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Functional Heterogeneity of Hippocampal GABA A Receptors
Author(s) -
Schönrock Beate,
Bormann Joachim
Publication year - 1993
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1993.tb00957.x
Subject(s) - zolpidem , gabaa receptor , flunitrazepam , hippocampal formation , receptor , chemistry , inhibitory postsynaptic potential , clonazepam , gamma aminobutyric acid , hippocampus , gabab receptor , benzodiazepine , gaba receptor , endocrinology , medicine , pharmacology , neuroscience , biology , biochemistry , insomnia
γ‐Aminobutyric acid type A (GABA A ) receptors were studied in cultured neurons taken from rat hippocampus at early postnatal stages. GABA‐induced whole‐cell currents showed a broad range of peak amplitudes and time‐courses of desensitization. Dose – response curves of rapidly and slowly desensitizing cells revealed EC 50 values of 8.5 and 37.3 μM GABA, respectively, with the Hill coefficient being greater than unity. The main‐state conductance of GABA A receptor channels was 28 – 31 pS in all cells. GABA responses of low‐affinity cells were more strongly affected by benzodiazepine receptor agonists (e.g. flunitrazepam, clonazepam) and inverse agonists (e.g. methyl‐6,7‐dimethoxy‐4‐ethyl‐β‐carboline‐3‐carboxylate), as compared to cells exhibiting high‐affinity GABA responses. Currents were also potentiated by zolpidem, but were little affected by Ro 15‐4513 and Zn 2+ . These data suggest the presence of physiologically and pharmacologically distinct GABA A receptor isoforms in neurons of the early postnatal hippocampus, which may subserve different inhibitory control mechanisms in this brain region.