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United States: American Society for Pharmacology and Experimental Therapeutics
Erscheinungsjahr
2006
Quelle
MEDLINE
Beschreibungen/Notizen
The tonic form of GABA-mediated inhibition requires the presence of slowly desensitizing GABA A receptors with high affinity, which has not yet been directly demonstrated in hippocampal neurons. Low concentration of GABA
(1 μM) persistently increased baseline noise, increased membrane slope conductance, but did not affect spontaneous inhibitory
postsynaptic currents (sIPSCs) in dentate granule cells (DGCs). Higher concentrations of GABA (10â100 μM) desensitized synaptic
currents quickly, and there was a large residual current. Saturating concentration of GABA (1 mM) completely desensitized
synaptic currents and revealed a slowly desensitizing, persistent current. Penicillin (300 μM) inhibited baseline noise without
affecting mean current and inhibited decay time of sIPSCs. GABA A receptors mediating baseline noise in DGCs were sensitive to allopregnanolone, furosemide, and loreclezole and insensitive
to diazepam and zolpidem. These studies demonstrate persistently open GABA A receptors on DGCs with high affinity for GABA, slow desensitization rate, and pharmacological properties similar to those
of recombinant receptors containing α 4 , β 1 , and the δ subunits.