Mechanisms of induction and expression of long-term depression at GABAergic synapses in the neonatal rat hippocampus.

Olivier Caillard (1) , Yehezkel Ben-Ari (1) , Jean-Luc Gaïarsa (1)

1 Epilepsie et ischémie cérébrale

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.

Domaines: Physiologie [q-bio.TO]

Olivier Caillard, Yehezkel Ben-Ari, Jean-Luc Gaïarsa. Mechanisms of induction and expression of long-term depression at GABAergic synapses in the neonatal rat hippocampus.. Journal of Neuroscience, 1999, 19 (17), pp.7568-77. ⟨inserm-00484950⟩