Cízková D, Raceková E, Vanický I
Institute of Neurobiology, Slovak Academy of Sciences, Kosice, Slovak Republic.
Physiol Res. 1997;46(6):487-95.
In the present study we investigated the effect of a two-stage bilateral lesion of the olfactory bulb (OB) in rats on the regeneration ability of peripheral olfactory neurons and their reinnervation capacity in the spared OB. The outgrowth of newly-generated olfactory axons as well as the maturation of their terminal synaptic field was detected by immunohistochemistry of the growth-associated phosphoprotein B-50/GAP-43. In addition, the glial response to the surgery was monitored by an immunohistochemical marker for astrocytes, glial fibrillary acidic protein (GFAP). In neonatal rats (P3-P5), the right OB was removed, then three months later the contralateral side was ablated. Six days after the second operation the animals were transcardially perfused. Their brains were embedded in paraplast, serially sectioned and processed for histological and immunohistochemical observations. After neonatal OB ablation, homogeneous B-50-immunoreactivity (BIR) was found in the forebrain, olfactory axons and ectopic glomeruli localized in the small OB remnant-like structures and in the regenerated neuroepithelium. A strong GFAP response was revealed in the brain cortex as well as in the newly-formed olfactory axons and glomeruli-like structures of the OB remnants. After adult OB ablation strong BIR was observed in olfactory axons, while remaining glomerular structures were only faintly stained. The neuroepithelium revealed signs of massive degenerative processes with a substantial decrease in BIR. The GFAP-positive astrocytes were scattered throughout the entire OB remnant and were prominent in the glomeruli-like structures and adjacent frontal cortex. In the present study, we applied GAP-43 and GFAP immunohistochemistry to characterize the responses of individual olfactory components after two-stage olfactory bulbectomy. Furthermore, this model of OB ablation characterized by two immunohistochemical markers could elucidate certain molecular mechanisms involved in the regeneration and/or plasticity of the olfactory system.
在本研究中，我们调查了大鼠嗅球（OB）双侧两阶段损伤对周围嗅觉神经元再生能力及其在保留的OB中的再支配能力的影响。通过生长相关磷蛋白B-50/GAP-43的免疫组织化学检测新生嗅觉轴突的生长及其终末突触场的成熟情况。此外，通过星形胶质细胞的免疫组织化学标记物胶质纤维酸性蛋白（GFAP）监测手术引起的神经胶质反应。在新生大鼠（P3-P5）中，切除右侧OB，三个月后切除对侧。第二次手术后六天，经心脏灌注动物。将它们的大脑包埋在石蜡中，连续切片并进行组织学和免疫组织化学观察。新生OB切除后，在前脑、嗅觉轴突以及位于小OB残余样结构和再生神经上皮中的异位肾小球中发现了均匀的B-50免疫反应性（BIR）。在大脑皮层以及OB残余物的新形成的嗅觉轴突和肾小球样结构中发现了强烈的GFAP反应。成年OB切除后，在嗅觉轴突中观察到强烈的BIR，而其余的肾小球结构仅轻微染色。神经上皮显示出大量退行性过程的迹象，BIR显著降低。GFAP阳性星形胶质细胞散布在整个OB残余物中，在肾小球样结构和相邻的额叶皮层中尤为突出。在本研究中，我们应用GAP-43和GFAP免疫组织化学来表征两阶段嗅球切除术后各个嗅觉成分的反应。此外，这种以两种免疫组织化学标记物为特征的OB切除模型可以阐明嗅觉系统再生和/或可塑性所涉及的某些分子机制。
