title: Inhibition of GABA and glycine responses by glutamate in rat hippocampal neurons.
abstract: Currents elicited by activation of GABAA, glycine (GLY) and glutamate (GLU) receptors (R) in pyramidal neurons of CA1 region from thin slices of rat hippocampus were studied using the tight-seal whole-cell recording techniques. GLU (100 mM) induced a long-lasting depression of GABA- and GLY-activated currents (IGABA and IGLY) when using standard saline in conjunction with depolarization. The long-lasting depression was not observed: (1) in neurons held at -70 mV during GLU application; (2) in neurons depolarized by current injection but not exposed to GLU; (3) when GLU/depolarization protocol was performed in Ca(2+)-free medium; or (4) by using recording patch-pipettes filled with a medium that tightly controlled cytosolic Ca2+ transients. Sphingosine (10 mM), staurosporine (1 mM) and the specific inhibitor of protein kinase C (PKC(19-36) (200 mM in the patch-pipette solution), blocked the long-lasting depression of IGABA. IGABA was depressed even when the treatment with GLU was performed before patch-clamping the neuron. We conclude that the sustained IGABA and IGLY depression is mediated by cytosolic events triggered by the activation of GLUR.
authors.affiliation: Laboratorio Biofisica, Centro Ricerca Sperimentale IRE, Roma, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Ragozzino
authors.forename: F
authors.initials: F
authors.lastname: Eusebi
mesh_terms: D000818:Animals; D058787:GABA-A Receptor Antagonists; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects*; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D018009:Receptors, Glycine / Q000037:antagonists & inhibitors*; D013569:Synapses / Q000187:drug effects
chemical_list: D058787:GABA-A Receptor Antagonists; D005971:Glutamates; D018377:Neurotransmitter Agents; D018009:Receptors, Glycine; D018698:Glutamic Acid; D011493:Protein Kinase C