饲料维生素C对急性降温后花鲈免疫、抗氧化及抗应激的影响

Effects of dietary vitamin C on the immune, antioxidant capacity and stress tolerance of spotted seabass (Lateolabrax maculatus) after acute cooling

中文关键词: 花鲈  维生素C  急性降温  抗应激

英文关键词: Lateolabrax maculatus  Vitamin C  Acute cooling stress  Stress tolerance

中文摘要:

      为研究饲料维生素C(Vc)对急性降温后花鲈(Lateolabrax maculatus)免疫、抗氧化及抗应激的影响，以含有不同水平Vc (6.85、46.90、88.24、167.43、329.21和658.69 mg/kg)的饲料饲养花鲈56 d后，进行急性降温(从33℃水体转入27℃水体)处理24 h和48 h。结果显示，降温24 h和48 h时，各组血清补体3(C3)水平高于0 h，而补体4(C4)水平低于0 h。饲料Vc在6.85~167.43 mg/kg时，血清免疫球蛋白M(IgM)水平随降温时间的增加，在24 h和48 h显著高于0 h (P<0.05)；当饲料Vc含量高于167.43 mg/kg时，各时间点IgM差异不显著。血清溶菌酶(LZM)活性在降温48 h后显著低于降温前(P<0.05)，而各Vc添加组显著高于对照组(P<0.05)。肝脏丙二醛(MDA)含量在降温后显著高于降温前，但在降温后随着饲料Vc水平的升高而显著降低(P<0.05)。肝脏总超氧化物歧化酶(T-SOD)含量随降温时间的增加，先增加后降低。在各时间点，花鲈肝脏谷胱甘肽(GSH)含量都随着饲料Vc水平的升高而升高。当饲料Vc为6.85 mg/kg时，肝脏血红素氧合酶(HO-1)活性在降温后显著高于降温前(P<0.05)；当饲料Vc为88.24~167.43 mg/kg时，肝脏HO-1活性在降温后显著低于降温前(P<0.05)。花鲈血清热休克蛋白(HSP70)水平在降温后显著高于降温前(P<0.05)，而当降温时间达到48 h时，各Vc添加组HSP70含量显著低于对照组。研究表明，饲料中适量的Vc (46.90~167.43 mg/kg)能提高花鲈肝脏的抗氧化能力，减轻脂质过氧化水平，缓解花鲈急性降温引起的应激反应。

英文摘要:

      The purpose of this study was to investigate the effects of dietary vitamin C on the immunity, antioxidant capacity, and stress tolerance of juvenile Lateolabrax maculatus under acute cooling stress. An 8-week feeding trial was conducted with experimental diets containing 6.85, 46.90, 88.24, 167.43, 329.21, and 658.69 mg/kg vitamin C (Vc). Some fish were then exposed to acute cooling stress for 24 h and 48 h (transferred from 33℃ water to 27℃ water). The results showed that the serum levels of Complement 3 (C3) in each group after cooling were higher than before cooling, while the levels of serum Complement 4 (C4) showed the opposite pattern. When dietary Vc was 6.85~167.43 mg/kg, the levels of serum immunoglobulin M (IgM) at 24 h and 48 h were higher than at 0 h (P<0.05). However, there were no differences among the treatments with higher dietary Vc supplementation (329.21~658.69 mg/kg; P>0.05). After cute cooling for 48 h, the levels of serum lysozyme (LZM) were lower than at 0 h, but the Vc-supplemented groups were higher than the control group (P<0.05). The concentration of hepatic malondialdehyde (MDA) were higher in all groups after cooling stress than before cooling stress, but decreased with increasing levels of dietary Vc (P<0.05). Total superoxide dismutase (T-SOD) activity initially increased but then decreased with greater cooling time, and the glutathione (GSH) content increased with increasing dietary Vc supplementation. Heme oxygenase-1 (HO-1) activity in the 6.85 mg/kg Vc group was higher after cooling stress, but the groups supplemented with 88.24 to 167.43 mg/kg Vc had lower activities after cooling (P<0.05). The levels of heat shock proteins (HSP70) were higher before acute cooling, and when cooled for 48 h, HSP70 levels in the Vc -supplemented groups were lower than the control group (P<0.05). These results suggest that dietary Vc supplementation (46.90~167.43 mg/kg) may improve antioxidant capacity, reduce lipid peroxidation, and enhance the resistance to acute cooling in L. maculatus.