September 17, 2001
Luskin: More brain cells capable of regneration
Emory researchers have demonstrated that several regions of the adult
rat brain have the capacity to acquire new neurons following the introduction
of a growth factor into the brains lateral ventricle, located in
the depths of the cerebral cortex.
The study is the first to show the presence of numerous new neurons in
regions of the brain where they previously have not been found, and it
suggests that the adult brain may be able to replace neurons lost due
to injury or disease. The results were published in the Sept. 1 issue
of the Journal of Neuroscience.
The research team, headed by Professor of Cell Biology Marla Luskin,
also included cell biology fellow Viorica Pencea, Kimberly Bingaman and
Stanley Wiegand of Regeneron Pharmaceuticals.
The Emory scientists administered the growth factor BDNF (brain-derived
neurotrophic growth factor) into the lateral ventricle of the brains of
adult rats for approximately two weeks, then waited another two weeks
before examining the brains for the presence of new cells. They detected
newly generated neurons in several forebrain structures, including in
the paren-chyma (gray matter) of the striatum, septum, thalamus and hypothalamusareas
that serve a multitude of cognitive and vital neurological functions.
The newborn cells were identified by infusing the brain with the cell
proliferation marker BrdU, which serves as a permanent label for new cells,
in conjunction with the BDNF. Until this study was done, neurogenesis
(the production of neurons) had not been demonstrated in the thalamus
and hypothalamus during postnatal life, and in only very limited numbers
in the septum and striatum.
Earlier studies had shown that most new cells in the adult brain originate
in the subventricular zone surrounding the lateral ventricles.
Luskins experiments showed that a specialized region of the postnatal
subventricular zone contains progenitor cells whose progeny (daughter
cells) migrate along a pathway known as the rostral migratory stream to
the olfactory bulb.
Luskin and her colleagues demonstrated that the special region of the
subventricular zone and the rostral migratory stream contain a unique
population of dividing neurons (neuronal progenitor cells); everywhere
else in the brain, neurons are post-mitotic (unable to divide). Luskins
previous work demonstrated that BDNF infusion leads to an immense increase
in the numbers of new neurons in the rostral migratory stream and olfactory
bulb, a portion of the brain involved in the processing of smells.
These studies led us to investigate whether infusing BDNF could
influence the proliferation and/or survival of neurons in other regions
of the adult forebrain as well, Luskin said. The number of
new neurons we found in regions such as the striatum and hypothalamus
suggests to us that the adult forebrain has a more profound capacity to
produce new neurons than previously has been recognized.
The researchers hope their findings may reveal novel ways of producing
large numbers of new neurons to replace diseased or damaged cells in localized
parts of the brain. Future studies will continue to address the mode of
action of BDNF, whether the population of new neurons is sustained long
after the infusion of BDNF is terminated and whether cells within the
gray matter parenchyma can divide when exposed to BDNF, as the studies
The research was supported by grants from the National Institute of Deafness and Other Communicative Disorders of the National Institutes of Health.