Engin Ayse Basak, Engin Evren Doruk, Golokhvast Kirill, Spandidos Demetrios A, Tsatsakis Aristides M
Department of Toxicology, Faculty of Pharmacy, Gazi University, Ankara 06330, Turkey.
Institute of Biotechnology, Ankara University, Ankara 06110, Turkey.
Int J Mol Med. 2017 May;39(5):1215-1223. doi: 10.3892/ijmm.2017.2937. Epub 2017 Mar 27.
The molecular mechanisms mediating mercury‑induced neurotoxicity are not yet completely understood. Thus, the aim of this study was to investigate whether the severity of MeHg‑ and HgCl2‑mediated cytotoxicity to SH‑SY5Y human dopaminergic neurons can be attenuated by regulating glutamate‑mediated signal‑transmission through caffeine and interferon‑γ (IFN‑γ). The SH‑SY5Y cells were exposed to 1, 2 and 5 µM of either MeHgCl2 or HgCl2 in the presence or absence of L‑glutamine. To examine the effect of adenosine receptor antagonist, the cells were treated with 10 and 20 µM caffeine. The total mitochondrial metabolic activity and oxidative stress intensity coefficient were determined in the 1 ng/ml IFN‑γ‑ and glutamate‑stimulated SH‑SY5Y cells. Following exposure to mercury, the concentration‑dependent decrease in mitochondrial metabolic activity inversely correlated with oxidative stress intensity. MeHg was more toxic than HgCl2. Mercury‑induced neuronal death was dependent on glutamate‑mediated excitotoxicity. Caffeine reduced the mercury‑induced oxidative stress in glutamine-containing medium. IFN‑γ treatment decreased cell viability and increased oxidative stress in glutamine‑free medium, despite caffeine supplementation. Although caffeine exerted a protective effect against MeHg-induced toxicity with glutamate transmission, under co‑stimulation with glutamine and IFN‑γ, caffeine decreased the MeHg‑induced average oxidative stress only by half. Thereby, our data indicate that the IFN‑γ stimulation of mercury‑exposed dopaminergic neurons in neuroinflammatory diseases may diminish the neuroprotective effects of caffeine.
介导汞诱导神经毒性的分子机制尚未完全明确。因此，本研究旨在探讨通过咖啡因和干扰素-γ（IFN-γ）调节谷氨酸介导的信号传递，是否可以减轻甲基汞（MeHg）和氯化汞（HgCl2）对SH-SY5Y人多巴胺能神经元的细胞毒性。在存在或不存在L-谷氨酰胺的情况下，将SH-SY5Y细胞暴露于1、2和5μM的MeHgCl2或HgCl2中。为了检测腺苷受体拮抗剂的作用，用10和20μM咖啡因处理细胞。在1 ng/ml IFN-γ和谷氨酸刺激的SH-SY5Y细胞中测定线粒体总代谢活性和氧化应激强度系数。暴露于汞后，线粒体代谢活性的浓度依赖性降低与氧化应激强度呈负相关。MeHg比HgCl2毒性更大。汞诱导的神经元死亡依赖于谷氨酸介导的兴奋性毒性。咖啡因可降低含谷氨酰胺培养基中汞诱导的氧化应激。尽管添加了咖啡因，但IFN-γ处理在无谷氨酰胺培养基中降低了细胞活力并增加了氧化应激。虽然咖啡因在谷氨酸传递过程中对MeHg诱导的毒性发挥了保护作用，但在谷氨酰胺和IFN-γ共同刺激下，咖啡因仅将MeHg诱导的平均氧化应激降低了一半。因此，我们的数据表明，在神经炎症性疾病中，IFN-γ对汞暴露的多巴胺能神经元的刺激可能会削弱咖啡因的神经保护作用。
