Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by selective degeneration of motor neurons. The primary triggers for motor neuronal death are still unknown, but inflammation is considered to be an important factor contributing to the pathophysiology of ALS both clinically and in ALS models. Prostaglandin E2 (PGE2) and its corresponding four E-prostanoid receptors play a pivotal role in the degeneration of motor neurons in human and transgenic models of ALS. It has also been shown that PGE2-EP2 signaling in glial cells (astrocytes or microglia) promotes motor neuronal death in G93A mice. The present study was designed to investigate the levels of expression of EP receptors in the spinal motor neurons of ALS model mice and to examine whether PGE2 alters the expression of EP receptors in differentiated NSC-34 cells, a motor neuron-like cell line. Immunohistochemical staining demonstrated that EP2 and EP3 immunoreactivity was localized in NeuN-positive large cells showing the typical morphology of motor neurons in mice. Semi-quantitative analysis showed that the immunoreactivity of EP2 in motor neurons was significantly increased in the early symptomatic stage in ALS model mice. In contrast, the level of EP3 expression remained constant, irrespective of age. In differentiated NSC-34 cells, bath application of PGE2 resulted in a concentration-dependent decrease of MTT reduction. Although PGE2 had no effect on cell survival at concentrations of less than 10 μM, pretreatment with 10 μM PGE2 significantly up-regulated EP2 and concomitantly potentiated cell death induced by 30 μM PGE2. These results suggest that PGE2 is an important effector for induction of the EP2 subtype in differentiated NSC-34 cells, and that not only EP2 up-regulation in glial cells but also EP2 up-regulation in motor neurons plays a pivotal role in the vulnerability of motor neurons in ALS model mice.

肌萎缩性侧索硬化症（ALS）是一种以运动神经元选择性变性为特征的进行性神经退行性疾病。运动神经元死亡的主要诱因仍是未知的，但是炎症被认为是在临床上和在ALS模型中都有助于ALS病理生理的重要因素。前列腺素E2（PGE2）及其相应的四个E-前列腺素受体在人和转基因ALS模型中，在运动神经元变性中起关键作用。还已经显示，神经胶质细胞（星形胶质细胞或小胶质细胞）中的PGE2-EP2信号传导可促进G93A小鼠的运动神经元死亡。本研究旨在研究ALS模型小鼠脊柱运动神经元中EP受体的表达水平，并检查PGE2是否会改变分化的NSC-34细胞（一种运动神经元样细胞系）中EP受体的表达。免疫组织化学染色表明，EP2和EP3免疫反应性位于NeuN阳性大细胞中，显示了小鼠运动神经元的典型形态。半定量分析表明，在ALS模型小鼠的症状早期，EP2在运动神经元中的免疫反应性显着增加。相反，EP3表达水平保持恒定，与年龄无关。在分化的NSC-34细胞中，PGE2的浸浴导致MTT降低的浓度依赖性降低。尽管PGE2在浓度低于10μM时对细胞存活无影响，但用10μMPGE2预处理可显着上调EP2，并同时增强30μMPGE2诱导的细胞死亡。这些结果表明，PGE2是诱导分化的NSC-34细胞中EP2亚型的重要效应子，不仅神经胶质细胞中EP2上调，而且运动神经元中EP2上调在神经元易感性中也起着关键作用。 ALS模型小鼠中的运动神经元。