Activity-Dependent Depression of GABAergic IPSCs in Cultured Hippocampal Neurons
In: Journal of Neurophysiology, Jg. 82 (1999-07-01), Heft 1, S. 42-49
Online
serialPeriodical
Zugriff:
Short-term depression of monosynaptic GABAergic inhibitory postsynaptic currents (IPSCs) evoked between pairs of cultured rat hippocampal neurons was investigated using dual whole cell patch-clamp recordings. Paired stimuli applied to the GABAergic neuron resulted in paired-pulse depression (PPD) of the second IPSC (IPSC2) at interpulse intervals from 25 to 2,000 ms. CGP 55845A, but not CGP 35348, reduced PPD marginally. Brief paired-pulse applications of exogenous GABA indicated that postsynaptic factors made only minimal contribution to PPD of IPSCs. IPSC1and PPD was reduced on lowering [Ca2+]oand enhanced on increasing [Ca2+]o. The potassium-channel blocker 4-aminopyridine (4-AP), which increases presynaptic Ca2+influx, enhanced IPSC1and PPD. Chelation of residual Ca2+in the GABAergic boutons with EGTA-AM enhanced PPD. Stimulation of the presynaptic neuron at frequencies (f) ranging from 2.5 to 80 Hz resulted in tetanic depression of IPSCs, which declined rapidly and reached a plateau depending on fand [Ca2+]o. CGP 55845A decreased tetanic depression in the first part of the train, but this could be overcome with continued stimulation. We show that GABAergic IPSCs are robustly depressed by paired-pulse stimulation in cultured hippocampal neurons. The depression of IPSCs is mainly independent of presynaptic GABABreceptors and could be caused by depletion of releasable vesicles. Depleted synapses recover with a slow time course, depending on factors that regulate [Ca2+]iin the GABAergic boutons.
Titel: |
Activity-Dependent Depression of GABAergic IPSCs in Cultured Hippocampal Neurons
|
---|---|
Autor/in / Beteiligte Person: | Jensen, Kimmo ; Lambert, John D. C. ; Jensen, Morten Skovgaard |
Link: | |
Zeitschrift: | Journal of Neurophysiology, Jg. 82 (1999-07-01), Heft 1, S. 42-49 |
Veröffentlichung: | 1999 |
Medientyp: | serialPeriodical |
ISSN: | 0022-3077 (print) ; 1522-1598 (print) |
DOI: | 10.1152/jn.1999.82.1.42 |
Sonstiges: |
|