RNAi ? a new targeted silencer?

For the first time, researchers have used RNA interference (RNAi) to genetically silence estrogen's effects in a specific part of the mouse brain, rather than throughout the entire body. The technique, reported online June 26 in the Proceedings of the National Academy of Sciences, led to striking changes in female sexual behavior, and could help scientists map brain circuitry, according to the authors.The results show that RNAi "can really help map out the genes and neural networks behind complex behaviors," co-author Sonoko Ogawa at Rockefeller University in New York told The Scientist.In the past, scientists have generated female mice that completely lack estrogen receptors alpha or beta. Estrogen receptor alpha knockout mice aggressively reject male advances; beta knockout mice, in contrast, exhibit normal sexual behavior.Experiments using global knockout mice can't distinguish between the effects of estrogen in adulthood and earlier in development, according to study co-author...