While chromium (Cr) has been recognized as an essential nutrient for all animals, and dietary supplementation can be beneficial, it can also be toxic. The present study aimed to investigate the contrasting effects of dietary chromium in Pacific white shrimp Litopenaeus vannamei. Five experimental diets were formulated to contain Cr at levels of 0.82 (Cr0.82, unsupplemented diet), 1.01 (Cr1.01), 1.22 (Cu1.22), 1.43 (Cr1.43) and 1.63 (Cr1.63) mg/kg and were fed to shrimp for 8 weeks. Highest weight gain was recorded in shrimp fed the diet containing 1.22 mg/kg Cr. Shrimp fed the diet containing the highest level of Cr (1.63 mg/kg) showed the lowest weight gain and clear signs of oxidative stress and apoptosis as evidenced by higher levels of H₂O₂, malondialdehyde and 8-hydroxydeoxyguanosine, and expression of caspase 2, 3, 5, and lower contents of total and oxidized glutathione, and expression of Cu/Zn sod, cat, gpx, mt, bcl2. Chromium supplementation promoted glycolysis and inhibited gluconeogenesis as shown by increased activities of hexokinase, phosphofructokinase and pyruvate kinase, and reduced activity of phosphoenolpyruvate carboxykinase in shrimp fed the diet containing 1.43 mg/kg Cr. Shrimp fed the diet with 1.63 mg/kg Cr had lowest contents of crustacean hyperglycemic hormone and insulin like peptide in hemolymph. Expression of genes involved in insulin signaling pathway and glycose metabolism including insr, irs1, pik3ca, pdpk1, akt, acc1, gys, glut1, pk, hk were up-regulated, and foxO1, gsk-3β, g6pc, pepck were down-regulated in shrimp fed the diets supplemented with Cr. This study demonstrated that optimum dietary supplementation of Cr had beneficial effects on glucose homeostasis and growth, whereas excess caused oxidative damage and impaired growth. The results contribute to our understanding of the biological functions of chromium in shrimp.

虽然铬 (Cr) 已被公认为所有动物的必需营养素，但膳食补充剂可能有益，但也可能有毒。本研究旨在调查日粮铬对南美白对虾的对比影响。五种实验日粮被配制为含有 0.82（Cr0.82，未补充日粮）、1.01（Cr1.01）、1.22（Cu1.22）、1.43（Cr1.43）和 1.63（Cr1.63）mg/ kg，喂给虾8周。在喂食含有 1.22 mg/kg Cr 的饮食的虾中记录到的体重增加最高。喂食含最高铬 (1.63 mg/kg) 饮食的虾表现出最低的增重和明显的氧化应激和细胞凋亡迹象，如较高水平的 H ₂ O ₂所证明的、丙二醛和 8-羟基脱氧鸟苷、半胱天冬酶 2、3、5 的表达，以及较低含量的总谷胱甘肽和氧化型谷胱甘肽，以及 Cu/Zn sod、cat、gpx、mt、bcl2 的表达。铬的补充促进了糖酵解并抑制了糖异生，如己糖激酶、磷酸果糖激酶和丙酮酸激酶的活性增加以及磷酸烯醇式丙酮酸羧激酶的活性降低所表明的，在饲喂含 1.43 mg/kg Cr 的饲料的虾中。以 1.63 mg/kg Cr 喂食的虾的血淋巴中甲壳类高血糖激素和胰岛素样肽含量最低。胰岛素信号通路和糖代谢相关基因insr、irs1、pik3ca、pdpk1、akt、acc1、gys、glut1、pk、hk表达上调，foxO1、gsk-3β、g6pc、pepck下调在喂食添加 Cr 的饲料的虾中。该研究表明，最佳膳食补充铬对葡萄糖稳态和生长有益，而过量会导致氧化损伤和生长受损。这些结果有助于我们了解铬在虾中的生物学功能。