Risk of hormone replacement therapy in stroke patients

17β-estradiol attenuates breakdown of blood-brain barrier and hemorrhagic transformation induced by tissue plasminogen activator in cerebral ischemia

Tissue plasminogen activator (tPA) remains the only approved thrombolytic agent for the early treatment of ischemic stroke. However, treatment with tPA may lead to disruption of the blood-brain barrier and hemorrhagic transformation. 17β-estradiol (E2) has demonstrated efficacy in reduction of infarct volume in ischemic stroke models. The effects of acute administration of E2 on permeability of the blood-brain barrier and its ability to prevent hemorrhagic transformation in ischemic rats treated with tPA have not previously been studied. Here, we show that neurological deficits, brain water content, and Evan's blue extravasation were increased in ovariectomized female Wistar rats treated with tPA and attenuated in rats receiving E2+tPA. We also show that intracerebral hemoglobin and matrix metalloproteinase-9 activity were elevated with tPA treatment, and these increases were reduced by E2 treatment. Taken together, these data demonstrate that acute administration of E2 is capable of ameliorating some of the adverse effects of tPA administration, including the increase of matrix metalloproteinase-9 activity, blood-brain barrier permeability, and hemorrhagic transformation. These findings suggest a potential role for estrogen in thrombolytic treatment for ischemic stroke.

Cerebral embolism and hormone replacement therapy

Few studies have focused on the relationship between hormone replacement therapy (HRT) for postmenopausal women or those with breast cancer and the occurrence of cerebral embolism. Results are conflicting as to whether there is a link between the two. We describe three patients who experienced cerebral embolism during HRT. A 73-year-old woman had a transient ischemic attack (TIA) 6 years prior to the present admission. She then took HRT oestrogen plus medroxyprogesterone acetate for about 6 years. The HRT had been prescribed by a gynaecologist for amelioration of postmenopausal symptoms. Six years after beginning HRT, she experienced sudden onset left hemiparesis due to cerebral embolism. Two other patients had been taking HRT for breast cancers. One, a 47-year-old woman, had taken medroxyprogesterone acetate for more than one year, for recurrence of breast cancer. She had developed sudden complete left hemiparesis due to an embolism at the carotid bifurcation. The other patient, a 72-year-old woman who was taking tamoxifen citrate for prevention of breast cancer relapse, experienced cerebral embolism just 2 months after beginning tamoxifen. The risk of cerebral embolism in those on HRT should be emphasized, along with the beneficial effects in terms of postmenopausal symptoms and prevention of breast cancer recurrence.