Deng Xiao-hua, Liu Sheng, Cai Wei-jun, Lei De-liang, Luo Xue-gang
Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha 410078,China.
Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2007 Jun;32(3):401-7.
To investigate the changes of anti-apoptotic protein Bcl-2 expression in neurons and activation of brain astroglial cells, and the relationship between astrocytes and neurons in mice after a single intracerebroventricular (ICV) stereotaxic injection of lipopolysaccharide (LPS).
C57BL/6J mice of different ages were divided into a control group and an experiment group. Immunohistochemistry to Bcl-2 and that to GFAP were conducted to observe the expression of Bcl-2 protein in neurons and GFAP in astrocytes in the brain at different time-points after the LPS injection. The glial cell type expressing Bcl-2 was characterized with immunofluorescence double labeling.
GFAP-immunoreactive cells in the control mice were observed mainly within hippocampal formation, piriform, entorhinal cortex, septum, striatum, amygdaloid nucleus, subcortical white matter, as well as in the main fiber tracts. At 24 h after the LPS treatment there was no obvious difference in GFAP immunoreactivity compared with the controls. Astrocytes were markedly activated in periventricular brain regions such as hippocampus, the hypothalamic parenchyma surrounding the third ventricle, with larger cell body and hypertrophic processes 2 days after the endotoxin treatment. After the LPS injection, Bcl-2 positive cells were distributed widely in the brain, such as in the cortex (primary and secondary motor cortex, somatosensory cortex), hypothalamic parenchyma surrounding the third ventricle, diagonal band, hippocampus, septum and the red nucleus of the midbrain. At these sites, Bcl-2 induction increased significantly 2 days after the ICV LPS injection, with some subregional differences, peaking on 4th day. No immunofluorescent double labeling cells for GFAP and Bcl-2 were observed in the brain of the mice after the LPS administration, but merging GFAP positive astrocytes and Bcl-2 positive neurons were seen. Double staining for Bcl-2 and GFAP also showed that the projections of activated astrocytes were found in the sheath of Bcl-2 positive neurons 4 days after the ICV LPS administration.
LPS can activate astroglial cells and upregulate of Bcl-2 expression in the neurons in the mouse brain, which may participate in the administration of central nervous system to central-immunity stimulated regulation and the protective response to the inflammatory stimulus. The projections of activated astrocytes are found in the sheath of Bcl-2 positive neurons, indicating that there is close relationship between astrocytes and neurons.
研究单次脑室内(ICV)立体定向注射脂多糖(LPS)后小鼠神经元中抗凋亡蛋白Bcl-2表达的变化、脑星形胶质细胞的激活情况以及星形胶质细胞与神经元之间的关系。
将不同年龄的C57BL/6J小鼠分为对照组和实验组。采用免疫组织化学方法检测Bcl-2和胶质纤维酸性蛋白(GFAP),观察LPS注射后不同时间点脑内神经元中Bcl-2蛋白和星形胶质细胞中GFAP的表达情况。通过免疫荧光双标法对表达Bcl-2的胶质细胞类型进行鉴定。
对照组小鼠中GFAP免疫反应阳性细胞主要见于海马结构、梨状区、内嗅皮质、隔区、纹状体、杏仁核、皮质下白质以及主要纤维束。LPS处理后24小时,GFAP免疫反应性与对照组相比无明显差异。内毒素处理2天后,海马、第三脑室周围下丘脑实质等脑室周围脑区的星形胶质细胞明显激活,细胞体增大,突起增粗。LPS注射后,Bcl-2阳性细胞广泛分布于脑内,如皮质(初级和次级运动皮质、躯体感觉皮质)、第三脑室周围下丘脑实质、斜角带、海马、隔区和中脑红核。在这些部位,ICV注射LPS后2天Bcl-2诱导显著增加,存在一些亚区域差异,在第4天达到峰值。LPS给药后小鼠脑内未观察到GFAP和Bcl-2免疫荧光双标细胞,但可见GFAP阳性星形胶质细胞与Bcl-2阳性神经元融合。Bcl-2和GFAP双重染色还显示,ICV注射LPS后4天,活化星形胶质细胞的突起见于Bcl-2阳性神经元的鞘内。
LPS可激活小鼠脑内星形胶质细胞并上调神经元中Bcl-2的表达,这可能参与中枢神经系统对中枢免疫刺激调节的管理以及对炎症刺激的保护反应。活化星形胶质细胞的突起见于Bcl-2阳性神经元的鞘内,表明星形胶质细胞与神经元之间存在密切关系。