Microcystin-LR Induces Alterations in Heart Muscle

Milutinović, Aleksandra; Zorc-Pleskovič, R.; Petrovič, D.; Zorc, M.; Šuput, D.

doi:10.14712/fb2006052040116

Fol. Biol. 2006, 52, 116-118

https://doi.org/10.14712/fb2006052040116

Microcystin-LR Induces Alterations in Heart Muscle

Aleksandra Milutinović¹, R. Zorc-Pleskovič¹, D. Petrovič¹, M. Zorc¹, D. Šuput²

¹Institute of Histology and Embryology, Medical School, Medical Faculty of Ljubljana, University of Ljubljana, Ljubljana, Slovenia
²Institute of Pathophysiology, Medical School, Medical Faculty of Ljubljana, University of Ljubljana, Ljubljana, Slovenia

Received July 2006
Accepted September 2006

MC-LR belongs to a family of cyanobacterial toxins. MC-LR acts as serine-threonine phosphatase-1 and -2A inhibitor. Chronic intoxication with low doses of this toxin promotes liver tumour formation and induces kidney injury. The aim of the study was to evaluate whether chronic exposure to relatively low doses of MC-LR has toxic effects on hearts of treated animals. Male adult Wistar rats were treated every second day for 8 months with MC-LR (10 µg/kg i. p., N = 5). Control groups were treated either with a vehicle (ethanol and methanol 4 : 1 v/v; N = 5) or with physiologic saline (N = 4). We found that MC-LR could induce enlargement of cardiomyocytes (MC-LR = 20.984 µm ± 1.351, vehicle=17.454 µm ± 0.518, saline = 15.996 µm ± 1.430), loss of cell cross-striations, lower myofibril volume fraction (MC-LR = 0.3657 mm³/mm³ ± 0.0337, vehicle=0.4716 mm³/mm³ ± 0.0086, saline = 0.4793 mm³/mm³ ± 0.0101), fibrosis (MC-LR = 0.0747 mm³/mm³ ± 0.01288, vehicle = 0.0275 mm³/mm³ ± 0.0076, saline = 0.0309 mm³/mm³ ± 0.0074) and mononuclear infiltration in the interstitial tissue. The TUNEL staining of the heart sections of rats in all groups showed no apoptotic cells. We may conclude that long-term exposure to relatively low doses of MC-LR represents a considerable risk of injury of the heart.