Mobley Arie Sitthichai, Michel William C, Lucero Mary T
Department of Physiology, University of Utah, Salt Lake City, Utah 8409-6500, USA.
Anat Rec (Hoboken). 2008 Jul;291(7):763-74. doi: 10.1002/ar.20704.
In the olfactory organ of the squid, Lolliguncula brevis there are five morphological types of olfactory receptor neurons (ORNs). Previous work to characterize odor sensitivity of squid ORNs was performed on only two of the five types in dissociated primary cell cultures. Here, we sought to establish the odorant responsiveness of all five types. We exposed live squid or intact olfactory organs to excitatory odors plus the activity marker, agmatine (AGB), an arginine derivative that enters cells through nonselective cation channels. An antibody against AGB was used to identify odorant-activated neurons. We were able to determine the ORN types of AGB-labeled cells based on their location in the epithelium, morphology and immunolabeling by a set of metabolites: arginine, aspartate, glutamate, glycine, and glutathione. Of 389 neurons identified from metabolite-labeled tissue, 3% were type 1, 32% type 2, 33% type 3, 15% type 4, and 17% type 5. Each ORN type had different odorant specificity with type 3 cells showing the highest percentages of odorant-stimulated AGB labeling. Type 1 cells were rare and none of the identified type 1 cells responded to the tested odorants, which included glutamate, alanine and AGB. Glutamate is a behaviorally attractive odorant and elicited AGB labeling in types 2 and 3. Glutamate-activated AGB labeling was significantly reduced in the presence of the adenylate cyclase inhibitor, SQ22536 (80 microM). These data suggest that the five ORN types differ in their relative abundance and odor responsiveness and that the adenylate cyclase pathway is involved in squid olfactory transduction.
在短尾乌贼（Lolliguncula brevis）的嗅觉器官中，存在五种形态类型的嗅觉受体神经元（ORN）。此前关于乌贼ORN气味敏感性特征的研究仅在解离的原代细胞培养物中的五种类型中的两种上进行。在这里，我们试图确定所有五种类型的气味反应性。我们将活乌贼或完整的嗅觉器官暴露于兴奋性气味剂以及活性标记物胍丁胺（AGB）中，胍丁胺是一种精氨酸衍生物，可通过非选择性阳离子通道进入细胞。使用针对AGB的抗体来识别气味激活的神经元。我们能够根据AGB标记细胞在上皮中的位置、形态以及一组代谢物（精氨酸、天冬氨酸、谷氨酸、甘氨酸和谷胱甘肽）的免疫标记来确定ORN类型。从代谢物标记的组织中鉴定出的389个神经元中，1型占3%，2型占32%，3型占33%，4型占15%，5型占17%。每种ORN类型具有不同的气味特异性，其中3型细胞在气味刺激的AGB标记中所占百分比最高。1型细胞很少见，且鉴定出的1型细胞均未对测试的气味剂（包括谷氨酸、丙氨酸和AGB）产生反应。谷氨酸是一种具有行为吸引力的气味剂，可在2型和3型细胞中引发AGB标记。在腺苷酸环化酶抑制剂SQ22536（80微摩尔）存在的情况下，谷氨酸激活的AGB标记显著减少。这些数据表明，五种ORN类型在相对丰度和气味反应性方面存在差异，并且腺苷酸环化酶途径参与了乌贼的嗅觉转导。
