E2 given intraventricularly affords neuroprotection in aged female rats 6 months after OVX.

<p>Aged female rats were subjected to sham surgery or global ischemia 6 months after OVX. Panel A: Surviving CA1 pyramidal neurons were counted bilaterally in 3 sectors (250 µm×250 µm each) of 4 sections of the dorsal hippocampus (top left). Representative photomicrographs of neurons in dorsal CA1 one week after sham or ischemia (Isch) surgery in rats infused immediately with vehicle (veh) or 2.25 µg of E2. <i>Scale bars,</i> 60 µm. SO, stratum oriens; SP, stratum pyramidale; SR, stratum radiatum. Panel B: Surviving pyramidal neurons in the CA1 subfield of the hippocampus were quantified 7 days after ischemia. Because there were no significant differences in cell counts in vehicle (black circles) and E2 (gray circles) treated sham rats, data were combined and shown as a single sham group. Data are means ± SEM and represent the grand sum of neurons in all 3 counting sectors from all 4 sections. ***, <i>p<</i>0.001 versus ischemia; **, <i>p<</i>0.01 versus ischemia/vehicle.