Ovaries are the main producers of oestrogen but when they give out, the brain in monkeys can take over in making the hormone.

Ei Terasawa and her colleagues at the University of Wisconsin in Madison removed the ovaries of female rhesus monkeys (Macaca mulatta) and briefly stimulated the animals' brains with oestrogen or an electrical current. The brain's hypothalamus region began producing its own oestrogen, along with other hormones involved in reproduction.

If human brains have the same capability, targeting this oestrogen source could be a way to treat diseases such as depression that may be linked to oestrogen imbalances, the authors say.

J. Neurosci. 33, 19051–19059 (2013)