How do sex hormones define the brain differences between men and women?

A region in the mouse brain, called the bed nucleus of the stria terminalis, is larger in males than females

Sex hormones play an important role in shaping animal behavior, and their effects start early

There are hundreds of genes in the brain that are controlled by estrogen

Cold Spring Harbor Laboratory assistant professor Jessica Tollkuhn, graduate student Bruno Gegenhuber and their colleagues have precisely mapped where the estrogen receptor binds to DNA within mouse brain cells

Estrogen is present in both male and female brains, Tollkuhn explained: some neurons themselves produce estrogen from testosterone

"This is a critical period of brain development and connectivity, and in order for it to have permanent changes in brain connectivity, it has to get these inputs

Tollkuhn's team looked at the location of estrogen receptors after a hormonal surge, concentrated in a brain region called the bed nucleus of the stria terminalis, which is larger in males than females in mice and humans

Now that they know the genes for estrogen's role in the brain, Tollkuhn's team plans to explore how these genes regulate the hormone's different effects on brain development, behavior and disease

Reference: "Epigenetic regulation of brain sexual differentiation by estrogen receptor alpha" by B.