The anti-inflammatory activity of the guava leaf extracts (GLE) against LPS-induced inflammatory responses in fish macrophage cell lines is well documented. Here, we evaluated the effects of dietary GLE on LPS-induced oxidative stress, immune responses, and glucocorticoid receptor-related gene expression in Cyprinus carpio. Basal diet was supplemented with 0 (control), 100, 150, 200, or 250 mg kg⁻¹ GLE for eight weeks. Highest (p < 0.05) weight gain rate was obtained in fish group supplemented with 200 mg kg⁻¹ of GLE. The results showed that superoxide dismutase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, lysozyme, and complement C3 decreased, while malondialdehyde level increased in the liver and spleen upon LPS-challenge. Dietary GLE supplementation (especially 200 or 250 mg kg⁻¹) alleviated LPS-induced changes. Similarly, GLE (150–250 mg kg⁻¹) reversed LPS-induced alteration of serum biochemical parameters such as alkaline phosphatase, aspartate transaminase, alanine transaminase, and myeloperoxidase. LPS treatment markedly induced increased the mRNA levels of TNF-α, IL-1β, and NF-κB p65 in both the liver and kidney tissues; however, GLE pre-treatment attenuated LPS-induced elicitation of TNF-α, IL-β, and NF-κB p65. Moreover, dietary GLE supplementation significantly increased the expression of HSP70 and HSP90, and glucocorticoid receptor in the liver and kidney after LPS challenge. Thus, GLE attenuated LPS-induced inflammation response by up-regulating glucocorticoid receptor-related gene expression in carp. Finally, GLE supplementation reduced carp mortality after LPS-challenge. These results suggest that dietary supplementation with 200 mg kg⁻¹ GLE is adequate for effectively attenuating LPS-induced oxidative stress and immune-suppressive effects in C. carpio.

番石榴叶提取物（GLE）对LPS诱导的鱼巨噬细胞细胞系炎症反应的抗炎活性已得到充分证明。在这里，我们评估了膳食GLE对鲤鱼中LPS诱导的氧化应激，免疫反应和糖皮质激素受体相关基因表达的影响。基础饮食中补充了0（对照组）， 100、150、200或250 mg kg ^-1 GLE八周。 补充200 mg kg ^-1的鱼组获得最高（p <0.05）增重率GLE。结果表明，LPS攻击后，肝脏和脾脏中的超氧化物歧化酶，谷胱甘肽S-转移酶，谷胱甘肽过氧化物酶，谷胱甘肽还原酶，溶菌酶和补体C3降低，而丙二醛水平升高。饮食中补充GLE（特别是200或250 mg kg ^-1）可减轻LPS引起的变化。同样，GLE（150–250 mg kg ^-1）逆转了LPS诱导的血清生化参数的改变，例如碱性磷酸酶，天冬氨酸转氨酶，丙氨酸转氨酶和髓过氧化物酶。LPS处理可明显诱导肝和肾组织中TNF-α，IL-1β和NF-κBp65 mRNA的表达增加；然而，GLE预处理减弱了LPS诱导的TNF-α，IL-β和NF-κBp65诱导。此外，在LPS攻击后，膳食GLE补充剂显着增加了肝脏和肾脏中HSP70和HSP90的表达以及糖皮质激素受体。因此，GLE通过上调鲤鱼糖皮质激素受体相关基因的表达来减弱LPS诱导的炎症反应。最后，补充GLE可降低LPS攻击后鲤鱼的死亡率。这些结果表明饮食补充200 mg kg ^-1 GLE足以有效减轻LPC诱导的鲤鱼的氧化应激和免疫抑制作用。