Selective cytotoxicity of microcystins LR, LW and LF in rat astrocytes

• Published in: Toxicology letters 2017-01, Vol.265, p.1-8
• Main Authors: Bulc Rozman, Klara, Jurič, Damijana Mojca, Šuput, Dušan
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Apoptosis - drug effects; Astrocytes; Astrocytes - drug effects; Astrocytes - metabolism; Astrocytes - ultrastructure; Cell Survival - drug effects; Cells, Cultured; Cerebral Cortex - cytology; Cytoskeleton; Cytotoxicity; Dose-Response Relationship, Drug; Glial Fibrillary Acidic Protein - metabolism; Microcystin; Microcystins - toxicity; Oatp; Organic Anion Transporters - metabolism; Primary Cell Culture; Rats; Rats, Wistar
• ISSN: 0378-4274; 1879-3169
• DOI: 10.1016/j.toxlet.2016.11.008

•MC-LF and MC-LW, but not MC-LR, are toxic to astrocytes.•MC-LW and MC-LF induce apoptosis of rat cortical astrocytes.•MC-LW and MC-LF intoxication induce GFAP, actin and tubulin network degradation.•Rat cortical astrocytes express Oatp1a4, Oatp1c1 and Oatp1a5, but not Oatp1b2. Microcystins (MCs) comprise a group of cyanobacterial toxins with hepatotoxic, nephrotoxic and, possibly, neurotoxic activity in mammals. In order to understand the development of their neurotoxicity we investigated the toxic effects of MC variants, MC-LR, MC-LW and MC-LF, in astrocytes that play a central role in maintaining brain homeostasis. 24h exposure of cultured rat cortical astrocytes to MCs revealed dose-dependent toxicity of MC-LF and MC-LW, but not of MC-LR, observed by significant reduction in cell number, declined viability monitored by MTT test and an increased percentage of apoptotic cells, confirmed by Annexin-V labelling. The cultured astrocytes expressed organic anion-transporting polypeptides (Oatp) Oatp1a4, Oatp1c1 and Oatp1a5, but not Oatp1b2. Intracellular localisation of MC-LF and MC-LW, proven by anti-Adda primary antibody, demonstrated transport of tested MCs into cultured astrocytes. Acute MC-LW and MC-LF intoxication induced cytoskeletal disruption as seen by the degradation of glial fibrillary acid protein (GFAP), actin and the tubulin network. In this in vitro study, MC-LF and MC-LW, but not MC-LR, are shown to cause the dysfunction of astrocytic homeostatic capabilities, already at low concentrations, suggesting that astrocyte atrophy, with loss of function, could be expected in the brain response to the toxic insult.