Department of Clinical Analyses, Federal University of Santa Catarina, Florianopolis 88040-900 Santa Catarina, Brazil.
Department of Biochemistry, Federal University of Santa Catarina, Florianopolis 88040-900 Santa Catarina, Brazil.
Chem Res Toxicol. 2024 Aug 19;37(8):1269-1282. doi: 10.1021/acs.chemrestox.3c00389. Epub 2024 Jul 26.
Epidemiological and experimental studies have demonstrated that combined exposure to the pesticides paraquat (PQ) and maneb (MB) increases the risk of developing Parkinson's disease. However, the mechanisms mediating the toxicity induced by combined exposure to these pesticides are not well understood. The aim of this study was to investigate the mechanism(s) of neurotoxicity induced by exposure to the pesticides PQ and MB isolated or in association (PQ + MB) in SH-SY5Y neuroblastoma cells. PQ + MB exposure for 24 and 48 h decreased cell viability and disrupted cell membrane integrity. In addition, PQ + MB exposure for 12 h decreased the mitochondrial membrane potential. PQ alone increased reactive oxygen species (ROS) and superoxide anion generation and decreased the activity of mitochondrial complexes I and II at 12 h of exposure. MB alone increased ROS generation and depleted intracellular glutathione (GSH) within 6 h of exposure. In contrast, MB exposure for 12 h increased the GSH levels, the glutamate cysteine ligase (GCL, the rate-limiting enzyme in the GSH synthesis pathway) activity, and increased nuclear Nrf2 staining. Pretreatment with buthionine sulfoximine (BSO, a GCL inhibitor) abolished the MB-mediated GSH increase, indicating that MB increases GSH synthesis by upregulating GCL, probably by the activation of the Nrf2/ARE pathway. BSO pretreatment, which did not modify cell viability per se, rendered cells more sensitive to MB-induced toxicity. In contrast, treatment with the antioxidant -acetylcysteine protected cells from MB-induced toxicity. These findings show that the combined exposure of SH-SY5Y cells to PQ and MB induced a cytotoxic effect higher than that observed when cells were subjected to individual exposures. Such a higher effect seems to be related to additive toxic events resulting from PQ and MB exposures. Thus, our study contributes to a better understanding of the toxicity of PQ and MB in combined exposures.
流行病学和实验研究表明，百草枯（PQ）和代森锰（MB）联合暴露会增加帕金森病的发病风险。然而，联合暴露于这些农药引起毒性的机制尚不清楚。本研究旨在研究 PQ 和 MB 单独或联合（PQ + MB）暴露于 SH-SY5Y 神经母细胞瘤细胞中诱导神经毒性的机制。PQ + MB 暴露 24 和 48 小时会降低细胞活力并破坏细胞膜完整性。此外，PQ + MB 暴露 12 小时会降低线粒体膜电位。PQ 单独暴露 12 小时会增加活性氧（ROS）和超氧阴离子的生成，并降低线粒体复合物 I 和 II 的活性。MB 单独暴露 6 小时会增加 ROS 的生成并耗竭细胞内谷胱甘肽（GSH）。相反，MB 暴露 12 小时会增加 GSH 水平、谷氨酸半胱氨酸连接酶（GCL，GSH 合成途径中的限速酶）的活性，并增加核 Nrf2 染色。用丁硫氨酸亚砜胺（BSO，GCL 抑制剂）预处理会消除 MB 介导的 GSH 增加，表明 MB 通过上调 GCL 增加 GSH 合成，可能通过激活 Nrf2/ARE 途径。BSO 预处理本身不会改变细胞活力，但会使细胞对 MB 诱导的毒性更敏感。相反，抗氧化剂 -乙酰半胱氨酸处理可保护细胞免受 MB 诱导的毒性。这些发现表明，SH-SY5Y 细胞同时暴露于 PQ 和 MB 会引起比单独暴露时更高的细胞毒性效应。这种更高的效应似乎与 PQ 和 MB 暴露引起的相加毒性事件有关。因此，我们的研究有助于更好地理解 PQ 和 MB 在联合暴露中的毒性。
