Lead exposure impairs the NMDA agonist-induced NOS expression in pyramidal hippocampal cells

Chronic exposure to lead (pb) affects neural function s in central nervous system (cns)particularly the learning and memory. on the other hand, alteration of calcium level in the cnsresults in activation of nos. it has been shown that lead enters the neurons through calciumchannels and displa ces ca2+ from calcium binding proteins such as calmodulin and troponin cthereby affecting calcium-mediated processes.our recently data showed that no prodaction due to nmda receptor simulation in culturedca1 pyramidal cells has been diminished in the presence of 10 nm of lead acetate. therefore,it is possible that lead can inhibit the elevation ofno through blockade ofnmda receptor andinterference of ltp through this mechani sm. this finding may attribute to the effect of lead onthe nos activi ty or expression as key enzyme producing no. in this study we have examinedthe effect of lead acetate on the nos expression in the presence of nmda agon ist usingimmunocytochemical analysis. expression of nnos were examined in the ca1 pyramidalcells exposed to 10 and 100 nm lead acetate and 40 flm acbd (nmda agoni st). the result ofthis experiment showed that the enhanced nnos expression induced by acbd significantlydiminished by lead acetate. the trend of this inhibition is similar to amount ofno productionindicating that the decrease of expre ssion may major reason of decrease in no production.