镉胁迫对团头鲂免疫系统与抗氧化系统的影响

CADMIUM STRESS ON IMMUNE SYSTEM AND ANTIOXIDANT SYSTEM OF MEGALOBRAMA AMBLYCEPHALA

  • 摘要: 为研究镉暴露对团头鲂免疫系统与抗氧化系统的影响, 将团头鲂暴露于浓度为0 (对照组)、0.05、0.10和0.50 mg/L 镉水体中养殖60d, 发现胆囊随镉浓度的增加而变大, 在高浓度镉暴露组(0.50 mg/L Cd)胆囊颜色加深变成墨绿色, 各镉暴露组团头鲂肝脏体指数与脾脏体指数均显著高于对照组, 且脾脏体指数随着镉浓度的增加逐渐升高。团头鲂经0.50 mg/L镉暴露养殖60d, 镉在肠中富集含量最高(240±1.41) mg/kg, 其次是中肾、肝、鳃、脾、头肾、心、精巢、卵巢和脑, 肌肉中镉的含量最低(0.35±0.04) mg/kg。团头鲂经0.50 mg/L镉暴露养殖60d后, 与对照组比较, 体色偏黄; 脾脏肿大, 细胞出现空泡; 肝脏发黑并有出血的症状, 肝窦增宽; 肠绒毛长度变短, 肠壁肌肉层厚度增大; 鳃组织出现动脉瘤, 细胞增生, 鳃小片发生弯曲。血清中谷胱甘肽过氧化物酶(GSH-PX)和总超氧化物歧化酶(SOD)活性随着镉浓度的增加逐渐降低, 溶菌酶(LYS)含量、碱性磷酸酶(AKP)、酸性磷酸酶(ACP)及过氧化氢酶(CAT)活性在低浓度镉暴露组显著升高, 在高浓度镉暴露组呈下降趋势, 且LYS含量、AKP与ACP活性在高浓度镉暴露组(0.50 mg/L)显著性低于对照组。il-6、il-1β、il-10、tnf-αc3基因在头肾、脾脏及肝脏中的表达量随着镉浓度的增加逐渐降低, 肠中tnf-ɑ、c3igm基因及鳃中c3基因的表达量均随着镉浓度的增加逐渐升高, 头肾中igm基因的表达量在低浓度镉暴露组显著升高, 在高浓度镉暴露组显著性降低。研究表明, 低浓度镉诱导团头鲂表现出一定的毒物兴奋效应, 但随着镉浓度增高, 团头鲂解毒与免疫相关组织被损伤, 机体抗氧化与免疫系统被抑制, 镉对团头鲂的抗氧化系统与免疫系统均存在毒性。研究为进一步深入探索镉对鱼类的毒性作用机制提供了基础的实验依据。

     

    Abstract: In order to study the effects of cadmium exposure on antioxidant and nonspecific immune system of Megalobrama amblycephala, fish were subjected to cadmium concentrations of 0 (control group), 0.05, 0.10, and 0.50 mg/L cadmium for 60d. Results indicated an enlargement of the gall bladder proportional to cadmium concentration, with the gall bladder turning dark green at 0.50 mg/L cadmium exposure. Liver and spleen body indices were significantly elevated in all cadmium-exposed groups compared to the control group, with spleen body index rising progressively with cadmium concentration. The highest concentration of cadmium was in the gut (240±1.41) mg/kg, followed by middle kidney (190±2.12) mg/kg, liver (57±1.35) mg/kg, gill (47±1.54) mg/kg, spleen (16±0.27) mg/kg, head kidney (14±0.37) mg/kg, heart (11±0.36) mg/kg, sperm (2.8±0.42) mg/kg, ovary (1.2±0.21) mg/kg, brain (0.65±0.12) mg/kg, and muscle had the lowest Cd content (0.35±0.04) mg/kg after 0.50 mg/L cadmium exposure culture for 60 days. Fish exposed to this concentration exhibited a yellowish body color, spleen swelling with vacuolated cells, blackened liver with bleeding, enlarged liver sinuses, and chaotic structure. Intestinal villi were shorter with thickened muscle layer, while gill lamellae displayed aneurysms, cell proliferation, and curvature. Serum levels of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) decreased gradually with increasing cadmium concentration, while lysozyme (LYS) content and activities of alkaline phosphatase (AKP), acid phosphatase (ACP), and catalase (CAT) initially increased and then decreased. High cadmium exposure group (0.50 mg/L) significantly reduced LYS content, AKP, and ACP activities compared to the control group. The mRNA expression levels of il-6, il-1β, il-10, tnf-ɑ and c3 genes in head kidney, spleen, and liver decreased with rising cadmium concentration, while tnf-ɑ, c3, and igm gene expression in the intestine, and c3 genes expression in the gill increased. Expression of the igm gene in head kidney significantly increased at low cadmium concentrations but decreased at high concentrations. The results demonstrated that low cadmium levels induced toxic excitability in Megalobrama amblycephala, but higher concentrations damaged immune tissue and inhibited the immune system. Cadmium exerts toxic on both the antioxidant and the immune system of Megalobrama amblycephala, providing a basic experimental data for further exploring the toxic mechanism of cadmium on fish.

     

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