FRIDAY, Nov. 2, 2001 (HealthDayNews) -- Did you ever wonder why men are often more aggressive than women? While testosterone has shouldered most of the blame for boorish behavior, another chemical may play a significant role.
Researchers from the University of Akron in Ohio set out to build on previous research that found male rats with reduced levels of the brain chemical serotonin were more aggressive. They theorized that lower-than-normal serotonin levels might be caused by a malfunctioning gene.
"When the neurotransmitter serotonin gets low, there is an increased amount of aggressive activity," says Daniel Ely, one of the researchers and a professor of biology at the university.
Ely's team bred male rats with reduced levels of serotonin, then conducted "resident intruder" tests in which new animals were put into an existing colony of rats.
New female rats were not attacked by the residents rats, but new male rats were attacked about three times in 15 minutes, and with enough force to cause two scars in that time period.
The researchers say a gene on the Y chromosome, the male chromosome, is responsible for the reduction in serotonin, and that decreased levels are likely responsible for the increased aggression.
The findings were presented at a recent meeting of the American Physiological Society in Pittsburgh. Ely and his colleagues say they hope to continue their work to identify the specific gene responsible for reducing serotonin levels.
Ely says the results don't necessarily extend to humans.
Dr. Kenneth Skodnek, chairman of the departments of psychiatry and psychology at Nassau University Medical Center, in New York, says serotonin "very clearly plays a role in aggression." He says he sees this in his practice when he puts patients who are depressed or suffer from anxiety on anti-depressant medications known as selective serotonin reuptake inhibitors (SSRIs), he says.
People on SSRIs are calmer, more focused, have better control of their tempers and get along better with people, Skodnek says.
What to Do: To learn more about the physiological reasons for aggression, read this article on the Bryn Mawr College Web site. For more on how serotonin affects your emotions, check the California State University, Chico site.
