Effects of Avermectin Exposure on Oxidative Stress and Histological Structure of Hepatopancreas in Eriocheir sinensis
An acute semi-static toxic test was carried out to study the modulation of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and malondialdehyde content (MDA), which was the main product of lipid peroxidation, at 12, 24, 48 and 96 h in hepatopancreas when Eriocheir sinensis was exposed to different aver-mectin concentrations including 1.6, 8.0 and 16.0μg·L-1 . Histological structure and color variations of hepatopan-creas were observed on day 60 in test group, blank group and vehicle group, respectively. Three different avermec-tin concentration groups were test groups, and blank group and vehicle group were control groups. Results were as follows:(1) The three indicators had no significant differences at different time in both vehicle group and blank group, and vehicle group also had no obvious differences from blank group. SOD and CAT activities at the concen-tration of 1.6 μg·L-1 also had no significant differences from control groups (P>0.05). The activities of SOD and CAT showed the similar variation in 8.0μg·L-1 group, and they were induced continuously throughout the experi-ment. SOD activity increased extremely significantly compared with blank group (P<0.01) after 24 h, and CAT ac-tivity was extremely significantly higher than blank group after 48 h (P<0.01). SOD and CAT activities were all in-duced between 12 h and 24 h at the concentration of 16.0μg·L-1, but SOD activity decreased significantly after 48 h (P<0.05). At 96 h, the activity of SOD was extremely lower than blank group. However, CAT activity was still extremely significantly higher than blank group (P<0.01). MDA levels of test groups gradually increased along with the increase of stress time of avermectin, and the oxidative stress indicators of low avermectin concentration group varied less than that of high concentration group. (2) Histological structure and color of hepatopancreas were affected at different degrees at different avermectin concentrations for 60 days. The hepatopancreas of E.sinensis of control groups was normal, but hepatopancreas of test groups changed from orange red to light yellow, yellowish-white or stark white. The percentage of white hepatopancreas of 16.0 μg·L-1, 8.0 μg·L-1 and 1.6 μg·L-1 groups was 66.6%, 57.1% and 25.0%, respectively. Histopathological analysis revealed the different pathological lesions of hepatopancreas of different colors. The number of B cells of hepatopancreas was decreased, and some hepatic cells were swelling and had cavity in hepatopancreas of light yellow. When the color of hepatopancreas changed to yellowish-white, the degree of deterioration of hepatopancreas aggravated. The number and volume of vacuoles in-creased, some contents were present in the vacuoles, and nucleus were pyknotic. In the white hepatopancreas, the basement membrane became thicker, some hepatic cells were crushing and many cell debris appeared in the lumen, many vacuoles existed between the basement membrane and epithelial cells, and the physiological function of hepa-topancreas was impaired. The results indicated that avermectin could result in oxidative stress and tissue damage in hepatopancreas of E. sinensis, and the oxidative stress effects and the degree of pathological lesions had a dose-effect relationship with avermectin.
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维普
