WEDNESDAY, Dec. 3, 2003 (HealthDayNews) -- Estrogen may make women more sensitive to the effects of stress, says a study in the December issue of Molecular Psychiatry.
In experiments with rats, the researchers examined the effects of stress on the function of a brain area called the prefrontal cortex (PFC), which governs cognitive abilities such as short-term memory and concentration.
Previous research found these functions are disrupted when rats are exposed to stress. But most of those studies were done with male rats. It was unclear how gender differences affected the PFC response to stress.
In this new study, female and male rats were exposed to different levels of stress and then tested on short-term memory task. When they were stress-free, both the male and female rats performed equally well on the task. Both the male and female rats made major memory errors after being exposed to high levels of stress.
However, after exposure to moderate levels of stress, the female rats showed impaired ability on the memory task while the male rats did not. That suggests the female rats are more sensitive to the PFC-impairing effects of stress.
The researchers monitored the female rats' estrus cycles and found they showed this sensitivity to moderate stress only when they were in a high-estrogen phase.
To further investigate the effect of estrogen, they removed the ovaries of a new group of female rats, which meant those rats had no circulating estrogen. A time-capsule containing either estrogen or placebo was placed in these female rats.
The altered rats were then subjected to the same stress and memory tests. The study found the implanted estrogen created the same sensitivity to stress as natural estrogen.
The researchers concluded that high levels of estrogen act to enhance the stress response, resulting in greater stress-related cognitive impairments.
A better understanding of this process may lead to a better understanding of why women are more susceptible to stress-related disorders such as depression and post-traumatic stress disorder. That could help in the development of improved treatments for those disorders.
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