Suzuki Noriyo, Takahata Masakazu, Shoji Takayuki, Suzuki Yuko
Animal Behavior and Intelligence, Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
Chem Senses. 2004 Jun;29(5):411-24. doi: 10.1093/chemse/bjh042.
Electro-olfactogram (EOG) oscillations induced by odorant stimulation have been often reported in various vertebrates from fishes to mammals. However, the mechanism of generation of EOG oscillations remains unclear. In the present study, we first characterized the properties of EOG oscillations induced by amino acid odorants in the rainbow trout and then performed a computer simulation based on the main assumption that olfactory receptor neurons (ORNs) have intrinsic oscillatory properties due to two types of voltage-gated ion channels, which have not yet been reported in vertebrate ORNs. EOG oscillations appeared mostly on the peak and decay phases of negative EOG responses, when odorant stimuli at high intensity flowed regularly anterior to posterior olfactory lamellae in the olfactory organ. The appearance of EOG oscillations was dependent on the odorant intensity but not on the flow rate. The maximum amplitude and the maximum power frequency of EOG oscillations were 3.51 +/- 3.35 mV (mean +/- SD, n = 232, range 0.12-16.79 mV) and 10.59 +/- 5.05 Hz (mean +/- SD, n = 232, range 3.51-40.03 Hz), respectively. The simulation represented sufficiently well the characteristics of EOG oscillations; occurrence at high odorant concentration, odorant concentration-dependent amplitude and the maximum power frequency range actually observed. Our results suggest that EOG oscillations are due to the intrinsic oscillatory properties of individual ORNs, which have two novel types of voltage-gated ion channels (resonant and amplifying channels). The simulation program for Macintosh ('oscillation 3.2.4' for MacOS 8.6 or later) is available on the world wide web (http://bio2.sci.hokudai.ac.jp/bio/chinou1/noriyo_home.html).
从鱼类到哺乳动物的各种脊椎动物中，经常有关于气味刺激诱发的电嗅图（EOG）振荡的报道。然而，EOG振荡的产生机制仍不清楚。在本研究中，我们首先对虹鳟鱼中氨基酸气味剂诱发的EOG振荡特性进行了表征，然后基于嗅觉受体神经元（ORN）由于两种尚未在脊椎动物ORN中报道的电压门控离子通道而具有内在振荡特性这一主要假设进行了计算机模拟。当高强度的气味刺激在嗅觉器官中从前向后嗅板有规律地流动时，EOG振荡大多出现在负EOG反应的峰值和衰减阶段。EOG振荡的出现取决于气味剂强度而非流速。EOG振荡的最大振幅和最大功率频率分别为3.51±3.35 mV（平均值±标准差，n = 232，范围0.12 - 16.79 mV）和10.59±5.05 Hz（平均值±标准差，n = 232，范围3.51 - 40.03 Hz）。该模拟充分体现了EOG振荡的特征；在高气味剂浓度下出现、与气味剂浓度相关的振幅以及实际观察到的最大功率频率范围。我们的结果表明，EOG振荡是由于单个ORN的内在振荡特性所致，这些ORN具有两种新型的电压门控离子通道（共振通道和放大通道）。适用于Macintosh的模拟程序（适用于MacOS 8.6或更高版本的“oscillation 3.2.4”）可在万维网（http://bio2.sci.hokudai.ac.jp/bio/chinou1/noriyo_home.html）上获取。
