Yang Chun, Delay Rona J
Department of Biology, University of Vermont, Burlington, VT 05405, USA.
J Gen Physiol. 2010 Jan;135(1):3-13. doi: 10.1085/jgp.200910265.
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.
犁鼻器（VNO）是一种气味检测系统，介导许多对信息素敏感的行为。位于犁鼻器中的犁鼻感觉神经元（VSN）是与气味/信息素相互作用的初始位点。然而，单个VSN如何将化学信号转化为电信号仍未得到解决。在这里，我们表明，Ca2+激活的Cl-电流约占小鼠VSN对尿液反应的80%。使用含有短杆菌肽的穿孔膜片钳记录，这种方法不会破坏细胞内的氯离子，我们发现在存在氯离子通道阻滞剂的情况下，尿液诱导的内向电流（V（保持）=-80 mV）会降低。使用全细胞记录并改变细胞外氯离子以改变反转电位，这一点得到了证实。此外，当细胞外Ca2+和Na+都被去除时，尿液诱导的电流就会消失。使用来自树突尖端的内向外膜片，我们记录了Ca2+激活的Cl-通道活性。通过逆转录-聚合酶链反应在犁鼻器中检测到了几种可能的Ca2+激活的Cl-通道候选物。此外，还检测到一种氯共转运体，即Na+-K+-2Cl-同工型1，并发现它介导了VSN中大部分的氯离子积累。总的来说，我们的数据表明，氯离子在小鼠VSN的信号转导中起着主要的放大作用。这种放大作用会增加对信息素或气味剂的反应性。
