猫外膝体中脑源性神经营养因子及其受体表达的年龄相关性变化

Age-Related Changes in the Expression of Brain-Derived Neurotrophic Factor and Its Receptors in the Cat Lateral Geniculate Nucleus

【目的】探讨猫外膝体(LGN)中脑源性神经营养因子(BDNF)及受体TrkB和P75NTR的年龄差异性表达及视觉功能老年衰退的神经机制。【方法】制作外膝体冠状连续切片,免疫组织化学染色法显示猫外膝体各层BDNF及TrkB、P75NTR表达差异。Olympus光镜观察切片、采集图像,Image-Pro Express 6.0软件分析计算免疫阳性细胞密度及阳性反应平均光吸收值,SPSS13.0软件数据分析。【结果】青年组及老年组猫外膝体BDNF及TrkB、P75NTR各层均有表达;老年组猫外膝体各层中BDNF及TrkB、P75NTR阳性细胞密度及阳性反应强度较青年组一致下降(P<0.01),且BDNF及TrkB、P75NTR表达存在显著相关性(P<0.01)。【结论】猫外膝体中BDNF及TrkB、P75NTR表达存在年龄性差异,且年龄性表达下降可能是视觉功能老年化衰退原因之一。

【Objective】To investigate possible age-related differences and the neural mechanism that may have an impact on the visual function of old individuals by examing the expression of brain-derived neurotrophic factor(BDNF) and its receptor-tyrosine kinase B(TrkB) as well as P75 NTR in the cat lateral geniculate nucleus(LGN).【Method】The expression of BDNF,TrkB and P75 NTR in each layer of cat lateral geniculate was labeled by immunohistochemistry technique,and was observed and photographed under Olympus microscope. Immunoreactive cells were counted and immunohistochemical positive optical density was measured. Statistical counting and measuring were completed with the software of Image-Pro Express 6.0,and data analysis was carried out by using SPSS 13.0.【Result】BDNF、TrkB and P75 NTR were all expressed in the cat lateral geniculate nucleus in the young group and the old group. Compared with the young group,a significant and consistent decline of the density of immunoreactive cells and intensity of immunohistochemical positive reaction was detected in each layer of cat lateral geniculate nucleus in elderly group(P<0.01). There was a significant correlation among the expression of BDNF,TrkB and P75 NTR(P<0.01).【Conclusion】The age-related reduction of BDNF,TrkB and P75 NTR expression occur in the cat lateral geniculate nucleus. This suggests that the age-related change could be one of the reasons that mediate the decline of visual function in the aged individuals.