17beta-estradiol effect on the extracellular concentration of amino acids in the glutamate excitotoxicity model in the rat.
Estrogen has demonstrated a neuroprotective role in a rat model of glutamate excitotoxicity and other neurodegenerative disorders. We studied the effect of 17beta-estradiol on glutamate-induced increases in amino acids levels (aspartate, histidine, taurine and GABA) in the rat cortex. Local perfusion of glutamate produced a transient increase of aspartate, histidine, taurine and GABA in the extracellular fluid. Pretreatment with 17beta-estradiol significantly reduced the increases of taurine and moderately attenuated that of histidine, whereas aspartate and GABA releases were not modified. The effect of 17beta-estradiol on histidine release was reversed by the antiestrogen tamoxifen, suggesting a receptor-dependent mechanism. Good correlations between the volumes of the glutamate-induced lesions and the extracellular concentrations of taurine and aspartate were observed. These findings suggest that the attenuation of the glutamate-induced release of taurine by 17beta-estradiol may participate in the neuroprotective effects of 17beta-estradiol and that increased levels of aspartate and taurine are markers for the severity of the glutamate-induced cortical lesions.
Ritz
Marie-Françoise
MF
Neurosurgery Laboratory, Pharmazentrum, Easel, Switzerland. Marie-Francoise.Ritz@unibas.ch
Schmidt
Petra
P
Mendelowitsch
Aminadav
A
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D018698:Glutamic Acid / Q000633:toxicity*; D007150:Immunohistochemistry; D008297:Male; D017551:Microdialysis; D051381:Rats; D017208:Rats, Wistar
D000596:Amino Acids; D018698:Glutamic Acid; D004958:Estradiol