Laboratório de Neuroproteção e Doenças Metabólicas, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600 anexo, Porto Alegre, RS, 90035-003, Brazil.
Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Neurotox Res. 2018 Jul;34(1):147-163. doi: 10.1007/s12640-017-9834-6. Epub 2017 Nov 9.
The brain of patients affected by Alzheimer's disease (AD) develops progressive neurodegeneration linked to the formation of proteins aggregates. However, their single actions cannot explain the extent of brain damage observed in this disorder, and the characterization of co-adjuvant involved in the early toxic processes evoked in AD is essential. In this line, quinolinic acid (QUIN) and homocysteine (Hcy) appear to be involved in the AD neuropathogenesis. Herein, we investigate the effects of QUIN and Hcy on early toxic events in cortical neurons and astrocytes. Exposure of primary cortical cultures to these neurometabolites for 24 h induced concentration-dependent neurotoxicity. In addition, QUIN (25 μM) and Hcy (30 μM) triggered ROS production, lipid peroxidation, diminished of Na,K-ATPase activity, and morphologic alterations, culminating in reduced neuronal viability by necrotic cell death. In astrocytes, QUIN (100 μM) and Hcy (30 μM) induced caspase-3-dependent apoptosis and morphologic alterations through oxidative status imbalance. To establish specific mechanisms, we preincubated cell cultures with different protective agents. The combined toxicity of QUIN and Hcy was attenuated by melatonin and Trolox in neurons and by NMDA antagonists and glutathione in astrocytes. Cellular death and morphologic alterations were prevented when co-culture was treated with metabolites, suggesting the activation of protector mechanisms dependent on soluble factors and astrocyte and neuron communication through gap junctions. These findings suggest that early damaging events involved in AD can be magnified by synergistic toxicity of the QUIN and Hcy. Therefore, this study opens new possibilities to elucidate the molecular mechanisms of neuron-astrocyte interactions and their role in neuroprotection against QUIN and Hcy.
受阿尔茨海默病（AD）影响的患者的大脑会发生进行性神经退行性变，这与蛋白质聚集体的形成有关。然而，它们的单一作用并不能解释在这种疾病中观察到的脑损伤程度，因此，对 AD 早期毒性过程中涉及的协同辅助因子的特征描述是至关重要的。在这方面，喹啉酸（QUIN）和同型半胱氨酸（Hcy）似乎与 AD 的神经发病机制有关。在此，我们研究了 QUIN 和 Hcy 对皮质神经元和星形胶质细胞早期毒性事件的影响。将这些神经代谢物暴露于原代皮质培养物中 24 小时会引起浓度依赖性神经毒性。此外，QUIN（25 μM）和 Hcy（30 μM）引发 ROS 产生、脂质过氧化、Na，K-ATP 酶活性降低以及形态改变，最终导致通过坏死性细胞死亡导致神经元活力降低。在星形胶质细胞中，QUIN（100 μM）和 Hcy（30 μM）通过氧化状态失衡诱导 caspase-3 依赖性细胞凋亡和形态改变。为了确定特定的机制，我们用不同的保护剂对细胞培养物进行了预孵育。在神经元中，褪黑素和 Trolox 可减轻 QUIN 和 Hcy 的联合毒性，而在星形胶质细胞中，NMDA 拮抗剂和谷胱甘肽可减轻联合毒性。当用代谢物对共培养物进行处理时，细胞死亡和形态改变得到了预防，这表明激活了依赖于可溶性因子的保护机制以及星形胶质细胞和神经元通过缝隙连接进行通讯的保护机制。这些发现表明，AD 中涉及的早期损伤事件可能会因 QUIN 和 Hcy 的协同毒性而加剧。因此，这项研究为阐明神经元-星形胶质细胞相互作用的分子机制及其在 QUIN 和 Hcy 神经保护中的作用开辟了新的可能性。
