Psychology Department, Behavioral and Systems Neuroscience Section, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America.
PLoS One. 2013 Apr 22;8(4):e61431. doi: 10.1371/journal.pone.0061431. Print 2013.
Olfactory marker protein (OMP) is highly and selectively expressed in primary olfactory sensory neurons (OSNs) across species, but its physiological function remains unclear. Previous studies in the olfactory epithelium suggest that it accelerates the neural response to odorants and may modulate the odorant-selectivity of OSNs. Here we used a line of gene-targeted mice that express the fluorescent exocytosis indicator synaptopHluorin in place of OMP to compare spatiotemporal patterns of odorant-evoked neurotransmitter release from OSNs in adult mice that were heterozygous for OMP or OMP-null. We found that these patterns, which constitute the primary neural representation of each odorant, developed more slowly during the odorant presentation in OMP knockout mice but eventually reached the same magnitude as in heterozygous mice. In the olfactory bulb, each glomerulus receives synaptic input from a subpopulation of OSNs that all express the same odor receptor and thus typically respond to a specific subset of odorants. We observed that in OMP knockout mice, OSNs innervating a given glomerulus typically responded to a broader range of odorants than in OMP heterozygous mice and thus each odorant evoked synaptic input to a larger number of glomeruli. In an olfactory habituation task, OMP knockout mice behaved differently than wild-type mice, exhibiting a delay in their onset to investigate an odor stimulus during its first presentation and less habituation to that stimulus over repeated presentations. These results suggest that the actions of OMP in olfactory transduction carry through to the primary sensory representations of olfactory stimuli in adult mice in vivo.
嗅觉标记蛋白（OMP）在不同物种的初级嗅觉感觉神经元（OSN）中高度且特异性表达，但它的生理功能仍不清楚。嗅觉上皮中的先前研究表明，它加速了对气味的神经反应，并可能调节 OSN 对气味的选择性。在这里，我们使用了一种表达荧光胞吐指示剂 synaptopHluorin 代替 OMP 的基因靶向小鼠系，以比较杂合子或 OMP 缺失的成年小鼠中 OSN 对气味刺激的神经递质释放的时空模式。我们发现，这些模式构成了每种气味的主要神经表示，在 OMP 敲除小鼠中，在气味呈现期间的发展速度较慢，但最终达到与杂合子小鼠相同的幅度。在嗅球中，每个神经球接收来自表达相同气味受体的 OSN 亚群的突触输入，因此通常对特定的气味子集有反应。我们观察到，在 OMP 敲除小鼠中，支配特定神经球的 OSN 通常对更广泛范围的气味有反应，而不是在 OMP 杂合子小鼠中，因此每种气味都引起更多数量的神经球的突触输入。在嗅觉习惯化任务中，OMP 敲除小鼠的行为与野生型小鼠不同，在首次呈现气味刺激时，它们开始调查该刺激的时间延迟，并且对该刺激的习惯化程度降低。这些结果表明，OMP 在嗅觉转导中的作用在体内成年小鼠的嗅觉刺激的主要感觉表示中得以延续。
