Hepatic and renal toxicity of the blue-green algae (cyanobacterium): cylindrospermosis raciborskii in male swiss albino mice

Abstract

When administered to mice, either orally or intraperitoneally, extracts of the cyanobacterium Cylindrospermopsis raciborskii strain AWT 205 induced dose-dependent liver and kidney damage. Liver damage was generally centrilobular, becoming more severe and generalized as the dose increased. Damaged hepatocytes were characterized by increased cellular vacuolation, intercellular spaces, and darker nuclear and cytoplasmic staining. Kidney damage was characterized by a reduction in the number of erythrocytes in the glomerulus and an increase in the space around the glomerulus, increased diameter of the tubule lumina, proximal tubule epithelial necrosis, and the presence of proteinaceous material in the distal tubules. Transmission electron microscopy of the same tissue revealed epithelial cell necrosis in the proximal tubules, suggesting the material accumulating in the distal tubules was in part cell debris from this necrosis. The nature, location, and time course of histological damage were similar for oral and intraperitoneal administration, with maximum damage being observed 2-3 days after treatment. The LD50 (24 h) for intraperitoneally administered Cylindrospermopsis preparations ranged from 50 to 110 mg dry weight of lysed cells per kilogram, whereas the LD50 (7 days) ranged between 20 and 65 mg/kg depending upon the batch examined. In contrast, oral administration of 1400 mg/kg, while inducing clear histological damage, was not fatal to any of the animals used in the study. The extent of comparative severity of damage to the liver and kidneys caused by different batches of Cylindrospermopsis of similar cylindrospermopsin content varied considerably, implying the presence of more than one toxin.