Women are better at coping with stress than men due to the protective effect of female hormone estrogen, a new study has claimed.
Researchers from the University at Buffalo in US found that the enzyme aromatase, which produces estradiol, an estrogen hormone, in the brain, is responsible for female stress resilience.
"We have examined the molecular mechanism underlying gender-specific effects of stress," said senior author Zhen Yan, a professor in the Department of Physiology and Biophysics in the university.
"Previous studies have found that females are more resilient to chronic stress and now our research has found the reason why," Yan said.
The research showed that in rats exposed to repeated episodes of stress, females respond better than males because of the protective effect of estrogen.
In the UB study, young female rats exposed to one week of periodic physical restraint stress showed no impairment in their ability to remember and recognise objects they had previously been shown.
In contrast, young males exposed to the same stress were impaired in their short-term memory.
An impairment in the ability to correctly remember a familiar object signifies some disturbance in the signalling ability of the glutamate receptor in the prefrontal cortex, the brain region that controls working memory, attention, decision-making, emotion and other high-level "executive" processes.
Last year, Yan and colleagues published in journal Neuron a paper showing that repeated stress results in loss of the glutamate receptor in the prefrontal cortex of young males.
The new study shows that the glutamate receptor in the prefrontal cortex of stressed females is intact.
The findings provide more support for a growing body of research demonstrating that the glutamate receptor is the molecular target of stress, which mediates the stress response, according to the study in the journal Molecular Psychiatry.
The stressors used in the experiments mimic challenging and stressful, but not dangerous, experiences that humans face, such as those causing frustration and feelings of being under pressure, Yan said.
By manipulating the amount of estrogen produced in the brain, the UB researchers were able to make the males respond to stress more like females and the females respond more like males.
"When estrogen signalling in the brains of females was blocked, stress exhibited detrimental effects on them. When estrogen signalling was activated in males, the detrimental effects of stress were blocked," Yan said.
"We still found the protective effect of estrogen in female rats whose ovaries were removed. It suggests that it might be estrogen produced in the brain that protects against the detrimental effects of stress," Yan said.