Giovannelli L, Casamenti F, Pepeu G
Department of Preclinical and Clinical Pharmacology, University of Florence, Italy.
J Neural Transm (Vienna). 1998;105(8-9):935-48. doi: 10.1007/s007020050103.
A unilateral quisqualic acid lesion was placed in the nucleus basalis magnocellularis of 3- and 24-month-old rats, and the animals were sacrificed at different times post-surgery. The morphology and the number of the cholinergic neurons of the nucleus basalis were analyzed by means of immunohistochemistry for cholineacetyltransferase, in order to evaluate the size and severity of the lesion. Immunohistochemistry for the immediate early gene c-fos was also performed in order to clarify its role in the process of neurodegeneration following the excitotoxin injection. The DNA laddering and TUNEL techniques were used to define the type of cell death involved. At short times (4 hr) the lesion induced alterations in the morphology of cholinergic neurons of the nucleus basalis. Subsequently, a significant decrease in the number of neurons was found in comparison to the contralateral unlesioned side. In the older animals the loss of cholineacetyltransferase immunoreactivity had an earlier onset (4 hr) than in the young (24 hr). C-fos expression was induced by the lesion and not by saline injection in the nucleus basalis and in neighbouring areas of the brain as early as 4 hr after surgery. The c-fos protein was no longer present by 24 hr. Furthermore, the c-fos gene product was consistently absent from the nuclei of cholinergic cells. The aged animals exhibited a slower and smaller increase in c-fos as measured by counting the labelled nuclei in the injected area. Analysis of DNA fragmentation did not provide any evidence for apoptosis as the type of cell death involved in the cholinergic degeneration. These results indicate that the c-fos protein might have a protective role in the response to excitotoxic lesions. Furthermore, we have shown that the aged brain displays a reduced ability to produce a c-fos-mediated plastic response to the lesion.
在3个月和24个月大的大鼠基底核大细胞部进行单侧喹啉酸损伤，并在手术后不同时间处死动物。通过对胆碱乙酰转移酶进行免疫组织化学分析基底核胆碱能神经元的形态和数量，以评估损伤的大小和严重程度。还进行了即时早期基因c-fos的免疫组织化学分析，以阐明其在兴奋性毒素注射后神经退行性变过程中的作用。使用DNA梯状条带和TUNEL技术来确定所涉及的细胞死亡类型。在短时间（4小时）时，损伤导致基底核胆碱能神经元形态改变。随后，与对侧未损伤侧相比，发现神经元数量显著减少。在老年动物中，胆碱乙酰转移酶免疫反应性的丧失比年轻动物（24小时）更早出现（4小时）。损伤最早在手术后4小时就诱导了基底核和脑邻近区域的c-fos表达，而生理盐水注射则未诱导。c-fos蛋白在24小时时不再存在。此外，胆碱能细胞的细胞核中始终不存在c-fos基因产物。通过计数注射区域标记的细胞核来测量，老年动物的c-fos增加较慢且较小。DNA片段化分析未提供任何证据表明凋亡是胆碱能变性所涉及的细胞死亡类型。这些结果表明，c-fos蛋白可能在对兴奋性毒性损伤的反应中起保护作用。此外，我们已经表明，老年大脑对损伤产生c-fos介导的可塑性反应的能力降低。
