SAN DIEGO---Estrogen may make the brain more vulnerable to addiction, with the effects of this heightened susceptibility persisting even in the hormone's absence, according to a University of Michigan study presented Nov. 14 at the 2001 meeting of the Society for Neuroscience in San Diego.
"Years ago, people said that women shouldn't smoke or drink because we were more likely to become addicted," says U-M biopsychologist Jill B. Becker, who conducted the research, which is funded by the National Institute on Drug Abuse (NIDA). "I'm a feminist and don't subscribe to old-school ideas that women are the 'weaker' sex in need of protection.
"Yet these new findings suggest that when it comes to drug use, women should be extremely cautious, especially younger women who may be experiencing major hormonal swings at just the same time in their lives when many of their peers are first experimenting with nicotine, cocaine and other addictive substances." Older women using HRT may also increase their vulnerability to drug addiction.
At the meeting, Becker will present new data from a series of studies on approximately 200 rats showing that female rats who received estrogen as well as cocaine over a period of three weeks exhibit 20 percent to 50 percent more "sensitization" than either female rats who did not receive estrogen or male rats. Sensitization was measured by quantifying repetitive movements of the head and forelimbs, and turning in circles.
Drug sensitization is thought to cause craving for a drug like cocaine, Becker notes. For example, rats who are sensitized after repeated drug doses learn to self-administer cocaine faster and at lower doses than other animals. These changes in behavior persisted after the female rats, all of whose ovaries had been surgically removed, stopped receiving estrogen, Becker reports.
"We know from other studies that sensitization to cocaine results in structural changes in the brain that
Contact: Diane Swanbrow
University of Michigan