Impaired GABAergic transmission disrupts normal homeostatic plasticity in rat cortical networks.
In the cortex, homeostatic plasticity appears to be a key process for maintaining neuronal network activity in a functional range. This phenomenon depends on close interactions between excitatory and inhibitory circuits. We previously showed that application of a high frequency of stimulation (HFS) protocol in layer 2/3 induces parallel potentiation of excitatory and inhibitory inputs on layer 5 pyramidal neurons, leading to an unchanged excitation/inhibition (E/I) balance. These coordinated long-term potentiations of excitation and inhibition correspond to homeostatic plasticity of the neuronal networks. We showed here, on the rat visual cortex, that blockade (with gabazine) or overactivation (with 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) of GABA(A) receptors enhanced the E/I balance and prevented the potentiation of excitatory and inhibitory inputs after an HFS protocol. These impairements of the GABAergic transmission led to a long-term depression-like effect after an HFS protocol. We also observed that the blockade of inhibition reduced excitation (by 60%), and conversely, the blockade of excitation decreased inhibition (by 90%). These results support the idea that inhibitory interneurons are critical for recurrent interactions underlying homeostatic plasticity in cortical networks.
Le Roux
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CNRS, Institut de Neurobiologie Alfred Fessard-FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire-UPR9040, Gif sur Yvette F-91198, France. leroux@nbcm.cnrs-gif.fr
Amar
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M
Moreau
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A
Baux
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G
Fossier
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P
D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D006706:Homeostasis / Q000502:physiology; D007555:Isoxazoles / Q000494:pharmacology; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology; D008959:Models, Neurological; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D017966:Pyramidal Cells / Q000502:physiology; D011724:Pyridazines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D018755:GABA Agonists; D018756:GABA Antagonists; D007555:Isoxazoles; D011724:Pyridazines; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C049853:gabazine; C015542:gaboxadol