Excitatory actions of gaba during development: the nature of the nurture.
In the immature brain, GABA (gamma-aminobutyric acid) is excitatory, and GABA-releasing synapses are formed before glutamatergic contacts in a wide range of species and structures. GABA becomes inhibitory by the delayed expression of a chloride exporter, leading to a negative shift in the reversal potential for choride ions. I propose that this mechanism provides a solution to the problem of how to excite developing neurons to promote growth and synapse formation while avoiding the potentially toxic effects of a mismatch between GABA-mediated inhibition and glutamatergic excitation. As key elements of this cascade are activity dependent, the formation of inhibition adds an element of nurture to the construction of cortical networks.
Ben-Ari
Yehezkel
Y
Institut de Neurobiologie de la Méditerranée (INMED), INSERM Unit 29, Parc Scientifique de Luminy, 13273 Marseille Cedex 09, France. ben-ari@inmed.univ-mrs.fr
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D018118:Chloride Channels / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D006801:Humans; D009415:Nerve Net / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D018079:Receptors, GABA / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018118:Chloride Channels; D018079:Receptors, GABA; D017470:Receptors, Glutamate; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid