17 beta-estradiol protects neurons from ischemic damage and attenuates accumulation of extracellular excitatory amino acids.

We studied the effect of 17 beta-estradiol on ischemia-induced increases in extracellular amino acids (aspartate, glutamate, glycine, and taurine) in the gerbil hippocampal CA1 region by a microdialysis-high-performance liquid chromatography system in vivo. Transient forebrain ischemia for 3 min produced a marked accumulation of aspartate, glutamate, taurine, and glycine (498%, 410%, 266%, and 178%, respectively). 17 beta-estradiol reduced the increase of aspartate and glutamate by 57% and 53% of the peak values. This finding suggests that 17 beta-estradiol may protect neurons against ischemic damage by attenuating the ischemia-induced increase in extracellular excitatory amino acids.