L-pyroglutamic acid protects rat cortical neurons against sodium glutamate-induced injury

AIM: To evaluate the effects of L-pyroglutamic acid (L-PGA, L-5-oxo-2-pyrro lidinecaroxylic acid) on sodium glutamate-induced neurotoxicity in rat cort ical neurons. METHODS: In primary cortical cultures from 16-d-old fetal rat , neuronal viability and contents of nitrite in the bathing medium after tr ansient exposure to sodium glutamate (Glu) were measured; with Fura 2-AM as an intracellular calcium indicator, AR-CM-MIC cation measurement system wa s used to examine cytosolic free calcium ([Ca2+](i)). RESULTS: L-PGA 10 - 8 0 mu mol.L-1, inhibited Glu (500 mu mol. L-1)-induced neuronal loss in a co ncentration dependent manner with IC50 value of (41 +/- 9) mu mol. L-1(95 % confidence limits: 30.3 - 54.7 mu mol. L-PGA also attenuated Glu-induced N O release. L-PGA 1, 3, 10, 30, and 100 mu mol.L-1 depressed Glu-caused [Ca2 +](i) elevation by 20.5 %, 34.4 %, 47.7 %, 70.6 %, and 80.4 %, respectively . CONCLUSION: L-PGA protects cortical neurons against Glu-induced neurotoxi ty which may be related to inhibition of NO formation or suppression of the rise in [Ca2+](i).