Subchronic Microcystin-LR Exposure Increased Hepatic Apoptosis and Induced Compensatory Mechanisms in Mice

NOELIA LEZCANO; DANIELA SEDÁN; IGNACIO LUCOTTI; LEDA GIANNUZZI; LETICIA VITTONE; DARÍO ANDRINOLO; CECILIA MUNDIÑA -WEILENMANN

JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY

JOHN WILEY & SONS INC

Lugar: New York; Año: 2012 vol. 26 p. 131 - 138

1095-6670

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