GABAB receptor- and metabotropic glutamate receptor-dependent cooperative long-term potentiation of rat hippocampal GABAA synaptic transmission.
The Journal of Physiology. 2003-11-01; 553(1): 155-167
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1. J Physiol. 2003 Nov 15;553(Pt 1):155-67. Epub 2003 Sep 8.
GABAB receptor- and metabotropic glutamate receptor-dependent cooperative
long-term potentiation of rat hippocampal GABAA synaptic transmission.
Patenaude C(1), Chapman CA, Bertrand S, Congar P, Lacaille JC.
(1)Centre de Recherche en Sciences Neurologiques et Département de Physiologie,
Université de Montréal, Montréal, Québec, Canada H3C 3J7.
Repetitive stimulation of Schaffer collaterals induces activity-dependent changes
in the strength of polysynaptic inhibitory postsynaptic potentials (IPSPs) in
hippocampal CA1 pyramidal neurons that are dependent on stimulation parameters.
In the present study, we investigated the effects of two stimulation patterns,
theta-burst stimulation (TBS) and 100 Hz tetani, on pharmacologically isolated
monosynaptic GABAergic responses in adult CA1 pyramidal cells. Tetanization with
100 Hz trains transiently depressed both early and late IPSPs, whereas TBS
induced long-term potentiation (LTP) of early IPSPs that lasted at least 30 min.
Mechanisms mediating this TBS-induced potentiation were examined using whole-cell
recordings. The paired-pulse ratio of monosynaptic inhibitory postsynaptic
currents (IPSCs) was not affected during LTP, suggesting that presynaptic changes
in GABA release are not involved in the potentiation. Bath application of the
GABAB receptor antagonist CGP55845 or the group I/II metabotropic glutamate
receptor antagonist E4-CPG inhibited IPSC potentiation. Preventing postsynaptic
G-protein activation or Ca2+ rise by postsynaptic injection of GDP-beta-S or
BAPTA, respectively, abolished LTP, indicating a G-protein- and Ca2+-dependent
induction in this LTP. Finally during paired-recordings, activation of individual
interneurons by intracellular TBS elicited solely short-term increases in average
unitary IPSCs in pyramidal cells. These results indicate that a stimulation
paradigm mimicking the endogenous theta rhythm activates cooperative postsynaptic
mechanisms dependent on GABABR, mGluR, G-proteins and intracellular Ca2+, which
lead to a sustained potentiation of GABAA synaptic transmission in pyramidal
cells. GABAergic synapses may therefore contribute to functional synaptic
plasticity in adult hippocampus.
PMID: 12963794 [Indexed for MEDLINE]