Toxicology Division, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, 226031, India.
Department of Biochemistry and Biophysics, Helen Diller Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA.
Neurotox Res. 2018 Aug;34(2):198-219. doi: 10.1007/s12640-018-9878-2. Epub 2018 Mar 12.
Piracetam, a nootropic drug, has been clinically used for decades; however, its mechanism of action still remains enigmatic. The present study was undertaken to evaluate the role of mitochondrion-specific factors of caspase-independent pathway like apoptotic-inducing factor (AIF) and endonuclease-G (endo-G) in piracetam-induced neuroprotection. N2A cells treated with lipopolysaccharide (LPS) exhibited significant cytotoxicity, impaired mitochondrial activity, and reactive oxygen species generation which was significantly attenuated with piracetam co-treatment. Cells co-treated with LPS and piracetam exhibited significant uptake of piracetam in comparison to only piracetam-treated cells as estimated by liquid chromatography-mass spectrometry (LC-MSMS). LPS treatment caused significant translocation of AIF and endonuclease-G in neuronal N2A cells which were significantly attenuated with piracetam co-treatment. Significant over-expression of proinflammatory cytokines was also observed after treatment of LPS to cells which was inhibited with piracetam co-treatment demonstrating its anti-inflammatory property. LPS-treated cells exhibited significant oxidative DNA fragmentation and poly [ADP-ribose] polymerase-1 (PARP-1) up-regulation in nucleus, both of which were attenuated with piracetam treatment. Antioxidant melatonin but not z-VAD offered the inhibited LPS-induced DNA fragmentation indicating the involvement of oxidative DNA fragmentation. Further, we did not observe the altered caspase-3 level after LPS treatment initially while at a later time point, significantly augmented level of caspase-3 was observed which was not inhibited with piracetam treatment. In total, our findings indicate the interference of piracetam in mitochondrion-mediated caspase-independent pathway, as well as its anti-inflammatory and antioxidative properties. Graphical Abstract Graphical abstract indicating the novel interference of metabolic enhancer piracetam (P) in neuronal death mechanisms.
吡拉西坦是一种益智药，已临床应用数十年，但作用机制仍不清楚。本研究旨在评估线粒体特异性因子胱天蛋白酶非依赖性途径中的凋亡诱导因子（AIF）和核酸内切酶-G（endo-G）在吡拉西坦诱导的神经保护中的作用。用脂多糖（LPS）处理的 N2A 细胞表现出明显的细胞毒性、线粒体活性受损和活性氧生成，而用吡拉西坦共同处理则显著减轻了这些损伤。与仅用吡拉西坦处理的细胞相比，用 LPS 和吡拉西坦共同处理的细胞表现出明显的吡拉西坦摄取，这通过液相色谱-质谱联用（LC-MSMS）进行了估计。LPS 处理导致神经元 N2A 细胞中 AIF 和核酸内切酶-G 的明显易位，而用吡拉西坦共同处理则显著减轻了这种易位。用 LPS 处理细胞还观察到促炎细胞因子的显著过表达，而用吡拉西坦共同处理则抑制了这种过表达，证明了其抗炎特性。LPS 处理的细胞在细胞核中表现出明显的氧化 DNA 片段化和多聚 [ADP-核糖] 聚合酶-1（PARP-1）上调，这两种情况均因吡拉西坦处理而减轻。抗氧化剂褪黑素而不是 z-VAD 提供了抑制 LPS 诱导的 DNA 片段化，表明涉及氧化 DNA 片段化。此外，我们最初没有观察到 LPS 处理后 caspase-3 水平的改变，而在稍后的时间点，观察到 caspase-3 水平显著增加，但吡拉西坦处理并未抑制其增加。总之，我们的研究结果表明，吡拉西坦干扰了线粒体介导的胱天蛋白酶非依赖性途径，以及其抗炎和抗氧化特性。
