Youngentob S L, Kent P F, Margolis F L
Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA.
J Neurophysiol. 2003 Dec;90(6):3864-73. doi: 10.1152/jn.00806.2002. Epub 2003 Aug 13.
Previous behavioral work, using a complex five-odorant identification task, demonstrated that olfactory marker protein (OMP) is critically involved in odor processing to the extent that its loss results in an alteration in odorant quality perception. Exactly how the lack of OMP exerts its influence on the perception of odorant quality is unknown. However, there is considerable neurophysiological evidence that different odorants produce different spatiotemporal patterns of neural activity at the level of the mucosa and that these patterns predict the psychophysically determined perceptual relationship among odorants. In this respect, OMP gene deletion is known to result in a constellation of physiologic defects (i.e., marked reduction in the electroolfactogram (EOG) and altered response and recovery kinetics) that would be expected to alter the odorant-induced spatiotemporal activity patterns that are characteristic of different odorants. This, in turn, would be expected to alter the spatiotemporal patterning of information that results from the mucosal projection onto the bulb, thereby changing odorant quality perception. To test the hypothesis that odorant-induced mucosal activity patterns are altered in mice lacking the gene for OMP, we optically recorded the fluorescent changes in response to odorant stimulation from both the septum and turbinates of both OMP-null and control mice using a voltage-sensitive dye (di-4-ANEPPS Molecular Probes, Eugene, OR) and a Dalsa 120 x 120, 12-bit CCD camera. To maintain continuity with the previous behavioral work, the odorants 2-propanol, citral, carvone, ethylacetoacetate, and propyl acetate were again used. Each odorant was randomly presented to each mucosal surface in a Latin-Square design. The results of this study demonstrated that, for both mouse strains, there do indeed exist different spatiotemporal activity patterns for different odorants. More importantly, however, these patterns significantly differed between OMP-null and control mice. That is, although the general regions of characteristic activity for different odorants were the same in both mouse strains, the patterns in the null animals were degraded relative to controls. These data suggest therefore that the alterations in mucosal activity may serve as the substrate for the behaviorally observed changes in odorant quality perception in the null mutant.
以往的行为学研究，采用复杂的五种气味识别任务，表明嗅觉标记蛋白（OMP）在气味处理过程中起着关键作用，其缺失会导致气味质量感知的改变。OMP的缺乏究竟如何对气味质量感知产生影响尚不清楚。然而，有大量神经生理学证据表明，不同的气味剂在黏膜水平上会产生不同的神经活动时空模式，并且这些模式预测了气味剂之间心理物理学确定的感知关系。在这方面，已知OMP基因缺失会导致一系列生理缺陷（即嗅电图（EOG）显著降低以及反应和恢复动力学改变），这些缺陷预计会改变不同气味剂特有的气味剂诱导的时空活动模式。反过来，这预计会改变从黏膜投射到嗅球所产生的信息的时空模式，从而改变气味质量感知。为了检验在缺乏OMP基因的小鼠中气味剂诱导的黏膜活动模式发生改变这一假设，我们使用电压敏感染料（di-4-ANEPPS，Molecular Probes，俄勒冈州尤金市）和Dalsa 120×120、12位CCD相机，对OMP基因敲除小鼠和对照小鼠的鼻中隔和鼻甲对气味剂刺激的荧光变化进行了光学记录。为了与之前的行为学研究保持连续性，再次使用了2-丙醇、柠檬醛、香芹酮、乙酰乙酸乙酯和乙酸丙酯这几种气味剂。每种气味剂以拉丁方设计随机呈现给每个黏膜表面。这项研究的结果表明，对于两种小鼠品系，不同气味剂确实存在不同的时空活动模式。然而，更重要的是，这些模式在OMP基因敲除小鼠和对照小鼠之间存在显著差异。也就是说，尽管两种小鼠品系中不同气味剂的特征活动的大致区域相同，但基因敲除动物中的模式相对于对照有所退化。因此，这些数据表明黏膜活动的改变可能是基因敲除突变体中行为学观察到的气味质量感知变化的基础。
