Dose–Response Study of Microcystin Congeners MCLA, MCLR, MCLY, MCRR, and MCYR Administered Orally to Mice

Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA

Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA

Author to whom correspondence should be addressed.

Toxins 2021, 13(2), 86; https://doi.org/10.3390/toxins13020086

Received: 17 December 2020 / Revised: 18 January 2021 / Accepted: 19 January 2021 / Published: 24 January 2021

(This article belongs to the Section Marine and Freshwater Toxins)

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Abstract

Microcystins are common freshwater cyanobacterial toxins that affect liver function. The toxicities of five microcystin congeners (microcystin-LA (MCLA), MCLR, MCLY, MCRR, and MCYR) commonly observed in harmful algal blooms (HABs) were evaluated in BALB/c mice after a single oral administration of doses ranging from those that were no observed adverse effect levels (NOAELs) to lowest observed adverse effect levels (LOAELs). Animals were monitored for changes in behavior and appearance, and euthanized 24 h after dosing. Test endpoints included clinical changes, necropsy observations, and serum indicators of hepatic toxicity and general homeostasis. Doses were 0.5–7 mg/kg MCLA, 0.5–11 mg/kg MCLR, 1–7 mg/kg MCLY, 7–22 mg/kg MCRR, and 3–11 mg/kg MCYR. MCLA at 3 mg/kg elevated liver/body weight ratio and liver score, ALT, AST, and GLDH, indicating hepatic toxicity, reduced serum glucose and highly elevated total serum bilirubin. MCLR and MCLY induced similar effects with LOAELs of 5 mg/kg, although a greater extent and severity of effects were observed in MCLR animals. MCRR exposure at 22 mg/kg was associated with reduced serum glucose. MCYR induced scattered liver effects at 7 mg/kg and reduced serum glucose levels at 5 mg/kg. The results indicate significant differences in congener-induced toxicity after microcystin exposure. View Full-Text

Keywords: harmful algal bloom; cyanobacteria; cyanotoxin; microcystin; hepatic toxicology; oral administration; mouse

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MDPI and ACS Style

Chernoff, N.; Hill, D.; Lang, J.; Schmid, J.; Farthing, A.; Huang, H. Dose–Response Study of Microcystin Congeners MCLA, MCLR, MCLY, MCRR, and MCYR Administered Orally to Mice. Toxins 2021, 13, 86. https://doi.org/10.3390/toxins13020086

AMA Style

Chernoff N, Hill D, Lang J, Schmid J, Farthing A, Huang H. Dose–Response Study of Microcystin Congeners MCLA, MCLR, MCLY, MCRR, and MCYR Administered Orally to Mice. Toxins. 2021; 13(2):86. https://doi.org/10.3390/toxins13020086

Chicago/Turabian Style

Chernoff, Neil, Donna Hill, Johnsie Lang, Judith Schmid, Amy Farthing, and Hwa Huang. 2021. "Dose–Response Study of Microcystin Congeners MCLA, MCLR, MCLY, MCRR, and MCYR Administered Orally to Mice" Toxins 13, no. 2: 86. https://doi.org/10.3390/toxins13020086

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Dose–Response Study of Microcystin Congeners MCLA, MCLR, MCLY, MCRR, and MCYR Administered Orally to Mice

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