盐度胁迫对大鳞鲃抗氧化酶和血清皮质醇的影响

为阐明盐度胁迫对大鳞鲃(Luciobarbus capito)肝、肾和鳃组织抗氧化系统及血清皮质醇的影响,本研究设置4个NaCl盐度组(3、6、9和12 g/L)和1个淡水对照组,检测分析了不同盐度胁迫下曝露3、6、12、24、48、96 h和7 d大鳞鲃肝、肾和鳃组织中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、谷胱甘肽过氧化物酶(GSH-Px)的活性和丙二醛(MDA)含量的变化,以及血清中皮质醇浓度的变化。结果显示,在相同盐度胁迫下,大鳞鲃的肝、肾和鳃组织中ACP、AKP、GSH-Px抗氧化酶的活力、MDA含量以及血清皮质醇含量随胁迫时间的延长均呈先上升后下降、随后趋于稳定的变化趋势,在胁迫开始24 h内各指标达到峰值,并在48 h开始逐渐趋于平稳;胁迫初期,相同曝露时间,大鳞鲃的肝、肾和鳃组织中3种抗氧化酶活力、MDA含量及血清皮质醇含量均与盐度呈显著正相关性。大鳞鲃在盐度胁迫过程中,ACP、AKP活力和MDA含量在肾组织的范围分别为1.42~2.15 U/g prot、1.01~1.87金氏单位/g prot和13.05~57.27 nmol/mg prot;肝组织中分别为1.27~1.96 U/g prot、0.31~0.86金氏单位/g prot和17.02~55.98 nmol/mg prot;鳃组织则为0.98~1.96 U/g prot、0.13~0.84金氏单位/g prot和8.33~53.93 nmol/mg prot,肾组织中ACP、AKP活力和MDA含量均高于肝、鳃组织;而GSH-Px的活力在肝、肾和鳃组织的范围分别为44.41~114.77、16.52~67.59和9.07~48.00活力单位,肝组织中GSH-Px活力显著高于肾和鳃组织。此外,血清皮质醇在盐度胁迫过程中的含量变化范围为197.00~355.50 ng/L。综上所述,在12 g/L的高盐胁迫下大鳞鲃通过自身调节,各项指标仍可恢复正常,表明其对盐度环境有较强的适应能力。

Effects of salinity stress on antioxidant enzymes and serum cortisol in Luciobarbus capito

This study examined the effects of salinity stress on the antioxidant system of the liver, kidney, and gill and the serum cortisol levels of Luciobarbus capito. Four NaCl salinity groups (3, 6, 9, and 12 g/L) and a freshwater control group were set up in this experiment. Further, we detected the activities of acid phosphatase (ACP), alkaline phosphatase (AKP), glutathione peroxidase (GSH-Px), and the content of malondialdehyde (MDA) in the liver, kidney, and gill, as well as the serum cortisol level at seven salinity exposure time points (3 h, 6 h, 12 h, 24 h, 48 h, 96 h, and 7 d). The results indicated that under salinity stress, the antioxidant enzyme activity, MDA content in the liver, kidney, and gill, and serum cortisol levels were increased and then decreased as the stress exposure time increased, after which they tended to be stable. They reached the maximum value within 24 h after exposure of L. capito to salinity and reduced within 48 h and stabilized within 96 h~7 d. Antioxidant enzyme activities, MDA content in the liver, kidney, and gill; and serum cortisol levels were proportional to salinity. Further, ACP, AKP activity, and MDA content were higher in the kidney than in the liver and gill under salinity stress. ACP activity was approximately 1.27~1.96 U/g prot in the liver, 1.42~2.15 U/g prot in the kidney, and 0.98~1.96 U/g prot in the gill; AKP activity in these three tissues was approximately 0.31~0.86, 1.01~1.87, and 0.13~0.84 king unit/g prot, respectively, and MDA content was 17.02~55.98 nmol/mg prot, 13.05~57.27 nmol/mg prot, and 8.33~53.93 nmol/mg prot, respectively. However, GSH-Px activity in the three tissues was 44.41~114.77, 16.52~67.59, and 9.07~48.00 active unit, respectively, indicating that it was significantly higher in the liver than in the kidney and gill. In addition, serum cortisol level was 197.00~355.50 ng/L under salinity stress. Overall, L. capito can become normal through self-regulation under 12 g/L salinity, indicating that they have strong adaptability to saline environment.