title: Osmotic tension as a possible link between GABA(A) receptor activation and intracellular calcium elevation.
abstract: Intracellular calcium concentration rises have been reported following activation of GABA(A) receptors in neonatal preparations and attributed to activation of voltage-dependent Ca(2+) channels. However, we show that, in cerebellar interneurons, GABA(A) agonists induce a somatodendritic Ca(2+) rise that persists at least until postnatal day 20 and is not mediated by depolarization-induced Ca(2+) entry. A local Ca(2+) elevation can likewise be elicited by repetitive stimulation of presynaptic GABAergic afferent fibers. We find that, following GABA(A) receptor activation, bicarbonate-induced Cl(-) entry leads to cell depolarization, Cl(-) accumulation, and osmotic tension. We propose that this tension induces the intracellular Ca(2+) rise as part of a regulatory volume decrease reaction. This mechanism introduces an unexpected link between activation of GABA(A) receptors and intracellular Ca(2+) elevation, which could contribute to activity-driven synaptic plasticity.
authors.affiliation: Laboratoire de Physiologie Cérébrale, CNRS UMR 8118, Université Paris 5, 45 rue des Saints Pères, 75006 Paris, France.
authors.forename: Joël
authors.initials: J
authors.lastname: Chavas
authors.forename: Maria Elisa
authors.initials: ME
authors.lastname: Forero
authors.forename: Thibault
authors.initials: T
authors.lastname: Collin
authors.forename: Isabel
authors.initials: I
authors.lastname: Llano
authors.forename: Alain
authors.initials: A
authors.lastname: Marty
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D002531:Cerebellum / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology; D007395:Interneurons / Q000502:physiology*; D007424:Intracellular Fluid / Q000737:chemistry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009118:Muscimol / Q000494:pharmacology; D009473:Neuronal Plasticity / Q000502:physiology; D009924:Organ Culture Techniques; D009995:Osmosis / Q000502:physiology*; D051381:Rats; D011963:Receptors, GABA-A / Q000502:physiology*
chemical_list: D018755:GABA Agonists; D011963:Receptors, GABA-A; D009118:Muscimol; D002118:Calcium