Halothane blocks synaptic excitation of inhibitory interneurons.
BACKGROUND
Activation of principal hippocampal neurons is controlled by feedforward and feedback inhibition mediated by gamma-aminobutyric acidergic interneurons. The effects of halothane on glutamate receptor-mediated synaptic excitation of inhibitory interneurons have not been reported yet.


METHODS
The effects of halothane on glutamatergic excitatory postsynaptic currents and on spike threshold in visually identified interneurons were studied with tight-seal, whole-cell voltage- and current-clamp recordings in thin slices from adult mouse hippocampus. The excitatory postsynaptic currents were pharmacologically isolated into their N-methyl-D-aspartate and non-N-methyl-D-aspartate receptor-mediated components using selective antagonists.


RESULTS
Halothane (0.37-2.78 mM) reversibly blocked non-N-methyl-D-aspartate and N-methyl-D-aspartate excitatory postsynaptic currents in hippocampal oriens-alveus interneurons. Half-maximal inhibition was observed at similar concentrations (0.59 mM and 0.50 mM, respectively). Halothane inhibited synaptically generated action potentials at concentrations that did not elevate the spike threshold.


CONCLUSIONS
Halothane blocks glutamate receptor-mediated synaptic activation of inhibitory interneurons in the mouse hippocampus.
Perouansky
M
M
Department of Physiology, Hebrew University School of Medicine, Jerusalem, Israel.
Kirson
E D
ED
Yaari
Y
Y
D000200:Action Potentials / Q000187:drug effects; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D004558:Electric Stimulation; D006221:Halothane / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects; D007395:Interneurons / Q000187:drug effects*; D051379:Mice; D018408:Patch-Clamp Techniques; D017470:Receptors, Glutamate / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects
D018685:Anesthetics, Inhalation; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D006221:Halothane