Molecular Mechanisms of Quercetin in Regulating Antioxidant Defense and Pyroptosis Pathways in the Redclaw Crayfish (Cherax quadricarinatus)

As a principal species in freshwater aquaculture, the redclaw crayfish (Cherax quadricarinatus) depends on a competent immune system to mitigate environmental and pathogenic challenges. Quercetin, a ubiquitous plant-derived flavonoid, has garnered scientific attention due to its pleiotropic bioactivities, including antioxidant, anti-inflammatory, and immunomodulatory properties. This study investigated the effects of waterborne quercetin exposure on transcriptional regulation and antioxidant capacity in C. quadricarinatus. Over a 28-day period, crayfish were subjected to five quercetin concentrations (0, 1.0, 2.5, 5.0, and 10.0 mg/L), with outcomes evaluated against an untreated control. At the concentration of 5.0 mg/L, which showed the most pronounced effects among the tested concentrations, quercetin exposure was associated with significant downregulation of key transcripts in the NLRP3 inflammasome pathway (NLRP3, GSDMD, Caspase-1), as evidenced by the downregulation of NLRP3, GSDMD, and Caspase-1. Simultaneously, the transcriptional changes were consistent with the modulation/activation of the Nrf2 signaling axis, upregulating the expression of Nrf2, NQO1, and Keap1. These transcriptional changes indicate that quercetin attenuates pyroptosis and augments cellular antioxidant defenses via the Nrf2-Keap1 cascade. Correspondingly, the hepatopancreas displayed markedly elevated activities of SOD, CAT, and GSH-Px, accompanied by a significant reduction in MDA levels, indicating enhanced antioxidative capacity and diminished lipid peroxidation. This study provides valuable toxicological insights and elucidates part of the molecular basis for quercetin's immunomodulatory and antioxidant roles in freshwater crustaceans.作为淡水养殖的核心品种，红螯螯虾（Cherax quadricarinatus）依赖完善的免疫系统以抵御环境胁迫与病原侵袭。槲皮素（Quercetin）是一种广泛分布于植物中的黄酮类化合物，因其兼具抗氧化、抗炎及免疫调节等多效生物活性而受到学界广泛关注。本研究探讨了水体暴露槲皮素对红螯螯虾转录调控与抗氧化能力的影响。实验周期为28天，设置5个槲皮素暴露浓度组（0、1.0、2.5、5.0及10.0 mg/L），并以未处理组为对照评估实验结果。在所有受试浓度中，5.0 mg/L组的调控效果最为显著：该浓度下槲皮素暴露可显著下调NLRP3炎症小体通路（NLRP3、GSDMD、Caspase-1）中的关键转录本表达，具体体现为NLRP3、GSDMD及Caspase-1的转录水平降低。与此同时，转录组变化与Nrf2信号轴的调控/激活状态相一致，上调了Nrf2、NQO1及Keap1的基因表达。上述转录变化表明，槲皮素可通过Nrf2-Keap1级联反应抑制细胞焦亡并增强细胞抗氧化防御能力。相应地，肝胰腺中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）及谷胱甘肽过氧化物酶（GSH-Px）的活性显著升高，同时丙二醛（MDA）水平显著降低，提示机体抗氧化能力增强且脂质过氧化反应受到抑制。本研究为槲皮素在淡水甲壳动物中的免疫调节与抗氧化作用提供了宝贵的毒理学见解，并阐明了其部分分子机制。