FEMALE mice that refuse to mate have provided a clue to just which part of the brain determines sexual desire in women.
Sonoko Ogawa of the University of Tsukuba in Japan and her colleagues in the US used a harmless virus to shuttle fragments of genetic material called small hairpin RNAs into the area of the brain known as the ventromedial nucleus (VMN), which is sited in the hypothalamus. The RNA was designed to block a receptor for the hormone oestrogen. These receptors are found in other parts of the body too, but by delivering the RNA in this way Ogawa and her colleagues could be sure that only those in the VMN were being blocked.
The effect was dramatic. The females refused to have sex. 鈥淭hey became extremely aggressive towards males, and started biting and kicking when males approached,鈥� Ogawa says. None of the females showed the usual signs of sexual receptivity, and they all refused to mate (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0603045103).
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Disruption of oestrogen signalling in this region is sufficient to completely block normal female courtship behaviour, Ogawa says. She adds that the VMN has long been suspected to be the seat of female desire, but that this is the first time it has been shown unambiguously. The work also confirms that oestrogen is vital for arousal. Next, she plans to use the same technique to look at male behaviour.
