Effect of Chronic Exposure to Pesticide Methomyl on Antioxidant Defense System in Testis of Tilapia (<i>Oreochromis niloticus</i>) and Its Recovery Pattern

• Main Authors: Shunlong Meng, Xi Chen, Chao Song, Limin Fan, Liping Qiu, Yao Zheng, Jiazhang Chen, Pao Xu
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Applied Sciences
• Subjects: tilapia; biomarkers; catalase; glutathione peroxidase; glutathione reductase; glutathione-S-transferase
• Online Access: https://www.mdpi.com/2076-3417/11/8/3332

The chronic effect of environmental methomyl on the antioxidant system in testis of Nile tilapia (<i>Oreochromis niloticus</i>) and its recovery pattern was investigated. Tilapia were exposed to sublethal concentrations of 0.2, 2, 20 and 200 μgL⁻¹ methomyl for 30 days and thereafter moved to methomyl-free water for 18 days. Antioxidant levels in testis, including glutathione peroxidase, catalase, glutathione-S-transferase, glutathione reductase, superoxide dismutase, reduced glutathione, oxidized glutathione were measured every 6 days during the period of exposure, and at 18 days after being transferred to methomyl-free water. The results showed that lower methomyl concentration (0.2 μgL⁻¹) had no effect on the above antioxidants, thus 0.2 μgL⁻¹ could be seen as NOAEL for methomyl to tilapia. However, higher methomyl concentration of 2, 20 and 200 μgL⁻¹ could significantly influence the above antioxidants. Glutathione peroxidase and oxidized glutathione increased significantly. On the contrary, reduced glutathione decreased significantly. Catalase, superoxide dismutase, glutathione reductase, glutathione-S-transferase increased at lower methomyl (2 and 20 μgL⁻¹), but decreased at higher methomyl (200 μgL⁻¹). The recovery test showed that oxidative damage caused by lower methomyl of 2 and 20 μgL⁻¹ was reversible, and oxidative damage caused by higher methomyl of 200 μgL⁻¹ was irreversible within 18 days of recovery period.