Microcystin-LR induces alterations in heart muscle
Milutinović, A.; Zorc-Pleskovic, R.; Petrovic, D.; Zorc, M.; Suput, D.
Folia Biologica 52(4): 116-118
2006
ISSN/ISBN: 0015-5500 PMID: 17116283 Document Number: 599522
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 mu g/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 mu m d = 1.351, vehicle = 17.454 mu m +/- 0.518, saline = 15.996 mu m +/- 1.430), loss of cell cross-striations, lower myofibril volume fraction (MC-LR 0.3657 mm(3)/mm(3) 0.0337, vehicle = 0.4716 mm(3)/mm(3) +/- 0.0086, saline = 0.4793 mm(3)/mm(3) +/- 0.0101), fibrosis (MC-LR = 0.0747 mm(3)/mm(3) +/- 0.01288, vehicle = 0.0275 mm(3)/mm(3) +/- 0.0076, saline = 0.0309 mm(3)/mm(3) +/- 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.