Glutamate preconditioning prevents neuronal death induced by combined oxygen-glucose deprivation in cultured cortical neurons

The study of ischemic tolerance is critical in the development of strategies for the treatment of ischemic stroke. We used the oxygen and glucose deprivation (OGD) paradigm in cultured cortical neurons as an in vitro approach to elucidate the mechanism of protection conferred by glutamate preconditioning. Pretreatment of neurons with N-methyl-D-aspartate (NMDA) receptor antagonists prevented OGD-induced cell death whereas a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor and voltagedependent Ca" channel (VDCC) blockers were without effect. Neurons preconditioned with glutarnate exhibited resistant to damage induced by OGD. The ischernic tolerance depended on the duration of preconditioning exposure and the interval between preconditioning exposure and test challenge. Protective efficacy was blocked by the NMDA or AMPA receptor antagonists but not by the VDCC blocker. Furthermore, neuroprotective effect was not seen if extracellular Ca" was ornitted Or removed with EGTA. Pretreatment with staurosporin and 2-IN-(2-hydroxyethyl)1-N-(4-methoxybenzenesulfonyl)1 amino-N-(4-chlorocinnamyl)-N-methylbenzylamine (KN93) but not 2-(4-MOFpholinyl)-8-plienyl-1(4H)-beiizopyran-4-one (LY294002) or 1,4-diamino-2,3-dicyano-1, 4-bis[2-aminophenylthiol butadiene (UO126) significantly reduced ischemic tolerance. Preconditioning increased phosphorylated levels ofcAMP responsive element binding protein (CREB) and pretreatment with CRE-clecoy oligonuclectide completely blocked preconditioning-induced increase in cell viability. Importantly, glutamate preconditioning increased l3cl-2 expression that was blocked by KN93' staurosporin and CRE-decoy oligonucleoticle. These results suggest that preconditioning with glutamate conferred neUroprotection against subsequent OGD by inducing p-CREB-mediated Bcl-2 expression. (C) 2008 Elsevier B.V. All rights reserved.