Influence of Microcystin-LR on the activity of membrane enzymes in rat intestinal mucosa

CAMEÁN. Influence of Microcystin-LR on the activity of membrane enzymes in rat intestinal mucosa. J. Physiol. Biochem., 59 (4), 293-300, 2003. The objective of the present study was to evaluate the effects of microcystin-LR (MCLR) on the activity of membrane enzymes from intestinal mucosa. In addition, serum chemistry and peroxidative status of both serum and intestinal homogenate were evaluated after treatment with MCLR. Wistar rats were treated with intraperi-toneal injection of either 100 µg pure MCLR/Kg body weight or saline solution. A significant increase in liver weight and altered serum enzyme activities were found in MCLR-treated rats, indicating damage to the liver in these rats, as previously sug-gested. A higher specific activity of sucrase (1.5-fold) was observed after the admin-istration of MCLR, whereas other intestinal apical membrane enzymes, such as lac-tase, maltase and alkaline phosphatase were not modified by the treatment. The spe-cific activities of acid phosphatase and succinate dehydrogenase, markers for lysoso-mal and mitochondrial membranes, respectively, were also increased (32 % and 60%, respectively) in treated rats. The analysis of lipid peroxidation showed that the per-oxidative status was increased in both serum and intestinal mucosa from MCLR-treated rats, reflecting an excess production of oxygen free radicals induced by this cyanobacterial toxin. In conclusion, this study shows that acute exposure to MCLR affects the intestinal physiology by modifying the intestinal peroxidation status as well as the activity of membrane enzymes