RNAi-mediated silencing of estrogen receptor in the ventromedial nucleus of hypothalamus abolishes female sexual behaviors

Estrogen receptor alpha (ER alpha) plays a major role in the regulation of neuroendocrine functions and behaviors by estrogens. Although the generation of ER alpha knockout mice advanced our knowledge of ER alpha functions, gene deletion using this method is global and potentially confounded by developmental consequences. To achieve a site-specific knockdown of ER alpha in the normally developed adult brain, we have generated an adeno-associated virus vector expressing a small hairpin RNA targeting ER alpha. After bilateral injection of this vector into the hypothalamic ventromedial nucleus in ovariectomized female mice, expression levels of ER alpha as well as the estrogen-inducible progesterone receptor were profoundly reduced despite the continued presence of this receptor elsewhere in the brain. Functionally, silencing of ER alpha in the ventromedial nucleus abolished female proceptive and receptive sexual behaviors while enhancing rejection behavior. These results provide evidence that adeno-associated virus-mediated long-term knockdown of genes can be used to delineate their effects on complex behaviors in discrete brain regions.