| March 28, 2001
Penn Researchers Explain the
Mechanics behind the Delayed Effects of Brain Trauma;
Findings May Chart Paths to Therapeutic Relief
(Philadelphia, PA) - The
initial twist and snap of physical injury to nerve cells
and fibers in the brain during head trauma is only the
beginning of the damage. In particular, the stretching
of nerve fibers, or "axons", can induce progressive
damage leading to long-term problems such as memory
dysfunction and difficulties with concentration.
Researchers at the University of Pennsylvania Medical
Center have determined that one of the initial events
triggering these long-term problems includes a massive
flood of calcium ions, electrically charged calcium
atoms, that enter axons following brain trauma. In addition,
their study suggests a possible course of treatment
for this pathologic process. The results of the study
are published in The Journal of Neuroscience's March
issue.
Previously, researchers had only postulated that calcium
entry into damaged axons was an important indicator
for the start of progressive damage. Now this has not
only been demonstrated, but a mechanism of this calcium
entry has been discovered. "It appears that that the
physical motions of trauma literally tears open proteins
that act as gates on the axon membrane," explains Douglas
Smith, MD, an associate professor in the Penn Department
of Neurosurgery.
Surprisingly, the gates that were forced open were
not for calcium ions, but for sodium ions. "We have
now found that it is the rapid flow of sodium ions through
the damaged gates that triggers a subsequent inflow
of calcium ions," said Smith. "With this knowledge,
we can evaluate therapies that block the sodium channels."
Early therapy targeting sodium channels may be critical
to preventing the progressive damage to axons, which
has been previously found by this research team. "It
can be hours, even months, after a head injury before
the damage to the axons becomes so severe that the neurons
can no longer function," says Smith. "There is currently
no cure to stop the delayed effect of head trauma, but
we are convinced that the damage can be slowed down
and, eventually, even stopped."
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