Analysis of the mechanisims of protection of midbrain dopaminergic neurons by the innervation target with the usage of slice culture preparation

本研究旨在通过脑切片培养，揭示中脑黑质多巴胺能神经元功能保护和维持的相关因素。1. 与纹状体切片共培养时，中脑多巴胺能神经元获得了对NMDA和NO供体细胞毒性的抗性。一氧化氮合酶抑制剂可抑制nmda诱导的单个中脑多巴胺能神经元的丢失。在中脑单一培养中，多巴胺能神经元ONOO的产生水平高于中脑-纹状体共培养。此外，与单独培养的中脑组织相比，与纹状体共培养的中脑组织超氧化物歧化酶（SOD）活性水平升高，Cu、Zn-SOD蛋白水平升高。因此，纹状体组织（中脑多巴胺能神经元的神经支配靶点）的相互作用导致中脑内SOD的增加，这可能有助于增加多巴胺能神经元对兴奋毒性的抵抗。2. 长期存在l型电压依赖性Ca^<2+>通道或电压依赖性Na^+通道阻滞剂的中脑片培养可引起多巴胺能神经元数量的显著减少。同时处理导致细胞内环AMP水平升高，这些影响减弱，这表明自发神经元活动和由此产生的Ca^<2+>流入神经元细胞质，通过环AMP产生的机制有助于维持多巴胺能神经元。3. 一系列具有s受体配体特性的化合物通过调节NMDA受体的功能，对多巴胺能神经元抗兴奋性毒性损伤具有显著的保护作用。这些结果揭示了中脑多巴胺能神经元内源性保护系统的几个方面，这可能有助于建立预防和治疗帕金森病的新策略。少

This study was aimed to reveal factors contributing to the protection and the maintenance of functions of nigral dopaminergic neurons in the midbrain, using brain slice culture preparations. 1. Dopaminergic neurons in midbrain slice cultures acquired resistance to the cytotoxicity of NMDA and NO donors, when they were co-cultured with the striatal slices. NMDA-induced loss of dopaminergic neurons in single midbrain cultures was suppressed by an NO synthase inhibitor. The levels of ONOO production in dopaminergic neurons were higher in single midbrain cultures than in midbrain-striatum co-cultures. In addition, midbrain tissues co-cultured with the striatum exhibited an increased level of superoxide dismutase (SOD) activity as well as an increased level of Cu,Zn-SOD proteins, compared to midbrain tissues cultured alone. Therefore, interactions of the striatal tissue, an innervation target of the midbrain dopaminergic neurons, result in an increase in SOD within the midbrain, which may c … More ontribute to the increased resistance of dopaminergic neurons to excitotoxicity. 2. Cultivation of midbrain slices in the chronic presence of blockers of L-type voltage-dependent Ca^<2+> channels or voltage-dependent Na^+ channels was found to cause a dramatic decrease in the number of dopaminergic neurons. These effects were attenuated by concurrent treatments that caused elevation of intracellular levels of cyclic AMP, suggesting that spontaneous neuronal activity and resultant Ca^<2+> influx into neuronal cytoplasm contribute to the maintenance of dopaminergic neurons through the mechanisms involving cyclic AMP production. 3. A series of compounds with properties of s receptor ligands were found to afford remarkable protection of dopaminergic neurons against excitotoxic insults, by modulating the functions of NMDA receptors. These results revealed several aspects of endogenous protective systems for midbrain dopaminergic neurons, which may contribute to the establishment of novel strategies for prevention and treatment of Parkinson's disease. Less