Dietary N-Acetylcysteine (NAC) prevents histopathological changes in tilapias (Oreochromis niloticus) exposed to a microcystin-producing cyanobacterial water bloom

The present study investigates the effects of the oral administration of N-acetylcysteine (NAC), a glutathione (GSH) precursor, on the pathological changes induced by Microcystic cyanobacterial cells containing microcystins (MCs) in an important aquaculture fish species, tilapia (Oreochromis niloticus). Fish were exposed to a single oral dose of 120 μg MC-LR/fish and sacrificed in 24 h. Pathological lesions in the hepatic and renal tissues, intestines, heart, and gills were investigated in the absence and presence of 20.0, 44.0 and 96.8 mg NAC/fish/day. Results showed a protective role of NAC mainly at the median dose used (44.0 mg NAC/fish/day), which reduced tissue lesions probably due to its antioxidant activity. The highest dose, however, induced toxic effects even in fish exposed only to NAC. Therefore, it can be considered a useful chemoprotectant in the prophylaxis and prevention of MC-related intoxications in fish. However, particular attention must be paid to its application dose because of its pathological activity, which was shown by the present study to start from 96.8 mg NAC/fish/day.