Subchronic microcystin-LR exposure increased hepatic apoptosis and induced compensatory mechanisms in mice |
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Authors: | Lezcano Noelia Sedán Daniela Lucotti Ignacio Giannuzzi Leda Vittone Leticia Andrinolo Darío Mundiña-Weilenmann Cecilia |
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Institution: | Centro de Investigaciones Cardiovasculares, CCT-La Plata CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 1900 La Plata, Argentina. |
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Abstract: | Acute lethal cytotoxicity of microcystin-LR (MC-LR), a toxin produced by fresh-water cyanobacteria, has been attributed to protein phosphatases type 1 and type 2A (PP1/PP2A) inhibition and reactive oxygen species (ROS) generation. However, the effects and molecular mechanisms of prolonged, sublethal MC-LR exposure are less known. We studied mice intraperitonealy injected with saline or 25 μg MC-LR/kg for 28 days (every 2 days). MC-LR induced apoptosis in liver and not in kidneys or heart of treated animals. Liver also showed decreased α-tubulin levels (45.56% ± 7.65% of controls) and activation of p38-MAPK and CaMKII pathways (137.93% ± 11.64% and 419.35% ± 67.83% of the control group, respectively). PP1/PP2A activity decreased from 1.82 ± 0.23 (controls) to 0.91 ± 0.98 mU/mg (MC-LR-treated mice); however, no difference in total Ser/Thr phosphatase activity was found between both the groups. The results demonstrated that apoptosis and cytoskeleton disruption contributed to the hepatic cytotoxic effects of subchronic MC-LR administration. These effects occurred in association with sustained activation of signaling cascades and development of compensatory mechanisms to maintain total Ser/Thr phosphatase activity. |
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Keywords: | Microcystin Prolonged Exposure Apoptosis Signaling Pathways Phosphatase Activity |
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