The findings suggest that the compound, or others like it, could be used in
treating mental impairment associated with alcoholism, the researchers said.
While it has long been known that alcohol abuse can impair memory and other
mental abilities, it is not yet clear exactly how alcohol harms brain cells.
In the new study, researchers found that rats fed alcohol formed fewer new
brain cells, or neurons, and showed greater cell death than those on a normal
diet.
"We demonstrated that in a model of alcoholism, neurogenesis (brain-cell
formation) was impaired," Dr. Daniel G. Herrera, of Weill Medical College of
Cornell University in New York, told Reuters Health.
This impairment, Herrera explained, occurred, at least in part, because newly
formed cells were dying.
According to the researcher, substances with antioxidant properties have been
shown to prevent the death of liver cells. So Herrera's team hypothesized that
antioxidants -- which neutralize cell-damaging forms of oxygen called free
radicals -- might similarly protect brain cells from alcohol damage.
To investigate, the researchers fed rats either a regular liquid diet or one
that contained ethanol (alcohol). Some of the rats in each group also received a
potent synthetic antioxidant called ebselen.
After six weeks, rats fed alcohol showed a 66 percent decrease in the number
of new neurons and a two- to three-fold increase in cell death in a portion of
the brain, when compared with rats that ate a regular diet.
In rats that got both alcohol and ebselen the scientists saw no similar
reduction in brain-cell formation and no increase in cell death.
The findings are published online in the Proceedings of the National Academy
of Sciences Early Edition.
Studies in recent years have indicated that alcohol may affect different
brain areas in different ways, according to Herrera. In the rat study,
neurogenesis was impaired in a brain structure called the dentate gyrus, which
is located in the hippocampus, the brain's "memory center."
"Effects on neurogenesis could give an alternative explanation to how alcohol
affects certain brain structures and specific cognitive functions more than
others," Herrera said.
What's more, he and his colleagues write, their findings suggest that ebselen
or similar compounds could be useful in treating mental impairment in alcoholics
-- and possibly in other brain disorders where neurogenesis might be affected.
However, Herrera said, more research is needed into the precise role of
neurogenesis in brain function and repair.
SOURCE: Proceedings of the National Academy of Sciences Early Edition
2003;10.1073/pnas.1230907100.
