Effects of microiontophoretically applied flurazepam on responses of cerebral cortical neurones to putative neurotransmitters

Canadian Journal of Physiology and Pharmacology
J N Nestoros, A Nistri

Abstract

Utilizing standard microiontophoretic techniques and recording extracellularly in cats, we studied the effects of flurazepam, a water-soluble benzodiazepine, on the spike activity of single cerebral neurones and its interactions with several excitatory and inhibitory putative neurotransmitters. Large iontophoretic doses (5--30 nA, 0.1 M solution) of flurazepam induced a depression of spike amplitude. Smaller doses (less than 5 nA, 0.1 M solution or 20--50 nA, 20 mM in 0.16 M NaCl) reduced the excitation produced by glutamate, aspartate, and homocysteate, but antagonism of acetylcholine-evoked excitations required large flurazepam doses (up to 30 nA, 0.1 M solution). Even lower doses of flurazepam (less than 10 nA, 20 mM in 0.16 M NaCl) enhanced the inhibitory effect of gamma-aminobutyric acid (GABA) but antagonized that of 5-hydroxytryptamine, and had no effect on dopamine-induced inhibition of firing. Hence, only GABA-evoked inhibitions were significantly potentiated by flurazepam. These results demonstrate the multiple possible interactions between a benzodiazepine and different putative neurotransmitters in the mammalian cerebral cortex.

References

Apr 1, 1987·Pharmacology, Biochemistry, and Behavior·M Denavit-SaubiéS F Gonsalves
Jan 1, 1982·General Pharmacology·J G SinclairD P Harris
Aug 11, 1981·Molecular and Cellular Biochemistry·P Krogsgaard-Larsen, E Falch
Oct 1, 1984·Canadian Journal of Psychiatry. Revue Canadienne De Psychiatrie·J N Nestoros

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