Postsynaptically different inhibitory postsynaptic currents in Cajal-Retzius cells in the developing neocortex.
Fast and slowly rising inhibitory postsynaptic currents (IPSCs, IPSCF and IPSCS) in neocortical Cajal-Retzius cells are observed. In this study, zolpidem, a benzodiazepine agonist that specifically modulates gamma-aminobutyric acid type A receptors (GABAARs) containing gamma2 subunit, was used to characterize GABAARs mediating IPSCF and IPSCS. One-hundred-nanomolar zolpidem prolonged IPSCS, increased evoked IPSCS (eIPSCS) amplitude, and decreased paired-pulse ratio (PPR) of eIPSCS. Two micromolar zolpidem prolonged both IPSCF and IPSCS, increased miniature IPSCF and eIPSCF amplitudes, increased eIPSCS amplitude but not miniature IPSCS amplitude, decreased PPR of eIPSCS, but failed to affect PPR of eIPSCF. We conclude that IPSCF are mediated by alpha2/3-containing GABAARs, which are not saturated by synaptic GABA release, whereas IPSCS are mediated by alpha1-containing and alpha2/3-containing GABAARs, which are saturated by quantal GABA release.
Dvorzhak
Anton
A
Institute of Neurophysiology, Johannes-Mueller-Center of Physiology, Charité-University-Medicine Berlin, Berlin, Germany.
Myakhar
Olga
O
Kamkin
Andre
A
Kirmse
Knut
K
Kirischuk
Sergei
S
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects* / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology; D058785:GABA-A Receptor Agonists; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D019579:Neocortex / Q000166:cytology / Q000254:growth & development; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D000077334:Zolpidem
D018755:GABA Agonists; D058785:GABA-A Receptor Agonists; D011725:Pyridines; D011963:Receptors, GABA-A; D000077334:Zolpidem