EGCG alleviated 2,4-D-induced cardiovascular toxicity in zebrafish embryos via Nrf2 and p53 pathways

Abstract

2,4-Dichlorophenoxyacetic acid (2,4-D), a widely used herbicide in cultivation, exhibits strong cardiotoxicity to living organisms, thus shows high risks to human health. Epigallocatechin gallate (EGCG), a type of catechin largely found in tea, is well-known for its antioxidant, antiapoptotic, and cardiovascular protective properties. Neverthless, the potential protective effects of EGCG against 2,4-D-induced cardiotoxicity remain underexplored to date. In this study, zebrafish embryos were exposed to 50 mg/L 2,4-D supplemented with 2 μM EGCG until 96 h post-fertilization (hpf) and the morphology observation, biochemical assays, and gene expression analyses were applied to evaluate the role of EGCG against 2,4-D toxicity. The results showed that EGCG significantly restored the 2,4-D-induced cardiovascular impairments including pericardial edema, and abnormal heart structure, heart rate and erythropenia. Q-PCR analysis revealed that EGCG markedly reversed the 2,4-D-dysregulated key cardiac development genes nkx2.5, vegf, vmhc, amhc, hand2 and gata4, except for tbx2b, which remained unchanged. EGCG also counteracted 2,4-D-induced oxidative stress by elevating antioxidant enzymes activities and nonenzyme antioxidant content, resulting in the reduction of malondialdehyde (MDA) and reactive oxygen species (ROS) in 2,4-D group. Furthermore, EGCG modulated the expression of antioxidant defense-related genes Nrf2, sod1, cat, gpx1a and gstm and mitigated the harsh effects of 2,4-D. Moreover, EGCG effectively inhibited 2,4-D-stimulated cellular apoptosis through down-regulation of pro-apoptotic genes of p53, caspase-9, caspase-3 and bax and up-regulation of anti-apoptotic gene bcl-2. In conclusion, EGCG can alleviate 2,4-D-induced cardiovascular toxicity in zebrafish embryos through the nrf2-regulated antioxidant pathway and p53-regulated apoptotic pathway.