FRIDAY, July 13, 2001 (HealthDayNews) -- Men who were exposed to methamphetamine in the womb may end up at higher risk for brain damage than women if they use the drug themselves.
New research in rodents shows that the male offspring of mothers who took meth while they were pregnant responded more strongly to the drug as adults than did female offspring -- and the response suggested greater vulnerability to meth's harmful effects on brain cells.
"It's not good to use meth, period. But if your mother used meth, and you're a male, you're putting yourself at even greater risk," says Dr. Alfred Heller, a neuroscientist at the University of Chicago and lead author of the study. The findings appear in the latest issue of the Journal of Pharmacology and Experimental Therapeutics. The key question, Heller asks, is "How do you know if your mother used meth?"
Methamphetamine, also known as "crank," "ice" and "chalk," has become the second-most popular illicit drug on the planet, according to the World Health Organization. The stimulant is easy to make, cheap to buy, and gives a relatively long-lasting high. Many women have used the chemical to help suppress appetite and lose weight, and for its mood-lifting powers.
Although users may think methamphetamine is safe, scientists say otherwise. Studies have shown that the drug damages brain cells, particularly those neurons involved in the relay of dopamine, a messenger molecule important in mental abilities and physical coordination.
As a result, meth users may have a greater risk of getting Parkinson's disease, a devastating neurological disorder, and even schizophrenia, though the drug's long-term effects aren't well understood. Research has also linked meth use in women to premature delivery and to irritability in their babies.
In the latest work, Heller and his colleagues gave a certain dose of meth to the pregnant female mice, and then gave varying doses to their offspring when they'd reached 11 weeks of age, or mouse adulthood. They tried to give the mice the kind of realistic doses a human fetus would be exposed to in a meth mother's womb.
Males exposed to meth as fetuses showed a much stronger reaction to the drug the second time around than females did, Heller says. The male brains released far more dopamine in two areas, the substantia nigra (gray matter) and the striatum (located near the center of the brain).
The flood of dopamine in response to meth is believed to be the chief reason for why it kills nerve endings through oxidative stress.
The reason for the gender difference isn't clear, Heller says, but it might be linked to differences in body temperature. Methamphetamine raises core temperature, more so in males than in females. In the Chicago study, the strength of the dopamine response to meth was associated with the male mice having a naturally higher body temperature.
Dean Dluzen, an anatomist at Northeastern Ohio Universities College of Medicine in Rootstown, who has studied meth in mice, says the female hormone estrogen could help explain the gender difference.
In a recent study, Dluzen found that removing the ovaries of female mice -- and thus stripping them of estrogen -- deprived their brains of protection from meth. But giving them estrogen restored the shield.
"One thing estrogen does is reduce body temperature," he says, suggesting that the reduced body temperature diminishes the effects of drugs.
Dluzen also believes estrogen lessens the effect of meth on dopamine receptors by keeping them from taking up too much of the signaling molecule once it's released in massive quantities.
Heller, however, discounts estrogen's role and suspects that it's the male hormone testosterone that makes the real difference. But he calls his theory "pure conjecture at this point."
In addition to exploring that question further, Heller says his group hopes to look at gender differences in response to prenatal exposure to other drugs, including cocaine and ecstasy.
What To Do
For more on methamphetamine, visit the Koch Crime Institute. You can also try the National Institute on Drug Abuse.
