Liman E R, Corey D P
Department of Neurology, Harvard Medical School, Boston, Massachusetts 02114, USA.
J Neurosci. 1996 Aug 1;16(15):4625-37. doi: 10.1523/JNEUROSCI.16-15-04625.1996.
The mechanism of sensory transduction in chemosensory neurons of the vomeronasal organ (VNO) is not known. Based on molecular data, it is likely to be different from that mediating sensory transduction in the main olfactory system. To begin to understand this system, we have characterized the electrophysiological properties of dissociated mouse VNO neurons with patch-clamp recording. Sensory neurons were distinguished from nonsensory neurons by the presence of a dendrite, by immunoreactivity for olfactory marker protein, and by the firing of action potentials. The resting potential of VNO neurons was approximately -60 mV, and the average input resistance was 3 Gomega. Current injections as small as 1-2 pA elicited steady trains of action potentials that showed no sign of elicited steady trains of action potentials that showed no sign of adaptation during a 2 sec stimulus duration. The voltage-gated conductances in VNO neurons are distinct from those in olfactory neurons. The Na+ current is composed of two components; the major component was TTX-sensitive (Ki = 3.6 nM). The outward K+ current activates at -30 mV with kinetics 10 times slower than for K+ currents in olfactory neurons. The Ca2+ current is composed of at least two components: an L-type current and a T-type current that activates at -60 mV and is not found in olfactory neurons. We find no evidence for cyclic nucleotide-gated channels in VNO neurons under a variety of experimental conditions, including those that produced large responses in mouse olfactory neurons, which is further evidence for a novel transduction pathway.
犁鼻器（VNO）化学感受神经元的感觉转导机制尚不清楚。基于分子数据，其可能不同于介导主嗅觉系统感觉转导的机制。为了开始了解这个系统，我们用膜片钳记录法对分离的小鼠VNO神经元的电生理特性进行了表征。感觉神经元通过存在树突、对嗅觉标记蛋白的免疫反应性以及动作电位的发放与非感觉神经元区分开来。VNO神经元的静息电位约为 -60 mV，平均输入电阻为3 GΩ。小至1 - 2 pA的电流注入就能引发稳定的动作电位序列，在2秒的刺激持续时间内没有显示出适应的迹象。VNO神经元中的电压门控电导与嗅觉神经元中的不同。Na⁺电流由两个成分组成；主要成分对TTX敏感（Ki = 3.6 nM）。外向K⁺电流在 -30 mV时激活，其动力学比嗅觉神经元中的K⁺电流慢10倍。Ca²⁺电流至少由两个成分组成：一种L型电流和一种在 -60 mV时激活的T型电流，而这种T型电流在嗅觉神经元中不存在。在各种实验条件下，包括那些在小鼠嗅觉神经元中产生大反应的条件下），我们在VNO神经元中均未发现环核苷酸门控通道的证据，这进一步证明了存在一种新的转导途径。
