Neurotrophin and Trk neurotrophin receptors in the inner ear of Salmo salar and Salmo trutta
Neurotrophin and Trk neurotrophin receptors in the inner ear of Salmo salar and Salmo trutta
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DOI：
10.1111/j.1469-7580.2006.00673.x
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发表时间：
2007-01-01
影响因子：
2.4
通讯作者：
Vega, J. A.
中科院分区：
文献类型：
--
作者：
Catania, S.;Germana, A.;Vega, J. A.
神经营养素 (NT) 及其信号转导 Trk 受体在高等脊椎动物神经系统中特定神经元群的发育和维持中发挥着关键作用。它们负责内耳耳蜗和前庭感觉上皮的神经支配。神经营养素和 Trk 也存在于硬骨鱼中，但它们在内耳中的分布尚不清楚。因此，在本研究中，我们使用蛋白质印迹分析和免疫组织化学研究了 Salmo salar 和 Salmo trutta 的 alevins 内耳中 NT 和 Trk 受体的表达和细胞定位。蛋白质印迹分析显示存在脑源性神经营养因子 (BDNF) 和神经营养蛋白-3 (NT-3)，但不存在神经生长因子 (NGF)，以及所有三种 Trk 受体，即 TrkA、TrkB 和 TrkC，其估计分子量与哺乳动物的预期分子量相似。主要在感觉上皮细胞中检测到神经营养素的特异性免疫反应性。特别是，BDNF 免疫反应性存在于椭圆囊和球囊的黄斑中，而 NT-3 免疫反应性存在于壶腹嵴的感觉上皮中。通常，内耳的感觉上皮缺乏 Trks 的免疫反应性，因此排除了自分泌和/或旁分泌的可能机制。相比之下，静声神经节中神经元的重叠亚群表达 TrkA（约 15%）、TrkB（约 65%）和 TrkC（约 45%）。目前的结果表明，与哺乳动物和鸟类一样，硬骨鱼的内耳表达神经营养蛋白-Trk 系统的成分，但它们的作用仍有待阐明。
Neurotrophins (NTs) and their signal transducing Trk receptors play a critical role in the development and maintenance of specific neuronal populations in the nervous system of higher vertebrates. They are responsible for the innervation of the inner ear cochlear and vestibular sensory epithelia. Neurotrophins and Trks are also present in teleosts but their distribution in the inner ear is unknown. Thus, in the present study, we used Western-blot analysis and immunohistochemistry to investigate the expression and cell localization of both NTs and Trk receptors in the inner ear of alevins of Salmo salar and Salmo trutta. Western-blot analysis revealed the occurrence of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), but not nerve growth factor (NGF), as well as all three Trk receptors, i.e. TrkA, TrkB and TrkC, the estimated molecular weights of which were similar to those expected for mammals. Specific immunoreactivity for neurotrophins was detected mainly in the sensory epithelia. In particular, BDNF immunoreactivity was found in the maculae of the utricle and saccule, whereas NT-3 immunoreactivity was present in the sensory epithelium of the cristae ampullaris. As a rule the sensory epithelia of the inner ear lacked immunoreactivity for Trks, thus excluding possible mechanisms of autocrinia and/or paracrinia. By contrast, overlapping subpopulations of neurons in the statoacoustic ganglion expressed TrkA (about 15%), TrkB (about 65%) and TrkC (about 45%). The present results demonstrate that, as in mammals and birds, the inner ear of teleosts expresses the components of the neurotrophin-Trk system, but their roles remain to be elucidated.