Dietary Aroclor 1254-Induced Toxicity on Antioxidant Capacity, Immunity and Energy Metabolism in Chinese Mitten Crab Eriocheir sinensis: Amelioration by Vitamin A.

Erchao Li,Xiaodan Wang,Jianguang Qin,Dexiang Feng,Liqiao Chen,Fang Qiao,Xianyong Bu

doi:10.3389/fphys.2019.00722

Abstract

Effects of dietary Polychlorinated biphenyl (PCB) exposure and dietary vitamin A supplementation on Chinese mitten crab Eriocheir sinensis were studied with the aim to explain dietary PCB toxicity and toxic alleviation by vitamin A intake in crab. Four diets were used including three experimental diets containing 0, 80000 or 240000 IU/kg vitamin A with each experimental diet containing 10 mg PCB/kg diet, and a control diet (without vitamin A and PCB supplementation) in 56 days feeding trial. Crabs fed the PCB-only diet had significantly lower weight gain than those fed the control diet. No significant difference was observed in crab survival among all groups. Crabs fed the PCB-only diet had a significantly higher malondialdehyde content and antioxidase superoxide dismutase activity in the serum and hepatopancreas, and higher erythromycin N-demethylase and glutathione S-transferase activities in the hepatopancreas than those fed the control diet. However, supplementation of dietary vitamin A decreased the levels of all these parameters. The hepatopancreatic cytochrome P450 2 and 4 (CYP2, CYP4), fatty acid binding proteins 3 and 10 (FABP3, FABP10) and intracellular lipolytic enzyme (IL) Messenger Ribonucleic Acid (mRNA) levels in the PCB-only group were significantly higher than those in the control group, and dietary 240000 IU/kg vitamin A supplementation decreased hepatopancreatic CYP4, FABP3, FABP10 and IL enzyme mRNA level. The crabs fed 80000 IU/kg vitamin A supplementation diet had the highest level of retinoid X receptor mRNA in the hepatopancreas. The structure of the hepatopancreas was damaged and the deposit of lipid droplets decreased with dietary PCB exposure. Both levels of vitamin A supplementation alleviated the damage and increased lipid droplets in the hepatopancreas. Dietary PCB exposure significantly reduced total hemocyte count (THC), and phenoloxidase, acid phosphatase activities in the serum. Post-challenge survival of crab in the experimental PCB-only diet group was low compared with that in the control. Supplementation of 240000 IU/kg vitamin A significantly increased the THC and phenoloxidase activity in the serum and post-challenge survival compared with those in the PCB-only group. This study indicates that dietary vitamin A can improve the antioxidant capacity, immune response, detoxification enzymes activities, energy metabolism and hepatopancreas tissue structure of Chinese mitten crab fed PCB contaminated diets.

Highlights

Polychlorinated biphenyls (PCBs) are a ubiquitous persistent organic pollutant (POP) and is harmful to organisms, while Aroclor 1254 is a commercial PCB manufactured to obtain a specific level of chlorination as a mixture of many PCB congeners
Dietary vitamin A supplementation could alleviate the weight loss induced by persistent organic pollutants in Atlantic salmon, as vitamin A could improve the impaired function of feed utilization due to the loss of intestinal enzyme function, and high energy expenditure for detoxification (Berntssen et al, 2016)
The results showed that dietary 80000 IU/kg vitamin A supplementation could effectively protect hepatopancreas from PCB damage, which may be explained by the use of appropriate amount of vitamin A as an antioxidant in the diet to reduce the level of oxidative stress in E. sinensis

Summary

Introduction

Polychlorinated biphenyls (PCBs) are a ubiquitous persistent organic pollutant (POP) and is harmful to organisms, while Aroclor 1254 is a commercial PCB manufactured to obtain a specific level of chlorination as a mixture of many PCB congeners. The use of PCB has been banned since 1970s, PCBs are still present in the environment in most industrialized countries because they can be transferred, bioaccumulated and biomagnified in the food web (Ulbrich and Stahlmann, 2004). PCBs can cause various adverse effects on many species. With regards to aquatic animals, toxic effects of PCB have been reported in Atlantic killifish (Fundulus heteroclitus, Glazer et al, 2018), Rainbow trout (Oncorhynchus mykiss, Fritsch and Pessah, 2013) and Sea bass (Dicentrarchus labrax, Schnitzler et al, 2011). Farmed crustaceans are at risk of PCB both in the environment and their food organisms (Han et al, 2018). There is a lack of information on the effects of dietary PCB on crustaceans, which may cause a loss of millions of dollars in aquaculture industry

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Results

Conclusion