Differential modulation by dopamine of responses evoked by excitatory amino acids in human cortex

Autor: Michael Levine, Warwick J. Peacock, Carlos Cepeda, Zivotije Radisavljevic, Nathaniel A. Buchwald
Rok vydání: 1992
Předmět:
Zdroj: Synapse. 11:330-341
ISSN: 1098-2396
0887-4476
DOI: 10.1002/syn.890110408
Popis: The responses of human neocortical neurons to iontophoretic application of excitatory amino acids and their modulation by dopamine (DA) were studied in vitro. Brain slices were obtained from children undergoing surgery for intractable epilepsy. Application of N-methyl-D-aspartate (NMDA) to the slices induced slow depolarizations accompanied by decreased input conductances and sustained action potentials in cortical neurons. Glutamate produced rapid depolarizations and firing with few changes in input conductances. Quisqualate also induced depolarization and firing, but input conductances increased during the rising phase of the membrane depolarization. Iontophoretic application of DA alone produced no change in membrane potential or input conductance. However, when DA was applied in conjunction with the excitatory amino acids, it produced contrasting effects. With either bath application of DA or when iontophoresis of DA preceded application of NMDA, the amplitude of the membrane depolarizations and the number of action potentials were increased, whereas the latency of these responses decreased. In contrast, DA decreased the amplitude of the depolarizations and the number of action potentials evoked by glutamate or quisqualate. The fact that DA affects responses to NMDA and glutamate or quisqualate in opposite directions is of considerable importance to the understanding of cellular mechanisms of neuromodulation and the role of DA in cognitive processing and in epilepsy. © Wiley-Liss, Inc.
Databáze: OpenAIRE
Externí odkaz: