褪黑素对镉致鸭大脑皮质毒性损伤的保护作用

为探究褪黑素对镉致鸭大脑皮质毒性损伤的保护作用，本试验将16只20日龄高邮鸭随机分为4组，分别为对照组、褪黑素组、镉组、镉与褪黑素共处理组。对照组鸭自由采食饮水；褪黑素组鸭自由饮用含有0.2 mg·L^-1褪黑素的水；镉组鸭自由采食拌有2 mg·kg^-1氯化镉的饲料；镉与褪黑素共处理组鸭自由饮用含有0.2 mg·L^-1褪黑素水的同时自由采食拌有2 mg·kg^-1氯化镉的饲料。60 d后，剖检并采集鸭大脑皮质。比色法检测大脑皮质中丙二醛（MDA）和总抗氧化能力（T-AOC）的水平，ELISA法检测肿瘤坏死因子（TNF-α）、白介素-1β（IL-1β）的含量，免疫组化染色观察Nrf2核转位，免疫印迹法检测Nrf2、HO-1的蛋白表达。结果显示，与对照组相比，镉组鸭大脑皮质发生明显Nrf2核转位，T-AOC水平极显著降低（P<0.01），MDA、TNF-α、IL-1β含量和Nrf2、HO-1蛋白表达量极显著升高（P<0.01）；与镉组相比，镉与褪黑素共处理组鸭大脑皮质Nrf2核转位减少，T-AOC水平显著升高（P<0.05），MDA、TNF-α、IL-1β含量和Nrf2、HO-1蛋白表达量显著或极显著降低（P<0.05或P<0.01）。综上，褪黑素对镉所致的鸭大脑皮质毒性损伤具有一定的保护作用。

Protective Effect of Melatonin on Toxic Damage Caused by Cadmium in Cerebral Cortex of Duck

In order to investigate the protective effect of melatonin on toxic damage caused by cadmium in cerebral cortex of duck, sixteen GaoYou ducks were randomly allocated into 4 groups:control group, melatonin-treated group, cadmium-treated group, cadmium and melatonin co-treated group. The ducks in the control group were free to eat and drink. The ducks in the melatonin group received drinking water containing 0.2 mg·L^-1 melatonin. The ducks in the cadmium group received feeding mixed with 2 mg·kg^-1 cadmium chloride. The ducks in the cadmium and melatonin co-treated group received drinking water containing 0.2 mg·L^-1 melatonin plus feeding mixed with 2 mg·kg^-1 cadmium chloride. After 60 d, the cerebral cortices of ducks were dissected and collected. The levels of malondialdehyde (MDA) and total antioxidant capacity (T-AOC) in cerebral cortex of duck were measured by colorimetry, the contents of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) were detected by ELISA, the nuclear translocation of Nrf2 was observed by immunohistochemical staining, the protein expression of Nrf2 and HO-1 was detected by Western blot. The results showed that compared with the control group, the Nrf2 nuclear translocation was obvious, the level of T-AOC showed extremely significant decrease (P<0.01), the contents of MDA, TNF-α, IL-1β, the protein expression of Nrf2 and HO-1 showed extremely significant increase (P<0.01) in the cerebral cortex of duck in cadmium-treated group. Compared with the cadmium-treated group, the Nrf2 nuclear translocation was decreased, the level of T-AOC showed significant increase (P<0.05), the contents of MDA, TNF-α, and IL-1β, the protein expression of Nrf2 and HO-1 showed significant or extremely significant decrease (P<0.05 or P<0.01) in the cerebral cortex of duck in cadmium and melatonin co-treated group. The results indicate that melatonin has a protective effect on toxic damage caused by cadmium in cerebral cortex of duck.