammatory reaction in the
lungs.
Oberdorster's unpublished work includes evidence
that some nanoparticles may trigger a similar inflammatory
reaction in the brains of rats.
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