March 15, 2010
I previously detailed 3 well-described patterns of catamenial symptoms that women report: Type 1 – premenstrual, Type 2 – peri-ovulatory (mid-cycle), and Type 3 – luteal (throughout the 2 weeks from midcycle to menses). Here I want to describe how and why the two reproductive hormones, estrogen (E2) and progesterone (P), have a yin / yang effect on the brain, so that these 3 patterns make sense.
Firstly, these hormones cause changes in our emotions and brain functioning by binding to specific docking sites (receptors) on specific brain cells in specific areas of the brain. Estrogen is the yin. When estrogen binds to its receptor on a brain cell, the brain cell fires faster and can use more glucose (sugar) and oxygen , its main fuels, faster. Estrogen also increases the flow of blood to the brain cell so more fuel can be delivered faster. These and many other similar effects make estrogen an energizing, mood elevating, “upper” hormone. However, too much of a good thing is a problem here also, since too much estrogen effect (“unopposed” by progesterone) can bring anxiety, agitation and even seizures.
Progesterone is the yang. It causes powerful restraints on a brain cell’s activity and firing rates and also decreases the number of estrogen receptors on the cell, therefore directly blocking estrogen’s effects. These and many other related effects give progesterone calming, relaxing, anti-seizure even tranquilizing properties. But, like we see in alcohol withdrawal (irritability, agitation, seizures), sudden withdrawal of progesterone can bring the same troubling symptoms.