Potential Endocrine Disruption of Cyanobacterial Toxins, Microcystins and Cylindrospermopsin: A Review

Abstract

Microcystins (MCs) and cylindrospermopsin (CYN), although classified as hepatotoxins and cytotoxins, respectively, have been shown to also induce toxic effects in many other systems and organs. Among them, their potential endocrine disruption (ED) activity has been scarcely investigated. Considering the increasing relevance of ED on humans, mammals, and aquatic organisms, this work aimed to review the state-of-the-art regarding the toxic effects of MCs and CYN at this level. It has been evidenced that MCs have been more extensively investigated than CYN. Reported results are contradictory, with the presence or absence of effects, but experimental conditions also vary to a great extent. In general, both toxins have shown ED activity mediated by very different mechanisms, such as estrogenic responses via a binding estrogen receptor (ER), pathological changes in several organs and cells (testis, ovarian cells), and a decreased gonad-somatic index. Moreover, toxic effects mediated by reactive oxygen species (ROS), changes in transcriptional responses on several endocrine axes and steroidogenesis-related genes, and changes in hormone levels have also been reported. Further research is required in a risk assessment frame because official protocols for assessment of endocrine disrupters have not been used. Moreover, the use of advanced techniques would aid in deciphering cyanotoxins dose-response relationships in relation to their ED potential.

Freshwater Cyanobacterial Toxins, Cyanopeptides and Neurodegenerative Diseases

“…Thus, MC-LR can induce apoptosis and atrophy of gonadotropin-releasing hormone (GnRH) neurons in rats’ hypothalamus [ 284 , 285 ]. Although the molecular mechanism of MC-LR- induced apoptosis remains elusive, growing evidence supports that MCs and other cyanobacterial toxins, such as cylindrospermopsin, act as endocrine disruptors [ 286 , 287 ]. Recently, Shi and co-authors [ 288 ] demonstrated that acutely administrated MC-LR induces pathological changes in rat’s hypothalamus and pituitary gland and alters the transcription of genes involved in hormone biosynthesis.…”

A Sensitive Fluorescence Polarization Immunoassay for the Rapid Detection of Okadaic Acid in Environmental Waters

“…The pollution of environmental waters with aquatic toxins destroys marine and freshwater ecosystems, reduces the productivity of mariculture farms, damages tourism and recreational systems, and reduces biodiversity [ 2 ]. The consumption of contaminated fish and mollusks poses a great hazard to human health, causing intestinal disorders, and amnesic, hepatotoxic, and neuroparalytic symptoms, while chronic intake may provoke oncological diseases [ 6 , 7 , 8 , 9 ].…”

A Direct Analysis of β-N-methylamino-l-alanine Enantiomers and Isomers and Its Application to Cyanobacteria and Marine Mollusks

“…With fossils dating back up to 3.6 billion years [3][4][5][6][7], these organisms are considered to have had a large influence on the evolution of our planet, such as through the generation of the oxygen atmosphere and the Great Oxidation Event [8][9][10][11]. More recently, cyanobacteria have also been shown to produce a large number of toxic compounds [12][13][14][15], including peptides, alkaloids and components of the cell wall, such as microcystins [16][17][18][19][20], cylindrospermopsins [21][22][23][24][25][26], anatoxin-a [27][28][29][30], anatoxin-a(S) (guanitoxin; [31][32][33][34][35][36][37]), saxitoxins [38][39][40][41][42], and LPS [43][44][45] as examples. With regard to human health, exposure to these toxins can occur through a wide range of exposure routes such as drinking water [46,47], the consumption of seafood in...…”