Scientific research shows that women are twice as likely as men to develop stress disorders. Why are women more sensitive than men to stress? A recent research study presents new evidence that estrogen could play a role.
The symptoms of disorders like major depressive disorder and post traumatic stress disorder lead neuroscientists to speculate that a dysfunction occurs in the way the medial prefrontal cortex connects to the amygdala–regions of the brain associated with the regulation of memory and behavior. Following research published in 2009 determining resilience against changes in dendritic morphology in this region in male rats, scientists at the Mount Sinai School of Medicine turned their focus to female rats. They discovered unexpected changes in dendritic length and spine density to the neurons in this region when both estrogen and stress are present.
After removing the ovaries from all subjects and implanting half of the rats with estrogen, the researchers exposed them to ten days of either immobilization stress (two hours in a rodent immobilization bag) or home cage rest. They then sectioned the rats’ brains and examined the neurons in question.
“We used Neurolucida and Neurolucida Explorer to measure dendritic length and branch point number in a set of pyramidal neurons that had been filled with the fluorescent dye Lucifer Yellow,” said lead author Dr. Rebecca Shansky. “The software was very user-friendly, and we were easily able to customize the settings to get just the analyses we wanted,” Dr. Shansky added.
What they found was increased dendritic arborization and spine density in the females treated with estrogen, “indicating that estrogen and stress can interact at the level of this circuit to produce a unique response to stress in females,” according to the paper “Estrogen Promotes Stress Sensitivity in a Prefrontal Cortex–Amygdala Pathway,” published earlier this year in Cerebral Cortex.
Read the free abstract, or download the full paper at Cerebral Cortex.
Rebecca M. Shansky, Carine Hamo, Patrick R. Hof, Wendy Lou, Bruce S. McEwen, and John H. Morrison, “Estrogen Promotes Stress Sensitivity in a Prefrontal Cortex–Amygdala Pathway” (Cereb Cortex 2010; 20: 2560-2567)