Washington USA
— (Reuters) - Too much testosterone can kill
brain cells, researchers said on Tuesday in a finding
that may help explain why steroid abuse can cause
behavior changes like aggressiveness and suicidal
tendencies.
Tests on brain cells in
lab dishes showed that while a little of the male hormone
is good, too much of it causes cells to self-destruct in
a process similar to that seen in brain illnesses such as
Alzheimer's.
"Too little testosterone
is bad, too much is bad but the right amount is perfect,"
said Barbara Ehrlich of Yale University in Connecticut,
who led the study.
Testosterone is key to
the development, differentiation and growth of cells and
is produced by both men and women, although men produce
about 20 times more of the hormone.
It can also be abused,
and recent scandals have involved athletes who use the
hormone, or steroids that turn into testosterone in the
body, for an unfair advantage.
"Other people have shown
that high levels of steroid can cause behavioral
changes," Ehrlich said in a telephone
interview.
"We can show that when
you have high levels of steroids, you have high
testosterone and that can destroy the nerve cells. We
know that when you lose brain cells you lose
function."
Ehrlich's team tried the
same thing with the "female" hormone estrogen, just to be
fair.
"We were surprised, but
it actually looks like estrogen is neuroprotective. If
anything, there is less cell death in the presence of
estrogen," she said.
Writing in the Journal
of Biological Chemistry, Ehrlich and colleagues said
their findings meant people should think twice about
supplementing with testosterone, even if it does build
muscle mass and aid recovery after exercise.
"These effects of
testosterone on neurons will have long term effects on
brain function," they wrote.
"Next time a muscle-bound
guy in a sports car cuts you off on the highway, don't
get mad -- just take a deep breath and realize that it
might not be his fault," Ehrlich said in a
statement.
The cells die via a
process called apoptosis, also known as cell suicide or
programmed cell death.
"Apoptosis is an
important thing for the brain -- the brain needs to weed
out some of the cells. But when it happens too
frequently, you lose too many cells and causes
problems."
A similar process is seen
in Alzheimer's disease, the most common cause of dementia
in the United States, affecting an estimated 4.5 million
Americans, and Huntington's disease, another fatal brain
illness.
"Our results suggest that
the responses to elevated testosterone can be compared
with these pathophysiological conditions," the
researchers wrote.
