The Styryl Dye FM1-43 Suppresses Odorant Responses in a Subset of Olfactory Neurons by Blocking Cyclic Nucleotide-gated (CNG) Channels

Esther Breunig,Eugen Kludt,Dirk Czesnik,Detlev Schild

doi:10.1074/jbc.m111.233890

Esther Breunig, Eugen Kludt + Show 2 more

Open Access

https://doi.org/10.1074/jbc.m111.233890

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Abstract

Many olfactory receptor neurons use a cAMP-dependent transduction mechanism to transduce odorants into depolarizations. This signaling cascade is characterized by a sequence of two currents: a cation current through cyclic nucleotide-gated channels followed by a chloride current through calcium-activated chloride channels. To date, it is not possible to interfere with these generator channels under physiological conditions with potent and specific blockers. In this study we identified the styryl dye FM1-43 as a potent blocker of native olfactory cyclic nucleotide-gated channels. Furthermore, we characterized this substance to stain olfactory receptor neurons that are endowed with cAMP-dependent transduction. This allows optical differentiation and pharmacological interference with olfactory receptor neurons at the level of the signal transduction.

Highlights

The first step of odorant recognition in vertebrates begins at the level of the olfactory epithelium (OE).2 This consists of three principal cell types: olfactory receptor neurons (ORNs), glia-like sustentacular cells, and basal cells
FM1-43 is presently better known as a means to monitor membrane trafficking (10 –12) and vesicle endocytosis in cochlear hair cells [13, 14], FM1-43 has been reported to stain several sensory and neuronal cells in an endocytosis-independent way, e.g. sensory hair cells in the lateral line organ, cochlea hair cells of various vertebrate species [15,16,17,18], Merkel cells, taste buds, nociceptive fibers, as well as primary sensory neurons in the trigeminal (V), geniculate (VII), petrosal (IX), nodose (X) and dorsal root ganglia (18 –20)
FM1-43 Stains a Subset of ORNs—In a first set of experiments, living X. laevis tadpoles were put into water containing the styryl dye FM1-43 (2 ␮M)

Summary

Introduction

The first step of odorant recognition in vertebrates begins at the level of the olfactory epithelium (OE).2 This consists of three principal cell types: olfactory receptor neurons (ORNs), glia-like sustentacular cells, and basal cells. For imaging [Ca2ϩ]i in ORN somata, tissue slices were incubated in 200 ␮l of a bath solution that contained 50 ␮M Ca2ϩ indicator dye fluo-4 AM (Molecular Probes) and 50 ␮M MK571 (Alexis Biochemicals, Grunberg, Germany).

Results

Conclusion