Long-term hypoxia stress-induced oxidative stress, cell apoptosis, and immune response in the intestine of Pelteobagrus vachelli.

Abstract

Hypoxia is a common phenomenon in aquaculture. With the dissolved oxygen (DO) 3.75 ± 0.25mg O2 /L for hypoxia group and 7.25 ± 0.25mg O2 /L for control group for 30, 60, and 90days, long-term hypoxia stress was used to investigate the oxidative stress, apoptosis, and immunity in the intestine of Pelteobagrus vachelli. According to the results of measurement of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and catalase (CAT) activities and malondialdehyde (MDA) content, the oxidative stress ability of the intestine was activated at 30days and impaired at 60 and 90days. The upregulation of Bcl-2-associated x (Bax); downregulation of B cell lymphoma-2 (Bcl-2); increased activities of caspase-3, caspase-9, and Na+-K+-ATPase; decreased activities of succinate dehydrogenase (SDH); and the release of cytochrome c (Cyt-c) in mitochondria revealed that hypoxia induced the apoptosis. Moreover, heat shock protein 70 (HSP 70), heat shock protein 90 (HSP 90), immunoglobulin M (IgM), and C-lysozyme (C-LZM) were activated to inhibit apoptosis, but the immunoregulatory function might be damaged at 60 and 90days. This study provides a theoretical foundation for understanding the mechanisms of hypoxia stress and aquaculture management of P. vachelli.