Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
Neurogenesis Research Group, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
Oxid Med Cell Longev. 2022 Jul 15;2022:1596362. doi: 10.1155/2022/1596362. eCollection 2022.
Previous studies have revealed that the side effects of anticancer drugs induce a decrease of neurogenesis. Methotrexate (MTX), one of anticancer drugs, can induce lipid peroxidation as an indicator of oxidative stress in the brain. Melatonin has been presented as an antioxidant that can prevent oxidative stress-induced neuronal damage via the activation of antioxidant enzymes associated with the increase of neurogenesis. The aims of the present study are to examine the neuroprotective effect of melatonin on the neurotoxicity of MTX on neurogenesis and the changes of protein expression and antioxidant enzyme levels in adult rat hippocampus and prefrontal cortex (PFC). Male Sprague-Dawley rats were assigned into four groups: vehicle, MTX, melatonin, and melatonin+MTX groups. The vehicle group received saline solution and 10% ethanol solution, whereas the experimental groups received MTX (75 mg/kg, i.v.) and melatonin (8 mg/kg, i.p.) treatments. After the animal examination, the brains were removed for p21 immunofluorescence staining. The hippocampus and PFC were harvested for Western blot analysis and biochemical assessments of malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD). The immunofluorescence result showed that coadministration with melatonin diminished p21-positive cells in the hippocampal dentate gyrus, indicating a decrease of cell cycle arrest. Melatonin reduced the levels of MDA and prevented the decline of antioxidant enzyme activities in rats receiving MTX. In the melatonin+MTX group, the protein expression results showed that melatonin treatment significantly upregulated synaptic plasticity and an immature neuron marker through enhancing brain derived neurotrophic factor (BDNF) and doublecortin (DCX), respectively. Moreover, melatonin ameliorated the antioxidant defense system by improving the nuclear factor erythroid 2-related factor 2 (Nrf2) in rats receiving MTX. These findings suggested that the effects of melatonin can ameliorate MTX toxicity by several mechanisms, including an increase of endogenous antioxidants and neurogenesis in adult rat hippocampus and PFC.
先前的研究表明，抗癌药物的副作用会导致神经发生减少。甲氨蝶呤（MTX）是一种抗癌药物，可引起脂质过氧化作为大脑氧化应激的指标。褪黑素已被证明是一种抗氧化剂，可通过激活与神经发生增加相关的抗氧化酶来预防氧化应激诱导的神经元损伤。本研究的目的是研究褪黑素对 MTX 神经毒性的神经保护作用，以及褪黑素对成年大鼠海马和前额叶皮质（PFC）神经发生、蛋白质表达和抗氧化酶水平变化的影响。雄性 Sprague-Dawley 大鼠分为四组：对照组、MTX 组、褪黑素组和褪黑素+MTX 组。对照组给予生理盐水和 10%乙醇溶液，实验组给予 MTX（75mg/kg，静脉注射）和褪黑素（8mg/kg，腹腔注射）处理。动物检查后，取出大脑进行 p21 免疫荧光染色。提取海马和前额叶皮质进行 Western blot 分析和丙二醛（MDA）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPX）和超氧化物歧化酶（SOD）的生化评估。免疫荧光结果显示，褪黑素共给药可减少海马齿状回中 p21 阳性细胞，表明细胞周期阻滞减少。褪黑素降低 MDA 水平，并防止接受 MTX 治疗的大鼠抗氧化酶活性下降。在褪黑素+MTX 组中，褪黑素处理通过分别增强脑源性神经营养因子（BDNF）和双皮质素（DCX），使突触可塑性和未成熟神经元标志物的蛋白表达结果显著上调。此外，褪黑素通过改善核因子红细胞 2 相关因子 2（Nrf2）改善了接受 MTX 治疗的大鼠的抗氧化防御系统。这些发现表明，褪黑素的作用可以通过多种机制改善 MTX 毒性，包括增加成年大鼠海马和 PFC 中的内源性抗氧化剂和神经发生。
