Calcium-activated chloride current amplifies the response to urine in mouse vomeronasal sensory neurons.
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.
Yang
Chun
C
Department of Biology, University of Vermont, Burlington, VT 05405, USA.
Delay
Rona J
RJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology*; D014556:Urine; D019147:Vomeronasal Organ / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D018118:Chloride Channels; D002118:Calcium