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Articles by R. J. Delay
Total Records ( 2 ) for R. J. Delay
  P Zhang , C Yang and R. J. Delay

Located at the anterior portion of the nose, the paired vomeronasal organs (VNO) detect odors and pheromones. In vomeronasal sensory neurons (VSNs) odor responses are mainly mediated by phospholipase C (PLC), stimulation of which elevates diacylglycerol (DAG). DAG activates a transient receptor potential channel (TRPC2) leading to cell depolarization. In this study, we used a natural stimulus, urine, to elicit odor responses in VSNs and found urine responses persisted in TRPC2–/– mice, suggesting the existence of a TRPC2-independent signal transduction pathway. Using perforated patch-clamp recordings on isolated VSNs from wild-type (WT) and TRPC2–/– mice, we found a PLC inhibitor blocked urine responses from all VSNs. Furthermore, urine responses were reduced by blocking DAG lipase, an enzyme that produces arachidonic acid (AA), in WT mice and abolished in TRPC2–/– mice. Consistently, direct stimulation with AA activated an inward current that was independent of TRPC2 channels but required bath Ca2+ and was blocked by Cd2+. With the use of inside-out patches from TRPC2–/– VSNs, we show that AA activated a channel that also required Ca2+. Together, these data from WT and TRPC2–/– mice suggest that both DAG and its metabolite, AA, mediate excitatory odor responses in VSNs, by activating two types of channels, a TRPC2 and a separate Ca2+-permeable channel.

  C Yang and R. J. Delay

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 ~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 (Vhold = –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.

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