Effect of acute ammonia toxicity on inflammation, oxidative stress and apoptosis in head kidney macrophage of Pelteobagrus fulvidraco and the alleviation of curcumin.

Ammonia is one of the most major pollutant and stress factors of aquaculture systems, and has seriously endangered fish health. However, few studies have been performed on mechanisms of the detrimental impact of ammonia stress and mitigation in fish. A study was carried out to investigate the response of genes involved in inflammation, antioxidation, polarization and apoptosis in head kidney macrophages to acute ammonia toxicity, and the alleviation effect of curcumin. The cells were divided into six groups, as follows: The control group composed of untreated macrophages (CON), the experimental groups, consisting of macrophages treated with 0.23 mg L-1 ammonia (AM), 45 μmol L-1 curcumin (CUR), 0.23 mg L-1 ammonia and 5 μmol L-1 curcumin (5A), 0.23 mg L-1 ammonia and 25 μmol L-1 curcumin (25A), 0.23 mg L-1 ammonia and 45 μmol L-1 curcumin (45A). The cells were pretreated with different concentrations of curcumin for 1 h and then incubated with ammonia for 24 h. The results showed that ammonia poisoning could increase ROS levels, up-regulate the expression of antioxidant enzymes (SOD and GPx), inflammatory cytokines (IL-1, IL-6 and TNF-α) and inflammatory mediators (NF-κB p65 and COX-2), decrease cell viability, down-regulate the expression of M2 marker (Arg-1) and anti-apoptosis (Bcl-2), but curcumin could alleviate the adverse effect of ammonia toxicity. Overall, these results have important implications for understanding of the mechanism of ammonia toxicity and the mitigating effect of curcumin in fish.