Universidade Federal do Pampa - Campus Uruguaiana, Programa de Pós-Graduação em Bioquímica (PPGBioq), BR-472 Km 7, CEP 97500-970, Uruguaiana, RS, Brazil.
Metallomics. 2019 Feb 20;11(2):362-374. doi: 10.1039/c8mt00268a.
Thimerosal (THIM) is a well-established antifungal and antiseptic agent widely used as a preservative in vaccines. Recent studies identified the neurotoxic effects of THIM, including malfunction of the monoaminergic system. However, the underlying cytotoxic mechanisms are not well understood. Here we used the fruit fly Drosophila melanogaster to investigate the mechanisms of THIM-induced neurotoxicity. We focused on the dopaminergic system, and the rate-limiting enzyme tyrosine hydroxylase (DmTyrH), to test the hypothesis that THIM can impair dopamine (DA) homeostasis and subsequently cause dysfunction. We studied the effect of THIM by feeding 1-2 day old flies (both sexes) food supplemented with 25 μM THIM for 4 days and determined THIM-induced effects on survival, oxidative stress, and metabolic activity based on MTT assay and acetylcholinesterase (AChE) activity. Our results demonstrate that D. melanogaster exposed to THIM present changes in DmTyrH expression and activity, together with altered DA levels that led to impaired motor behavior. These phenotypes were accompanied by an increase in oxidative stress, with a decrease in MTT reduction, in AChE activity, and also in survival rate. These findings suggest an initiating and primary role for THIM-mediated DmTyrH dysfunction that leads to impaired DA function and behavioral abnormalities, ultimately causing oxidative stress-related neurotoxicity.
硫柳汞（THIM）是一种成熟的抗真菌和防腐剂，广泛用作疫苗中的防腐剂。最近的研究确定了 THIM 的神经毒性作用，包括单胺能系统的功能障碍。然而，其潜在的细胞毒性机制尚不清楚。在这里，我们使用黑腹果蝇 Drosophila melanogaster 来研究 THIM 诱导的神经毒性的机制。我们专注于多巴胺能系统和限速酶酪氨酸羟化酶（DmTyrH），以验证 THIM 可以破坏多巴胺（DA）稳态并随后导致功能障碍的假设。我们通过喂食 1-2 天大的果蝇（雌雄同体）含 25μM THIM 的食物来研究 THIM 的作用，持续 4 天，并基于 MTT 测定法和乙酰胆碱酯酶（AChE）活性来确定 THIM 诱导的对生存、氧化应激和代谢活性的影响。我们的结果表明，暴露于 THIM 的 D. melanogaster 表现出 DmTyrH 表达和活性的变化，以及改变的 DA 水平，导致运动行为受损。这些表型伴随着氧化应激的增加，MTT 还原减少，AChE 活性降低，存活率降低。这些发现表明，THIM 介导的 DmTyrH 功能障碍具有起始和主要作用，导致 DA 功能受损和行为异常，最终导致与氧化应激相关的神经毒性。
