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Spontaneous synaptic activity is required for the formation of functional GABAergic synapses in the developing rat hippocampus
Author(s) -
ColinLe Brun Isabelle,
Ferrand Nadine,
Caillard Olivier,
Tosetti Patrizia,
BenAri Yehezkel,
Gaïarsa JeanLuc
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.065060
Subject(s) - gabaergic , glutamatergic , tetrodotoxin , neuroscience , ionotropic effect , hippocampal formation , bicuculline , postsynaptic potential , hippocampus , chemistry , gaba transporter , biology , neurotransmission , gabaa receptor , glutamate receptor , biophysics , receptor , inhibitory postsynaptic potential , biochemistry
Here we examine the role of the spontaneous synaptic activity generated by the developing rat hippocampus in the formation of functional γ‐aminobutyric acid (GABA) synapses. Intact hippocampal formations (IHFs) were dissected at birth and incubated for 1 day in control or tetrodotoxin (TTX)‐supplemented medium at 25°C. After the incubation, miniature GABA A ‐mediated postsynaptic currents (mGABA A ‐PSCs) were recorded in whole‐cell voltage‐clamped CA3 pyramidal neurones from IHF‐derived slices. After 1 day in vitro in control medium, the frequency of mGABA A ‐PSCs was similar to that recorded in acute slices obtained 1 day after birth, but significantly higher than the frequency recorded from acute slices just after birth. These results suggest that the factors required in vivo for the formation of functional GABAergic synapses are preserved in the IHFs in vitro . The frequency increase was prevented when IHFs were incubated for 1 day with TTX. TTX treatment affected neither the morphology of CA3 pyramidal neurones nor cell viability. The TTX effects were reproduced when IHFs were incubated in the presence of glutamatergic or GABAergic ionotropic receptor antagonists or in high divalent cationic medium. The present results indicate that the spontaneous synaptic activity generated by the developing hippocampus is a key player in the formation of functional GABAergic synapses, possibly via network events requiring both glutamatergic and GABAergic receptors.