Increasing attention has been paid in the past decade to assessing the toxicological effects of nanoparticles and finding a protectant; thus, the current study aimed to investigate the protective effect of the mitochondria-targeting drug methylene blue (MB) against copper oxide nanoparticle (CuO-NP)-induced neurobehavioral toxicity in rats. For this purpose, twenty rats were allocated to four equal groups (n = 5). The negative control group received distilled water intraperitoneally (IP) and Tween 80 (10 %) orally. The CuO-NP group was given a dose of 100 mg/kg of CuO-NPs, administered orally, and the positive control group was treated with 1 mg/kg MB intraperitoneally (IP). The final group was concurrently exposed to CuO-NPs and MB for 14 consecutive days. At the end of the study, each group was neurobehaviorally blind tested relative to other experimental animals, then brain tissue markers were determined and a histopathological examination was conducted. The results showed that supplementation with CuO-NPs induced neurobehavioral alterations; increased Cu content in the brain; and enhanced lipid peroxidation (malondialdehyde [MDA]), protein peroxidation (protein carbonyl [PC]), and DNA oxidative damage (8-hydroxy-2-deoxyguanosine [8−OH-dG]) compared to other treatments. In addition, a decrease was noted in the mitochondrial dehydrogenases’ (aldehyde dehydrogenase 2 [ALDH2], and glutamate dehydrogenase [GDH]) activity in Cu-exposed rats. The histopathological findings revealed shrunken, pyknotic, and hypereosinophic cortical neurons and increased immune positive brown staining of caspase-3 protein, indicating apoptosis. Co-treatment with methylene blue ameliorated the neurotoxic effects of CuO-NPs; therefore, MB evidently had a powerful modulatory effect against the neurotoxicity of nano-Cu oxide via its antioxidant and mitochondrial protection properties.

在过去的十年中，人们越来越关注评估纳米颗粒的毒理学效应和寻找保护剂；因此，目前的研究旨在研究线粒体靶向药物亚甲蓝 (MB) 对氧化铜纳米颗粒 (CuO-NP) 诱导的大鼠神经行为毒性的保护作用。为此，二十只大鼠被分配到四个相等的组 (n = 5)。阴性对照组腹腔注射蒸馏水 (IP) 和口服吐温 80 (10%)。CuO-NP 组口服 100 mg/kg CuO-NPs，阳性对照组腹腔注射 1 mg/kg MB。最后一组连续 14 天同时暴露于 CuO-NPs 和 MB。在研究结束时，各组相对于其他实验动物进行神经行为盲测，然后测定脑组织标志物并进行组织病理学检查。结果表明，补充 CuO-NPs 会引起神经行为改变；增加大脑中的铜含量；与其他治疗相比，脂质过氧化（丙二醛 [MDA]）、蛋白质过氧化（蛋白质羰基 [PC]）和 DNA 氧化损伤（8-羟基-2-脱氧鸟苷 [8-OH-dG]）增强。此外，Cu 暴露大鼠的线粒体脱氢酶（醛脱氢酶 2 [ALDH2] 和谷氨酸脱氢酶 [GDH]）活性降低。组织病理学结果显示皮层神经元萎缩、固缩和嗜酸性粒细胞增多，caspase-3 蛋白的免疫阳性棕色染色增加，表明细胞凋亡。与亚甲蓝共同处理改善了 CuO-NPs 的神经毒性作用；因此，MB 通过其抗氧化和线粒体保护特性，显然对纳米氧化铜的神经毒性具有强大的调节作用。