维生素C和酸应激对中华鳖幼鳖血清补体C3和C4含量的影响

为研究维生素C对中华鳖(Pelodiscus sinensis)血清补体C3和C4的影响及其在酸应激条件下的变化，我们设置了6个实验组，饵料中维生素C的添加量依次为0、250、500、2500、5000和10000mg／kg，喂食4周后取其血清，用透射比浊法测定酸应激前后中华鳖血清补体C3和C4的含量。结果表明，维生素C添加量为250mg／kg时，血清补体C3的含量与对照组间没有明显不同；维生素C添加量为500、2500、5000和10000mg／kg的4组，血清补体C3的含量明显高于对照组和维生素C添加量为250mg／kg组；维生素C添加量为500mg／kg的一组，血清补体CA含量明显高于其它5组；维生素C添加量为250mg／kg组明显高于10000mg／kg组。酸应激后，补体C3的含量没有明显下降，将维生素C添加量为0、250和500mg／kg的三组并为一组处理，则应激后有明显下降。维生素C添加量为0、250和500mg／kg的3组，血清补体CA的含量在酸应激后明显下降，而维生素C添加量为2500、5000和10000mg／kg的3组，应激后血清补体C4没有明显变化。维生素C和酸应激对中华鳖血清补体C3和CA含量的影响没有交互作用。这说明，维生素C在一定剂量范围内，能提高中华鳖血清补体C3和CA的水平，酸应激能导致其含量降低，而高剂量的维生素C对其下降有颉颃作用动物学报49(6)：769～774，2003]。

Effects of vitamin C and acid-stress on serum complement C3 and C4 level in juvenile soft-shelled turtles (Pelodiscus sinensis)

This study was conducted to investigated the effects of dietary vitamin C on serum complement C3 and C4 in stressed and unstressed juvenile soft shelled turtle. The turtles were fed with vitamin C supplementation at dosages of 0, 250, 500, 2 500 , 5 000 and 10 000 mg/kg diets, respectively for 4 weeks. Blood was collected from turtles and levels of serum complement C3 and C4 analyzed by the transmission colorimetric method. Levels of serum complement C3 between the control group and the group supplemented vitamin C at 250 mg/kg diet showed no significant difference. The levels of serum complement C3 in the four groups supplemented with vitamin C at 500, 2 500, 5 000 and 10 000 mg/kg diet were significantly higher compared with the control group. The level of serum complement C4 in the group supplemented vitamin C at 500 mg/kg diet was distinctly higher than the other five groups, and in the group supplemented with vitamin C at 250 mg/kg diet was higher than 10 000 mg/kg group. After acid stress, the complement C3 levels had no significant difference compared with the ones of before stress, while there was a significant decrease after stress when the three groups supplemented vitamin C at 0, 250 and 500 mg/kg diet were put together to analyze. The levels of serum complement C4 in the three groups supplemented with vitamin C at 0, 250 and 500 mg/kg diet decreased significantly, while the other groups at 2 500 , 5 000 and 10 000 mg/kg diet had no significant difference after acid stress. No interaction effects of vitamin C and acid stress on the levels of serum complement C3 and C4 were observed. These results suggest that vitamin C seems to have an upper and lower threshold for improving levels of serum complement C3 and C4 in turtles, and acid stress decreases the their levels, while the high dosage vitamin C can prevent this decline.