Protective role of dietary N‐acetylcysteine on the oxidative stress induced by cylindrospermopsin in tilapia (Oreochromis niloticus)

Abstract

Cylindrospermopsin (CYN) is a toxin produced by various cyanobacteria species. Fish can be exposed to this cyanotoxin in their natural environments and in aquaculture ponds, and toxic effects can be derived. The present study investigated the effects of dietary N-acetylcysteine (NAC) on the oxidative stress induced by pure CYN and CYN from lyophilized cells of Aphanizomenon ovalisporum in tilapia (Oreochromis niloticus). Fish were pretreated with 0, 22, and 45 mg NAC/fish/d for a week, and on day seven, they received a single dose of 200 µg/kg CYN and were killed after 24 h. Oxidative biomarkers evaluated included lipid peroxidation, protein oxidation, glutathione (GSH)/oxidized glutathione (GSSG) ratio, activity of the enzyme γ-glutamylcysteine synthetase, and activity and gene expression of glutathione-S-transferase and glutathione peroxidase. Results showed that CYN induced oxidative stress as evidenced by the increase of lipid peroxidation and protein oxidation, the decrease in GSH/GSSG, and the alteration of the enzymatic activities assayed. Moreover, exposure to cyanobacterial cells containing CYN induced higher toxic effects in comparison to pure CYN. N-acetylcysteine supplementation was effective at reducing the toxicity induced by CYN, particularly at the highest dose employed, with a recovery of some of the biomarkers assayed to basal levels. Therefore, NAC can be considered a useful chemoprotectant that reduces hepatic and renal oxidative stress in the prophylaxis and treatment of CYN-related intoxication in fish.