Effects of acute nitrite stress on immunity function and gill Na+/K+-ATPase activity in Litopenaeus vannamei.

The experiment was conducted to investigate the effects of acute stress with different nitrite concentrations on immunity and gill Na+/K+-ATPase activity of Litopenaeus vannamei. Litopenaeus vannamei with average weight of (1.68±0.23) g were selected. The nitrite concentrations were set as 0 (Control group),0.4, 0.8, 1.6, 3.2 mg/L respectively. The acute stress test lasted for 96 h. Hepatopancreas immune function and gill Na+/K+-ATPase activity were measured at 0, 12, 24, 48, 72, 96 h, respectively. The result showed that the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), acid phosphatase (ACP), alkaline phosphatase (AKP), and lactate dehydrogenase (LDH) in the liver pancreas of Litopenopenus vannamei in stress groups showed an overall trend of increasing first and then decreasing with the extension of stress time. In the 3.2 mg/L group, the activities of SOD, CAT, GSH-Px, and ACP in the liver pancreas of Litopenopenus vannamei all dropped to the level of the control group after 96 hours of stress. The activity of LDH dropped to the level of the control group after 24 hours of stress and then continued to decrease significantly below the level of the control group (P<0.05). Except for the 0.4 mg/L group, where the content of malondialdehyde (MDA) in the hiver pancreas of Litopenopenus vannamei dropped to the level of the control group after 96 hours of stress, the MDA content in all other groups was significantly higher than that of the control group during the 96 hours of stress (P<0.05). Within 96 hours of stress, the activity of Na+/K+-ATPase in the gills of Litopenopenus vannamei in the 0.4 mg/L group continued to rise; the activity of Na+/K+-ATPase in the gills of Litopenopenus vannamei in the 0.8 to 3.2 mg/L groups showed a trend of initial activation followed by inhibition with the extension of stress time, and in the 3.2 mg/L group, it dropped to the level of the control group after 96 hours of stress. The study shows that the immune function and gill Na+/K+-ATPase activity of Litopenaeus vannamei were significantly affected under acute nitrite stress of 0.4 to 3.2 mg/L. When the salinity is (24.0±1.0) parts per thousand, it is necessary to control the nitrite content within 0.4 mg/L during the healthy aquaculture process of the Litopenaeus vannamei. [ABSTRACT FROM AUTHOR]