Maternal repeated oral exposure to microcystin‐LR affects neurobehaviors in developing rats

Abstract

Microcystins are toxic peptides secreted by certain water blooms of toxic cyanobacteria. The most widely studied microcystin is microcystin-LR (MC-LR), which exhibits hepatotoxicity and neurotoxicity. However, limited information is available regarding the effects on offspring following maternal exposure. The present study was conducted to observe the effects of progestational exposure to MC-LR on postnatal development in rats. Female Sprague-Dawley rats (28 d old) were randomly divided into a control group and 3 treatment groups (1.0 µg MC-LR/kg body wt, 5.0 µg MC-LR/kg body wt, and 20.0 µg MC-LR/kg body wt), with 7 rats per group. The MC-LR was administered through gavage once every 48 h for 8 wk. Pure water was used as control. Each female rat was mated with an unexposed adult male rat. Motor development, behavioral development, and learning ability of pups were detected using surface righting reflex, negative geotaxis, and cliff avoidance tests on postnatal day 7. Open-field and Morris water maze tests were performed on postnatal day 28 and day 60. The levels of lipid peroxidation products and antioxidant indices in the rat hippocampus were also detected. Pups from the MC-LR-treated groups had significantly lower scores than controls in the cliff avoidance test (p < 0.05). Cognitive impairment, malondialdehyde level, and total superoxide dismutase activity significantly increased in MC-LR-exposed pups compared with controls (p < 0.05). Therefore, the present study reveals that maternal exposure to MC-LR has adverse effects on neurodevelopment in rat offspring.

A review of reproductive toxicity of microcystins

“…Recently, several studies have confirmed the trans-generational toxicity of MCs in zebrafish [143] and rats [142,144]. When adult zebrafish were continuously exposed to MC-LR (1, 5, and 20 g/L) for 30 days, the growth (body weight and body length) of the F1 generation at 60 days post fertilization (dpf) was significantly inhibited even though the embryos and larvae were free of MC exposure [143].…”

“…Qiao et al [85] reported that MC-LR exposure exerts diverse reproductive toxicity in zebrafish, with females exhibiting more sensitivity than males. However, Li et al [142] demonstrated that male offspring are more susceptible to maternal exposure of MC-LR on memory function than females. Therefore, female reproductive effects of MCs should be strengthened in future studies.…”

“…Female SD rats were intragastrically administered with 1, 5, and 20 g MC-LR/kg bw once every 48 h for 8 weeks [142]. Each female rat was mated with an unexposed adult male rat.…”

Cyanobacterial Toxins of the Laurentian Great Lakes, their Toxicological Effects, and Numerical Limits in Drinking Water

“…Li et al [158] MCs does not consider this study in calculating the guideline value for MCs in drinking water.…”

“…Indeed, direct injection of MC to rat hippocampus at femtogram levels has been shown to affect learning and memory [153,154,158]. MCs have also been shown to alter fish behavior and learning as well as increase acetylcholinesterase activity in fish brain [152].…”