Intriguingly, brain aromatase levels were shown to increase in astrocytes in the peri-infarct area following MCAO, which may facilitate survival of neurons following the insult [38]. As a whole, these findings emphasize the importance of gonadal-derived circulating estrogen in protecting the brain against ischemic insult. They also support a potential role as well for brain-derived estrogen synthesis in neuroprotection, as evidenced by the finding that ischemic brain injury was smaller in ovariectomized wild-type animals than in aromatase knockout mice [36], and that aromatase expression increases in the peri-infarct area following cerebral ischemia [38].