title: Regional differences in the depressant effects of midazolam on excitatory synaptic transmission in the rat hippocampus.
abstract: The effects of midazolam, one of the most popular benzodiazepines, was examined on excitatory synaptic transmission in the hippocampus. Both CA1 pyramidal cells (CA1-PCs) and dentate gyrus granule cells (DG-GCs) were studied in rat hippocampal slices with extracellular recordings. Midazolam depressed the amplitudes of orthodromic population spikes (O-PS) and excitatory postsynaptic potential (EPSP) slopes of CA1-PCs in a dose-dependent manner, but depressed those of DG-GCs to a lesser extent. On the other hand, midazolam had little effect on the amplitudes of antidromic population spikes of both CA1-PCs and DG-GCs. A GABAA receptor antagonist bicuculline strongly antagonized the depressant effects of 75 microM midazolam on the amplitudes of O-PS by 73% in CA1-PCs, whereas it did not antagonize the effects of midazolam in DG-GCs. These results suggest that the differential effects of midazolam could be due to the different types and/or density of GABAA receptors between CA1-PCs and DG-GCs.
authors.affiliation: Department of Physiology, Sapporo Medical University School of Medicine, Japan. sato@serpent.cc.sapmed.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Aoki
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D018891:Dentate Gyrus / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D018757:GABA Modulators / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects*; D008297:Male; D008874:Midazolam / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D018756:GABA Antagonists; D018757:GABA Modulators; D008874:Midazolam; D001640:Bicuculline