Toxicopathology Induced by Microcystins and Nodularin: A Histopathological Review

Abstract

Cyanobacteria are present in all aquatic ecosystems throughout the world. They are able to produce toxic secondary metabolites, and microcystins are those most frequently found. Research has displayed a negative influence of microcystins and closely related nodularin on fish, and various histopathological alterations have been observed in many organs of the exposed fish. The aim of this article is to summarize the present knowledge of the impact of microcystins and nodularin on the histology of fish. The observed negative effects of cyanotoxins indicate that cyanobacteria and their toxins are a relevant medical (due to irritation, acute poisoning, tumor promotion, and carcinogenesis), ecotoxicological, and economic problem that may affect both fish and fish consumers including humans.

Protected Freshwater Ecosystem with Incessant Cyanobacterial Blooming Awaiting a Resolution

“…Structural alterations of the liver observed in this study are similar to those found by other authors after the exposure of fish to cyanotoxins or extracts of cyanobacterial strains and blooms [54][55][56][57][58][59][60]. Most prominent changes were loss of parenchymal structure, rounding of cells, glycogen depletion, vacuolization and pyknosis, all of which were so far reported after exposure of fish to MCs [2]. These alterations, specifically vacuolization and increase of lipid content, were also observed in mammalian livers in reaction to MC [61][62][63].…”

“…In another study from fishponds in Serbia, MC-RR accumulation in muscle tissues was recorded and histopathological changes were noted in liver, kidneys, gills, intestines and muscles of the Cyprinus carpio tissues [41]. Many histological changes in different fish species and tissues after exposure to cyanobacterial bloom or cyanotoxins were presented in a review by Svirčev et al [2].…”

“…Their extensive growth and blooming causes many problems in freshwater ecosystems, including this one. Cyanobacteria can produce cyanotoxins that affect other organisms, including valuable flora and fauna, especially aqueous organisms such as fish [2]. Cyanobacteria also present a threat to humans, such as fishermen, who may be exposed to cyanotoxins through contaminated food, inhalation and direct contact [3,4].…”

Effects of Chronic Exposure to Microcystin-LR on Kidney in Mice

“…Cyanobacterial blooms are an increasing problem worldwide and increasingly attract public attention, since microcystins (MCs) produced by them can cause a series of water quality problems and pose hazards to human and animal health [1][2][3][4][5][6][7]. MCs are a family of cyclic heptapeptide endotoxins.…”

Potential Use of Chemoprotectants against the Toxic Effects of Cyanotoxins: A Review

“…The resulting toxic effects are widely described in the scientific literature. These toxins have been shown to induce histopathological effects [3,4,5], genotoxicity [6,7], neurotoxicity [8,9], developmental toxicity [10,11,12], reproductive toxicity [13,14], etc. In this regard, Buratti et al [15] recently reviewed the most relevant aspects (producing organisms, biosynthesis/genetics and occurrence, toxicological profile) of various cyanotoxins, including MCs and CYN.…”