List of metabolites from rat myocardium tissues in both MTX treated and untreated conditions

Cardiotoxicity is a well-established adverse effect of several drugs across multiple therapeutic indications. It is particularly prevalent following anticancer therapy. In order to evaluate the changes in metabolism associated with cardiotoxicity, we treated Wistar rats with a single high dose of methotrexate, and after five days, the animals were sacrificed. We then analyzed the cardiotoxicity parameters in serum and cardiac tissue with the goal of identifying a metabolic signature of cardiotoxicity using discovery-based metabolomics. The results showed a total of 95 metabolites that were found to be significantly (p < 0.05) modulated: either up- or downregulated in the HDMTX-treated group when compared with the control group. Based on these metabolites, it was found via integrated pathway analysis that a majority of the metabolites were associated with many important cardiac tissue metabolic pathways, such as the malate aspartate shuttle, taurine and hypotaurine metabolism, betaine metabolism, spermidine and spermine biosynthesis, and homocysteine degradation. Among them, L-arginine, homocysteine, and betaine were significantly upregulated, suggesting their role in cardiac tissue injury. The metabolic signature of toxicity may offer a novel approach to the prediction of elevated betaine levels as the novel biomarker for cardiotoxic potential due to HDMTX cardiac toxicity.心脏毒性（cardiotoxicity）是多种药物在不同治疗适应证中已被证实的不良反应，在抗肿瘤治疗后尤为高发。为评估与心脏毒性相关的代谢变化，本研究对Wistar大鼠给予单次高剂量甲氨蝶呤（methotrexate），于给药5天后处死动物。随后通过发现型代谢组学（discovery-based metabolomics）技术分析血清与心脏组织中的心脏毒性相关参数，旨在挖掘心脏毒性的代谢特征谱。 研究结果显示，与对照组相比，高剂量甲氨蝶呤（HDMTX）处理组中共检测到95种代谢物发生显著（p < 0.05）表达调控，即出现上调或下调变化。基于上述差异代谢物，通过整合通路分析发现，大部分代谢物与多种关键心脏组织代谢通路密切相关，包括苹果酸-天冬氨酸穿梭（malate aspartate shuttle）、牛磺酸与次牛磺酸代谢、甜菜碱代谢、亚精胺与精胺生物合成以及同型半胱氨酸降解。其中，L-精氨酸、同型半胱氨酸与甜菜碱均显著上调，提示其在心脏组织损伤中发挥潜在作用。该毒性代谢特征谱可为以甜菜碱水平升高作为新型生物标志物（biomarker），预测高剂量甲氨蝶呤相关心脏毒性风险提供全新的研究方向。