Kalesnykas G, Tuulos T, Uusitalo H, Jolkkonen J
Department of Ophthalmology, Institute of Clinical Medicine, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland.
Neuroscience. 2008 Aug 26;155(3):937-47. doi: 10.1016/j.neuroscience.2008.06.038. Epub 2008 Jun 21.
Experimental cerebral ischemia induces a stress response in neuronal and non-neuronal cells. In the present study we aimed to evaluate detailed cellular stress responses and neurodegenerative changes in the retinas in rat focal cerebral ischemia and hypoperfusion models involving invasive vascular manipulations. Independent groups of adult male Wistar rats were subjected to i) transient middle cerebral artery occlusion (tMCAO), ii) permanent middle cerebral artery occlusion (pMCAO), iii) cortical photothrombosis of the sensorimotor cortex using Rose Bengal dye or iv) bilateral common carotid artery occlusion (BCCAO). Rats were killed, and their eyes with the optic nerves enucleated and processed for histology, immunohistochemistry for neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), hypoxia-inducible factor 1alpha (HIF-1alpha), c-fos, alphaB-crystallin, heat shock protein (HSP) 27, HSP60 and HSP70, and detection of DNA defragmentation. The total number of the retinal ganglion cell layer (RGCL) neurons and GFAP-immunoreactive astrocytes located in the nerve fiber layer were estimated using unbiased stereological counting. Our findings indicate that although permanent and transient MCAO does not cause detectable morphological alterations in the retina or optic nerve, it evokes ischemic stress as revealed by HIF-1alpha and HSPs expression in the RGCL neurons and reactive gliosis in the Müller cells. Severe neurodegenerative changes in the retina and optic nerve of the BCCAO rats are accompanied by a significant increase in immunoreactivities for the c-fos, HSP27 and HSP70 as compared with the sham-operated animals. The retinas from the ipsilateral side of the Rose Bengal model showed a significant decrease in the total number of NeuN-positive neurons in the RGCL as compared with the contralateral ones. However, these eyes did not differ between each other in the HSPs and HIF-1alpha expression or in the GFAP-immunoreactivity of the Müller cells. In conclusion, our data suggest differential expression of various HSPs in the retina and possibly their distinct roles in the cerebral ischemia-mediated stress response and neurodegeneration.
实验性脑缺血可在神经元和非神经元细胞中引发应激反应。在本研究中，我们旨在评估大鼠局灶性脑缺血和低灌注模型（涉及侵入性血管操作）视网膜中详细的细胞应激反应和神经退行性变化。将成年雄性Wistar大鼠独立分组，分别进行以下操作：i）短暂性大脑中动脉闭塞（tMCAO）；ii）永久性大脑中动脉闭塞（pMCAO）；iii）使用孟加拉玫瑰红染料对感觉运动皮层进行皮质光血栓形成；iv）双侧颈总动脉闭塞（BCCAO）。处死大鼠，摘除其带有视神经的眼睛并进行组织学处理、针对神经元细胞核（NeuN）、胶质纤维酸性蛋白（GFAP）、缺氧诱导因子1α（HIF-1α）、c-fos、αB-晶状体蛋白、热休克蛋白（HSP）27、HSP60和HSP70的免疫组织化学检测以及DNA片段化检测。使用无偏立体学计数法估计位于神经纤维层的视网膜神经节细胞层（RGCL）神经元和GFAP免疫反应性星形胶质细胞的总数。我们的研究结果表明，尽管永久性和短暂性MCAO不会在视网膜或视神经中引起可检测到的形态学改变，但如RGCL神经元中HIF-1α和HSPs的表达以及Müller细胞中的反应性胶质增生所示，它会引发缺血应激。与假手术动物相比，BCCAO大鼠视网膜和视神经中的严重神经退行性变化伴随着c-fos、HSP27和HSP70免疫反应性的显著增加。与对侧相比，孟加拉玫瑰红模型同侧的视网膜中RGCL中NeuN阳性神经元的总数显著减少。然而，这些眼睛在HSPs和HIF-1α表达或Müller细胞的GFAP免疫反应性方面彼此没有差异。总之，我们的数据表明视网膜中各种HSPs的差异表达以及它们在脑缺血介导的应激反应和神经退行性变中可能具有的不同作用。
