Mechanisms of induction and expression of long-term depression at GABAergic synapses in the neonatal rat hippocampus.
Synaptic plasticity at excitatory glutamatergic synapses is believed to be instrumental in the maturation of neuronal networks. Using whole-cell patch-clamp recordings, we have studied the mechanisms of induction and expression of long-term depression at excitatory GABAergic synapses in the neonatal rat hippocampus (LTD(GABA-A)). We report that the induction of LTD(GABA-A) requires a GABA(A) receptor-mediated membrane depolarization, which is necessary to remove the Mg(2+) block from postsynaptic NMDA receptors. LTD(GABA-A) is associated with an increase in the coefficient of variation of evoked GABA(A) receptor-mediated synaptic currents and a decrease in the frequency, but not amplitude, of Sr(2+)-induced asynchronous GABA(A) quantal events. We conclude that LTD(GABA-A) induction requires the activation of both GABA(A) and NMDA postsynaptic receptors and that its expression is likely presynaptic.
Caillard
O
O
Institut de Neurobiologie de la Mediterranée (INMED), Institut National de la Santé et de la Recherche Médicale U29, B.P. 13, 13273 Marseille Cedex 09, France.
Ben-Ari
Y
Y
Gaïarsa
J L
JL
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D011789:Quantum Theory; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013324:Strontium / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D011963:Receptors, GABA-A; D016194:Receptors, N-Methyl-D-Aspartate; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate; D002118:Calcium; D001640:Bicuculline; D013324:Strontium