Dual personality of GABA/glycine-mediated depolarizations in immature spinal cord

• DOI: 10.1073/pnas.0704832104
• Publication Date: 2007-06-26T01:05:26Z
• Authors: Céline Jean-Xavier; George Z. Mentis; Michael J. O'Donovan; Daniel Cattaert; Laurent Vinay
• Keywords: 0301 basic medicine; MESH: Rats; Glycine; MESH: gamma-Aminobutyric Acid; MESH: Animals, Newborn; MESH: Glycine; Membrane Potentials; Rats; MESH: Spinal Cord; Mice; 03 medical and health sciences; Animals, Newborn; Inhibitory Postsynaptic Potentials; Spinal Cord; MESH: Membrane Potentials; Animals; MESH: Animals; [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]; [SDV.NEU] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]; MESH: Mice; MESH: Inhibitory Postsynaptic Potentials; gamma-Aminobutyric Acid

The inhibitory action of glycine and GABA in adult neurons consists both shunting incoming excitations moving the membrane potential away from (AP) threshold. By contrast, immature neurons, postsynaptic potentials (IPSPs) are depolarizing; it is generally accepted that, despite their depolarizing action, these IPSPs because Cl(-) conductance increase. Here we investigated integration (dIPSPs) with excitatory inputs neonatal rodent spinal cord by means intracellular recordings lumbar motoneurons a simulation using compartment model program "Neuron." We show that ability to suppress suprathreshold events depends on E(Cl) location synapses. depolarization outlasts changes spreads electrotonically somatodendritic tree, whereas effect restricted local. As consequence, dIPSPs facilitated AP generation subthreshold late phase response. window facilitation became wider as was more depolarized started earlier synapses were moved input. GAD65/67 immunohistochemistry demonstrated existence distal cord. This study demonstrates small can either inhibit or facilitate depending timing location. Our results raise possibility exert facilitatory distant slight may have important consequences for network processing.