Cylindrospermopsin effects on cell viability and redox milieu of Neotropical fish Hoplias malabaricus hepatocytes

Abstract

Cylindrospermopsin (CYN) is a cyanotoxin that is cytotoxic to a wide variety of cells, particularly to the hepatocytes. In this study, the toxic effects of purified CYN were investigated in primary cultured hepatocytes of Neotropical fish Hoplias malabaricus. After isolation, attachment, and recovery for 72 h, the cells were exposed for 72 h to 0, 0.1, 1.0, 10, and 100 μg l of CYN. Then, cell viability and a set of oxidative stress biomarker responses were determined. Catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione S-transferase activities were not affected by exposure to CYN. Concentration-dependent decrease of glutathione reductase activity occurred for most CYN-exposed groups, whereas non-protein thiol content increased only for the highest CYN concentration. Lipid peroxidation, protein carbonylation, and DNA damage levels were not altered, but reactive oxygen species levels increased in the cells exposed to the highest concentration of CYN. Cell viability decreased in all the groups exposed to CYN. Thus, CYN may cause a slight change in redox balance, but it is not the main cause of cell death in H. malabaricus hepatocytes.

In Vitro Toxicological Assessment of Cylindrospermopsin: A Review

“…In human HUVEC cells, on the other hand, they found a concentration-dependent increase (from 0.375 to 1.5 µg/mL CYN) [ 37 ], and in human intestinal cells, the increase was only evident at the highest concentration tested (2.5 µg/mL) [ 36 ]. Other authors who found a significant increase were Fernández et al [ 39 ], in the rat hepatic cell line Clone 9, and Silva et al [ 63 ], in Hoplias malabaricus hepatocytes. In any case, it has been suggested that the GSH reduction does not contribute significantly to CYN acute toxicity in vivo [ 64 ].…”

“…Other authors suggest that oxidative stress may be better defined as a disruption of redox signaling and control [ 58 ]. Table 4 [ 9 , 22 , 24 , 26 , 34 , 35 , 36 , 37 , 38 , 39 , 41 , 59 , 60 , 61 , 62 , 63 ] shows the in vitro studies available in the scientific literature dealing with oxidative stress induced by CYN.…”

“…In the first group, the enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), among others, play an important role. SOD, CAT, GPx, Glutathione S-transferase (GST), and glucose-6-phosphate dehydrogenase (G6PDH) were not altered in Hoplias malabaricus hepatocytes that were exposed to up to 100 μg/L CYN for 72 h [ 63 ]. Different results were obtained by Poniedziałek et al (2015) in human lymphocytes.…”

“…These differences could be due to the different experimental models (primary cells or cell lines of various origins), CYN concentrations, or exposure periods that were employed. Moreover, given that CYN is also an environmental contaminant, it is noteworthy that few reports are available with fish in vitro models [ 34 , 35 , 61 , 63 ].…”

“…With regard to in vitro studies, various assays have been performed ( Table 5 ) [ 26 , 27 , 28 , 35 , 53 , 60 , 63 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ], mainly in mammalian systems, which demonstrated the pro-genotoxic activity of CYN.…”