Estrogen-Mediated Neuroprotection After Experimental Stroke in Male Rats

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Abstract
Background and Purpose—We have previously shown that 17β-estradiol reduces infarction volume in female rats. The present study determined whether single injection or chronic implantation of estrogen confers neuroprotection in male animals with middle cerebral artery occlusion (MCAO) and whether there is an interaction with endogenous testosterone. Methods—Male Wistar rats were treated with 2 hours of reversible MCAO. In protocol 1, acute versus chronic estrogen administration was examined in groups receiving the following: Premarin (USP) 1 mg/kg IV, immediately before MCAO (Acute, n=13, plasma estradiol=171±51 pg/mL); 7 days of 25 μg (E25, n=10, 10±3 pg/mL) or 100 μg 17β-estradiol (E100, n=12, 69±20 pg/mL) by subcutaneous implant; or saline (SAL, n=21, 3±1 pg/mL). Laser-Doppler flowmetry was used to monitor the ipsilateral parietal cortex throughout the ischemic period and early reperfusion. At 22 hours of reperfusion, infarction volume was determined by 0 2,3,5-triphenyltetrazolium chloride staining and ...