Ylikoski J, Pirvola U, Moshnyakov M, Palgi J, Arumäe U, Saarma M
Department of Pathology, University of Helsinki, Finland.
Hear Res. 1993 Feb;65(1-2):69-78. doi: 10.1016/0378-5955(93)90202-c.
In situ hybridization was used to study the expression of mRNAs of nerve growth factor (NGF), brain-derived neutrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-5 (NT-5) and the components of their high-affinity receptors in the early postnatal and adult rat inner ears. NGF or NT-5 transcripts were not detected in the inner ear neuroepithelium or in the innervating neurons. NT-3 mRNA was intensely expressed over the one-week-old and adult inner hair cells (IHCs) but in the outer hair cells (OHCs) and vestibular maculae only during the early postnatal period. BDNF mRNA was expressed in the IHCs and OHCs of the early postnatal cochlea but not in the adult organ of Corti. High levels of BDNF transcripts were observed in the sensory epithelia of all vestibular end organs. mRNAs of low affinity NGF receptor, trkB and trkC, but not of trk, were expressed in the spiral and vestibular ganglia. In addition, the non-catalytic form of trkB mRNA localized to the sensory epithelia of maculae utriculi and sacculi. The present results show that of the neurotrophins examined, NT-3 is the predominant neurotrophin in the adult organ of Corti and BDNF is that in vestibular organs. The expression patterns of NT-3 and BDNF mRNAs suggest that these neurotrophins may participate in the maintenance of mature cochleovestibular neurons and they may be involved in the survival response of injured neurons.
采用原位杂交技术研究出生后早期和成年大鼠内耳中神经生长因子（NGF）、脑源性神经营养因子（BDNF）、神经营养素-3（NT-3）、神经营养素-5（NT-5）及其高亲和力受体各组分mRNA的表达情况。在内耳神经上皮或支配神经元中未检测到NGF或NT-5转录本。NT-3 mRNA在1周龄和成年大鼠的内毛细胞（IHC）中强烈表达，但仅在出生后早期在外毛细胞（OHC）和前庭斑中表达。BDNF mRNA在出生后早期耳蜗的IHC和OHC中表达，但在成年柯蒂器中不表达。在前庭所有终器的感觉上皮中均观察到高水平的BDNF转录本。低亲和力NGF受体、trkB和trkC的mRNA在螺旋神经节和前庭神经节中表达，但trk的mRNA未表达。此外，trkB mRNA的非催化形式定位于椭圆囊斑和球囊斑的感觉上皮。目前的研究结果表明，在所检测的神经营养因子中，NT-3是成年柯蒂器中的主要神经营养因子，BDNF是前庭器官中的主要神经营养因子。NT-3和BDNF mRNA的表达模式表明，这些神经营养因子可能参与成熟耳蜗前庭神经元的维持，并且可能参与受损神经元的存活反应。
