Too much testosterone 'is bad'
Washington - Too much testosterone can
kill brain cells, researchers said on Tuesday in a finding that
may help explain why steroid abuse can cause behaviour 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 behavioural changes," Ehrlich said.
"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
Ehrlich's team tried the same thing with the "female"
hormone oestrogen, just to be fair.
"We were surprised, but it actually looks like oestrogen is
neuroprotective. If anything, there is less cell death in the
presence of oestrogen," 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
realise that it might not be his fault," Ehrlich said.
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."