Silva Vivian Alessandra, Gomide Vânia Canterucci, Chadi Gerson
Laboratory of Neuroregeneration, Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
J Morphol. 2005 Aug;265(2):141-51. doi: 10.1002/jmor.10345.
Recent findings have pointed out the role of neurotrophic factors in the survival and maintenance of neurons of the auditory system. Basic fibroblast growth factor (bFGF, FGF-2) is a potent neurotrophic molecule whose actions can be seen in the central and peripheral nervous systems. In the present study, FGF-2 immunoreactivity was analyzed in the auditory pathways of the adult rat, employing a well-characterized polyclonal antibody against FGF-2. In the cochlea, FGF-2 immunoreactivity was observed in the inner and outer hair cells of the organ of Corti, spiral ganglion neurons, spiral limbus, and stria vascularis. Stereological methods employing optical fractionator revealed the presence of 84.5, 15, and 0.5% of spiral ganglion neurons possessing FGF-2 immunoreactivity of strong, moderate, and weak intensity, respectively. In the central auditory pathways, FGF-2 immunoreactivity was found in the cytoplasm of the neurons of the cochlear nuclei, trapezoid body nuclei, medial geniculate nucleus, and inferior colliculus. The two-color immunoperoxidase method showed FGF-2 immunoreactivity in the nuclei of astrocytes throughout the central auditory pathway. Computer-assisted microdensitometric image analysis revealed higher levels of specific mean gray values of FGF-2 immunoreactivity in the trapezoid body and ventral cochlear nucleus and also in the spiral ganglion and inner hair cells. Sections incubated with FGF-2 antibody preabsorbed with human recombinant FGF-2 showed no immunoreaction in the majority of the studied regions, exhibiting only a slight immunoreactive product in the hair cells of the organ of Corti. Furthermore, no changes in immunoreactivity were observed in sections incubated with FGF-2 antiserum preincubated with human recombinant acidic FGF (FGF-1). The findings suggest that FGF-2 may exert paracrine and autocrine actions on neurons of the central and peripheral auditory systems and may be of importance in the mechanism of hearing diseases.
最近的研究结果指出了神经营养因子在听觉系统神经元存活和维持中的作用。碱性成纤维细胞生长因子（bFGF，FGF-2）是一种有效的神经营养分子，其作用可见于中枢和外周神经系统。在本研究中，使用一种针对FGF-2的特性明确的多克隆抗体，对成年大鼠听觉通路中的FGF-2免疫反应性进行了分析。在耳蜗中，在柯蒂氏器的内、外毛细胞、螺旋神经节神经元、螺旋缘和血管纹中观察到FGF-2免疫反应性。采用光学分选器的体视学方法显示，分别有84.5%、15%和0.5%的螺旋神经节神经元具有强、中、弱强度的FGF-2免疫反应性。在中枢听觉通路中，在耳蜗核、斜方体核、内侧膝状体核和下丘的神经元细胞质中发现了FGF-2免疫反应性。双色免疫过氧化物酶法显示，在整个中枢听觉通路的星形胶质细胞核中存在FGF-2免疫反应性。计算机辅助显微密度图像分析显示，在斜方体和蜗腹侧核以及螺旋神经节和内毛细胞中，FGF-2免疫反应性的特定平均灰度值较高。用人重组FGF-2预吸收的FGF-2抗体孵育的切片在大多数研究区域未显示免疫反应，仅在柯蒂氏器的毛细胞中显示出轻微的免疫反应产物。此外，用人重组酸性FGF（FGF-1）预孵育的FGF-2抗血清孵育的切片中未观察到免疫反应性变化。这些发现表明，FGF-2可能对中枢和外周听觉系统的神经元发挥旁分泌和自分泌作用，并且可能在听力疾病的机制中具有重要意义。
