Calcium-stores mediate adaptation in axon terminals of Olfactory Receptor Neurons in Drosophila. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue BMC Neuroscience Année : 2011

Calcium-stores mediate adaptation in axon terminals of Olfactory Receptor Neurons in Drosophila.

Résumé

ABSTRACT: BACKGROUND: In vertebrates and invertebrates, sensory neurons adapt to variable ambient conditions, such as the duration or repetition of a stimulus, a physiological mechanism considered as a simple form of non-associative learning and neuronal plasticity. Although various signaling pathways, as cAMP, cGMP, and the inositol 1,4,5-triphosphate receptor (InsP3R) play a role in adaptation, their precise mechanisms of action at the cellular level remain incompletely understood. Recently, in Drosophila, we reported that odor-induced Ca2+-response in axon terminals of olfactory receptor neurons (ORNs) is related to odor duration. In particular, a relatively long odor stimulus (such as 5 s) triggers the induction of a second component involving intracellular Ca2+-stores. RESULTS: We used a recently developed in-vivo bioluminescence imaging approach to quantify the odor-induced Ca2+-activity in the axon terminals of ORNs. Using either a genetic approach to target specific RNAs, or a pharmacological approach, we show that the second component, relying on the intracellular Ca2+-stores, is responsible for the adaptation to repetitive stimuli. In the antennal lobes (a region analogous to the vertebrate olfactory bulb) ORNs make synaptic contacts with second-order neurons, the projection neurons (PNs). These synapses are modulated by GABA, through either GABAergic local interneurons (LNs) and/or some GABAergic PNs. Application of GABAergic receptor antagonists, both GABAA or GABAB, abolishes the adaptation, while RNAi targeting the GABABR (a metabotropic receptor) within the ORNs, blocks the Ca2+-store dependent component, and consequently disrupts the adaptation. These results indicate that GABA exerts a feedback control. Finally, at the behavioral level, using an olfactory test, genetically impairing the GABABR or its signaling pathway specifically in the ORNs disrupts olfactory adapted behavior. CONCLUSION: Taken together, our results indicate that a relatively long lasting form of adaptation occurs within the axon terminals of the ORNs in the antennal lobes, which depends on intracellular Ca2+-stores, attributable to a positive feedback through the GABAergic synapses.

Dates et versions

hal-00637233 , version 1 (31-10-2011)

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Meena S Murmu, Jacques Stinnakre, Eleonore Real, Jean-Rene Martin. Calcium-stores mediate adaptation in axon terminals of Olfactory Receptor Neurons in Drosophila.. BMC Neuroscience, 2011, 12 (1), pp.105. ⟨10.1186/1471-2202-12-105⟩. ⟨hal-00637233⟩

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