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Sex cells

“A hormone that generates new brain cells after sex could be the key to stroke recovery”, says the Calgary Herald (3 January 2003). This was the response to the publication of work by the team of Samuel Weiss at the University of Calgary, showing that prolactin, a hormone that is released after sexual intercourse and also during pregnancy and breastfeeding, can stimulate the production of new neurons in the mouse olfactory bulb.

This finding might explain why women have a heightened sense of smell during pregnancy, and the researchers also suggest that the brain might put the new neurons to other uses. Weiss explained “The importance of it, beyond the basic biology of stem cells, is the fact that prolactin may be an important neurogenic molecule that may have significant potential for generating new brain cells” (The Globe and Mail, Canada, 2 January 2003).

Using animal models, the team are investigating the possibility that prolactin could be administered immediately after a stroke to encourage the brain to repair itself. Weiss said “We have exciting preliminary data suggesting that the new stem cell-generated brain cells can be redirected to parts of the rodent brain that are damaged after a stroke and this results in partial improvement of the animal's ability to move its limbs” (Calgary Herald, 3 January 2003).

As yet, there is no evidence that prolactin can boost the brain power of healthy individuals. However, the press did not allow this fact to get in the way of a saucy headline or two, as The Globe and Mail proved with “Sex makes your brain grow” (2 January) and “A roll in the hay is good for the brain, new research shows” (3 January).


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Wood, H. Sex cells. Nat Rev Neurosci 4, 88 (2003).

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