August 20, 2010
Stress Hormone Receptors Less Adaptive in Female Brain
Time: 00:03:14 | Size: 2.99 MB
Speaker: Dr. Rita Valentino
Description: Dr. Rita Valentino describes a discovery in rat brains that may explain why women are more prone than men to mood and anxiety disorders.
Announcer: NIMH Radio from Bethesda.
Dr. Rita Valentino: The incidents of depression, anxiety and many disorders- psychiatric disorders that in which stress has been implicated, are more prevalent in females than males and I think, particularly for depression, it’s almost twice as high in females compared to males.
Announcer: Doctor Rita Valentino is a neuroscientist at the University of Pennsylvania. With funding from the National Institute of Mental Health, Dr. Valentino and colleague Dr. Deborah Bangasser have discovered in rats a striking sex difference in the bran’s stress response. Valentino says that could explain why women are twice as prone to mood and anxiety disorders than men. They showed that brain cells in male rats can adapt to the stress hormone corticotropin releasing factor, or CRF, in a way cells in the female brain cannot. For CRF to produce its effects on cells, it has to bind to a protein on the cell surface known as a receptor. Dr. Valentino says that receptor behaves differently in response to stress in the brains of male rats.
Dr. Rita Valentino: The receptor for CRF that was on the cell surface becomes internalized into the cell. And that’s an adaptive mechanism, because the CRF that’s on the outside of the cell can no longer bind to it. This occurred in male rats. This internalization process, this bringing-in of the receptor after animals were stressed, was not happening in females. Those cells would then not be able to adapt to excess CRF. Hypersecretion of CRF has been proposed to occur in depression.
Announcer: Valentino’s research also suggests the female brain in rats could be at a disadvantage in stressful situations.
Dr. Rita Valentino: After an animal has been exposed to stress, the adaptive mechanism for curbing the response -- or restraining the response to too much CRF -- is compromised in females…some modification to the receptor that happens after it’s made that may be going on in females and not in males.
Announcer: The new findings fit with evidence that the brain is, in essence, high-jacked by a runaway stress response in disorders like depression.
Dr. Rita Valentino: We have a stress response because it helps us survive. If we didn’t have it, we wouldn’t be able to survive. It’s an adaptive mechanism for us to deal with life-threatening challenges. It becomes maladaptive or pathologic when it is turned on inappropriately, in the absence of any life-threatening challenge -- or when it extends, or persists beyond when the life-threatening challenge is terminated.
Announcer: Dr. Rita Valentino on NIMH Radio.