Calcium activated chloride current amplifies the response to urine in mouse vomeronasal sensory neurons.

Publication: The Journal of general physiology
Publication Date: 2010
Study Author(s): Yang, Chun;Delay, Rona J;
Institution: Department of Biology, University of Vermont, Burlington, VT 05405, USA.
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The vomeronasal organ (VNO) is an odor detection system that mediates many pheromone-sensitive behaviors. Vomeronasal sensory neurons (VSNs), located in the VNO, are the initial site of interaction with odors/pheromones. However, how an individual VSN transduces chemical signals into electrical signals is still unresolved. Here, we show that a Ca2+-activated Cl- current contributes approximately 80% of the response to urine in mouse VSNs. Using perforated patch clamp recordings with gramicidin, which leaves intracellular Chloride undisrupted, we found that the urine-induced inward current (V(hold) = -80 mV) was decreased in the presence of chloride channel blockers. This was confirmed using whole cell recordings and altering extracellular chloride to shift the reversal potential. Further, the urine-induced currents were eliminated when both extracellular Ca2+ and Na+ were removed. Using inside-out patches from dendritic tips, we recorded Ca2+-activated Cl- channel activity. Several candidates for this Ca2+-activated Cl- channel were detected in VNO by reverse transcription-polymerase chain reaction. In addition, a chloride cotransporter, Na+-K+-2Cl- isoform 1, was detected and found to mediate much of the chloride accumulation in VSNs. Collectively, our data demonstrate that chloride acts as a major amplifier for signal transduction in mouse VSNs. This amplification would increase the responsiveness to pheromones or odorants.
PMID: 20038523

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