The action of thallium on the excitability of CA1 pyramidal cells in hippocampal slices.
The effect of thallium ions on central neuronal activity was investigated in hippocampal slice preparations from guinea pigs and rats using extra- and intracellular recording techniques. Thallium induced a reversible and concentration-dependent reduction of the orthodromically evoked compound action potential of CA1 pyramidal cells with only weak effects on either afferent fiber activity, postsynaptic potentials or antidromically evoked responses. The membrane potential and input resistance of the pyramidal cells were not impaired by thallium. In contrast, variations in the maintained spike activity and spontaneously occurring inhibitory postsynaptic potentials were observed. It is concluded, that in contrast to its presynaptic action in the peripheral nervous system, thallium has a predominant postsynaptic target site in the hippocampal slice preparation. It is suggested that the neurotoxic action of thallium is not mediated by an interaction with specific ion channels of the cell membrane, but rather by an unspecific influence on the intracellular metabolism of the CA1 pyramidal cell.
Lohmann
H
H
Medical Institute of Environmental Hygiene, Heinrich-Heine-University Düsseldorf, Department of Neurotoxicology, FRG.
Csicsaky
M
M
Wiegand
H
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects* / Q000503:physiopathology; D066298:In Vitro Techniques; D051381:Rats; D013569:Synapses / Q000187:drug effects; D013793:Thallium / Q000494:pharmacology*
D013793:Thallium