Posted on :
19 Jun 2010 04:37 pm
Study points to why stress may affect women more
There may be a biological reason why more women than men suffer stress-related psychiatric disorders, a study suggests.
Studying stress signaling molecules in rat brains, researchers found that females are more sensitive than males to low levels of a major stress hormone, and less able to adapt to high levels of it.
“This is the first evidence for sex differences” in this signaling system, said study leader Rita J. Valentino, a behavioral neuroscientist at The Children’s Hospital of Philadelphia. Her research appeared online June 15 in the research journal Molecular Psychiatry.
The gender differences, she explained, involve the way molecular structures on brain cell surfaces, called receptors, handle the traffic of stress signaling molecules. “Although more research is certainly necessary to determine whether this translates to humans, this may help to explain why women are twice as vulnerable as men to stress-related disorders,” she added.
Women have a higher incidence of depression, post-traumatic stress disorder, and other anxiety disorders, said Valentino.
Her research focuses on corticotropin-releasing factor, or CRF, a hormone that organizes stress responses in mammals. Analyzing the brains of rats put through a swim stress test, Valentino’s team found that in female rats, brain cells had receptors for CRF that attached more tightly to cell signaling proteins than in male rats. The receptors thus responded more strongly to the stress hormone.
Furthermore, Valentino said, stressed male rats displayed an adaptive response, called internalization, in their brain cells. These cells reduced the number of CRF receptors, and became less responsive to the hormone. In female rats this didn’t happen because a specific protein did not link up with the CRF receptor in a way that was needed for this adaptation, Valentino explained.
“We cannot say that the biological mechanism is the same in people,” she added, noting that other mechanisms and hormones play roles in human stress. But “researchers already know that CRF regulation is disrupted in stress-related psychiatric disorders, so this research may be relevant to the underlying human biology.”