Association of serum estrogen level and ischemic neuroprotection in femalerats

Estrogen-related ischemic neuroprotection has been documented in male and o variectomized female rats. The precise molecular mechanism underlying estro gen's neuroprotective effect remains obscure. In the present study, we exam ined whether endogenous estrogen levels affect post-ischemic outcomes in no rmal cycling female rats. Occlusion of both the common carotid arteries and the right middle cerebral artery (1.5 h) followed by reperfusion (24 h) ca used cortical infarction, increased neutrophil accumulation, and elevated a ntioxidant enzyme and lactate dehydrogenase activities. These post-ischemic changes varied in the female rats and were inversely correlated with circu lating estrogen levels. More severe post-ischemic changes and injury accomp anied the decline in circulating estrogen levels in normal cycling female r ats, indicating that estrogen is probably the major hormonal player in fema le resistance to ischemia. (C) 2001 Elsevier Science Ireland Ltd. All right s reserved.