NMDA RECEPTOR ACTIVITY AND ITS MODULATION BY SULFHYDRYL COMPOUNDS: CHEMILUMINESCENCE MEASUREMENTS IN RAT BRAIN CORTICAL SYNAPTOSOMES

Authors : Belgin KÜÇÜKKAYA, Goncagül HAKLAR, Süha YALÇIN

Pages : 70-73

View : 17 | Download : 8

Publication Date : 2016-12-03

Article Type : Research Paper

Abstract :Objective: We have used chemiluminescence insert ignore into journalissuearticles values(CL); measurements to investigate the effect of modulatory compounds on N-methyl-D-aspartate insert ignore into journalissuearticles values(NMDA); receptor activity in rat brain frontal cortex synaptosomes. Methods: Freshly prepared synaptosomes insert ignore into journalissuearticles values(protein concentration: 5 mg/mL); were incubated with different modulatory molecules such as Zn++ insert ignore into journalissuearticles values(1 mM);, Cd++ insert ignore into journalissuearticles values(1 mM);, reduced glutathione, insert ignore into journalissuearticles values(GSH); insert ignore into journalissuearticles values(1 mM, 10 mM);, oxidized glutathione insert ignore into journalissuearticles values(GSSG); insert ignore into journalissuearticles values(1 mM, 5 mM);, dithiothreitol insert ignore into journalissuearticles values(DTT); insert ignore into journalissuearticles values(1 mM, 10 mM); and N- ethylmaleimide insert ignore into journalissuearticles values(NEM); insert ignore into journalissuearticles values(1 mM, 10 mM); for 5 minutes at room temperature. After preincubation, 0.1 mM NMDA was added either alone or in the presence of 65 mM KCI. CL measurements were taken with lucigenin as enhancer, at 10 second intervals for 1 minute. Results: Synaptosomes showed a marked increase in CL upon addition of NMDA both in the presence and absence of KCI. When preincubated with the noncompetitive NMDA receptor antagonist insert ignore into journalissuearticles values(Zn++); or with the calcium channel blockerinsert ignore into journalissuearticles values(Cd++);, CL formation was suppressed. DTT, a strong sulfhydryl group reducing agent, increased the activity of NMDA receptor, whereas NEM, a sulfhydryl group alkylating agent, decreased the NMDA receptor activity. Reduced and oxidized forms of glutathione decreased the receptor activity and were protective under excitotoxicity and depolarization conditions. Conclusion: Our results demonstrated that endogenous and exogenous sulfhydryl compounds affect the redox modulatory site and play important roles in the generation of reactive oxygen species after activation of the NMDA receptor. Key Words: Chemiluminescence; Cortical synaptosomes; Excitotoxicity; NMDA receptor; Sulfhydryl group modulators
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