AMMONIA NITROGEN AND CADMIUM STRESS ON ANTIOXIDANT SYSTEM AND IMMUNE FUNCTION OF FURONG CRUCIAN CARP (CYPRINUS CAPIO FURONG.♀×CARASSIUS AURATUS RED VAR.♂)

It is widely acknowledged that many diverse contaminants coexisting in aquatic ecosystems, which could contribute to single and/or combined adverse effects to aquatic life. Ammonia nitrogen and cadmium are common toxic contaminants in aqueous environment and have multiple impacts on physiological activity, metabolism and body health of fish. Although some studies about the single or combined toxicity to aquatic organisms were carried out, more reports have been concerned about a certain chemical or the similar kinds of chemicals, such as the heavy metals or the organic contaminant. However, the information of the interactive impacts among distinct types of water pollutants remains unclear. To comprehensively assess the effects of ammonia nitrogen and cadmium on antioxidant system and immune function of juvenile Furong crucian carp (Cyprinus capio furong.♀×Carassius auratus red var.♂), we stimulated subacute exposure by static toxicology experiment, and collected liver tissues at 0, 2, 4, 6 and 8 days after exposure, then determined antioxidative indices and non-specific immunity parameters with hepatic histoenzymology. The results showed that malondialdehyde (MDA) content, the activity of acid phosphatase (ACP) and myeloperoxidase (MPO) increased differently in liver after ammonia nitrogen and/or cadmium exposure. Liver catalase (CAT) activity decreased at first and then increased in all treatment groups. Hepatopancreas superoxide dismutase (SOD), glutathion peroxidase (GSH-PX), alkaline phosphatase (AKP) and glutathione (GSH) increased firstly and then declined. The hepatic SOD and GSH-PX activities were higher than that in control group at 6 days post cadmium exposure, while GSH content was lower than that in control group at 4 days post cadmium exposure. The hepatic AKP activities first descended and then raised to the maximum at 8 days post cadmium exposure. After joint exposure of ammonia nitrogen and cadmium, liver SOD and GSH-PX activities rose remarkably at 6 and 8 days for the combination of ammonia nitrogen and cadmium, and hepatic AKP activity increased dramatically at 8 days, while liver GSH content decreased at first and then increased. These results indicated that ammonia nitrogen and cadmium could induce hepatic oxidative stress, activate the oxidative defense system and enhance the nonspecific immunity in Furong crucian carp. This study provides the basis for investigating the response mechanism of stress physiology and healthy culture in Furong crucian carp.