Brain Cells that Generate Breathing Pinpointed

Keywords: BREATHING DISORDERS SLEEP APNEA SIDS BRAIN

Description: For the first time, scientists have identified the small group
of brain cells believed to originate breathing in mammals. Reported in the
September issue of Nature Neuroscience, their discovery could lead
researchers to new approaches to addressing serious health problems, such
as sleep apnea and sudden infant death syndrome. (Nature Neuroscience;
Sept-2001)


Neurobiologists Identify Brain Cells That Control Breathing

For the first time, UCLA scientists have identified the small group of
brain cells believed to originate breathing in mammals. Reported in the
September issue of Nature Neuroscience, their discovery could lead
researchers to new approaches to addressing serious health problems, such
as sleep apnea and sudden infant death syndrome.

In a previous study, the UCLA team had pinpointed a specific region of
brain tissue called the preBštzinger Complex as the command post for
controlling breathing in mammals. Now, within the region, they
distinguished a small group of neurons responsible for issuing the commands
that generate breathing.

"We hypothesized that if these neurons were important, something unusual
would happen to breathing if we destroyed them," explained Dr. Jack
Feldman, Edith Agnes Plum Professor, UCLA neurobiology chair and principal
investigator. "As it turned out, we were right."

Using a rat model, the UCLA team zeroed in on the roughly 600 neurons -
less than one millionth of one percent of the total neurons in an adult
rat's brain. The researchers stained a unique marker on the cells' surfaces
to identify and count them. Then they administered a toxin that targeted
the marker to kill just these cells.

The results proved striking in animals that lost more than 80 percent of
their neurons.

"These rats' breathing dissolved from a regular, rhythmic pattern into a
highly irregular pattern of breathing frequency and depth," said Dr. Paul
Gray, UCLA neurobiologist and first author. "Equally important, the rats'
brains stopped controlling the amounts of oxygen and carbon dioxide in the
bloodstream - the whole point of breathing," he added.

While the findings prove the necessary role of these neurons in normal
breathing, UCLA researchers are equally excited by the study's implications
for the future.

"Our findings suggest that these neurons may hold the underlying causes of
breathing disorders and offer an excellent target for drugs treating these
disorders," said Feldman.

Because mammals' brains are organized in similar ways, Feldman believes
that the same portion of the human brain will likely control breathing as
in rats.

The UCLA team's next step will be to locate the same set of neurons in a
human brainstem and then compare their physiology and function with the
neurons of people with breathing disorders. If his hypothesis proves
correct, Feldman may find fewer or dysfunctional neurons in the brains of
people with breathing disorders.

Funding was provided by the National Institutes of Health, a Ford
Foundation Predoctoral Fellowship for Minorities and the Porter Physiology
Development Program of the American Physiological Society. Drs. Wiktor
Janzewski, Nicholas Mellen and Donald McCrimmon co-authored the study.

-UCLA-

Rob Kall
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