Interaction between metals and chelating agents affects glutamate binding on brain synaptic membranes.
The present study investigates the possible effects of Hg2+, Pb2+, and Cd2+ on [3H]-glutamate binding. To better understand the role of the thiol-disulfide status on the toxicity of such metals toward glutamatergic neurotransmission, we used three thiol chelating agents, 2,3-dimercaptopropanol (BAL), 2,3-dimercaptopropane 1-sulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (DMSA). Dithiotreitol (DTT) was tested for its ability to prevent metals-induced inhibition on [3H]-glutamate binding. Hg2+, Pb2+, and Cd2+ showed a concentration-dependent inhibition on [3H]-glutamate binding, and mercury was the most effective inhibitor. BAL did not prevent [3H]-glutamate binding inhibition by Hg2+, Cd2+, and Pb2+. However, DMPS and DMSA prevented the inhibition caused by Cd2+ and Pb2+, but not by Hg2+. DTT did not prevent the inhibition on [3H]-glutamate binding caused by 10 microM Hg2+. In contrast, it was able to partially prevent [3H]-glutamate binding inhibition caused by 40 microM Pb2+ and Cd2+. These results demonstrated that the heavy metals present an inhibitory effect on [3H]-glutamate binding. In addition, BAL was less effective to protect [3H]-glutamate binding inhibition caused by these metals than other chelating agents studied.
Soares
Félix Antunes
FA
Departamento de Bioquimica, ICBS, Universidade Federal do Rio Grande do Sul, RS, Brazil.
Farina
Marcelo
M
Santos
Francielli Weber
FW
Souza
Diogo
D
Rocha
João Batista Teixeira
JB
Nogueira
Cristina Wayne
CW
D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002614:Chelating Agents / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013570:Synaptic Membranes / Q000378:metabolism*; D014316:Tritium
D002614:Chelating Agents; D008670:Metals; D014316:Tritium; D018698:Glutamic Acid