Osmotic tension as a possible link between GABA(A) receptor activation and intracellular calcium elevation.

Joël Chavas (1) , Maria Elisa Forero , Thibault Collin (1) , Isabel Llano (1) , Alain Marty (1)

1 LPC - UMR 8118 - Laboratoire de physiologie cérébrale

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.

Domaines: Neurosciences [q-bio.NC]

Joël Chavas, Maria Elisa Forero, Thibault Collin, Isabel Llano, Alain Marty. Osmotic tension as a possible link between GABA(A) receptor activation and intracellular calcium elevation.. Neuron, 2004, 44 (4), pp.701-13. ⟨10.1016/j.neuron.2004.11.002⟩. ⟨hal-00790789⟩