Effects of l-cysteine and reduced glutathione on the toxicities of microcystin LR: the effect for acute liver failure and inhibition of protein phosphatase 2A activity

Responses of antioxidant systems in the hepatocytes of common carp (Cyprinus carpio L.) to the toxicity of microcystin-LR

“…Meanwhile, the activity increases of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxide) also reflected that these enzymes played important roles in clearing away excessive ROS and regenerating reduced glutathione. These results were consistent with the previous MC toxicological studies on rate and fish, respectively (Runnear et al, 1987;Takenaka and Otsu, 1999).…”

“…Degradation of MC in water is slow and the toxins often remain in the water supply used by people. There are many reports that Microcystis bloom leads to liver damage in human populations whose water supplies were contaminated by toxic Microcystis (Falconer et al, 1983;Carmichael et al, 1985;Carmichael, 1994;Bell and Codd, 1994 (Runnegar et al, 1987;Takenaka and Otsu, 1999). But little is known about the responses of antioxidant enzymes activities to microcystin-LR in freshwater fish hepatocytes and the relationship between ROS contents and MC shock.…”

In situ studies on physiological and biochemical responses of four fishes with different trophic levels to toxic cyanobacterial blooms in a large Chinese lake

“…Furthermore, supplement with GSH provides animals' higher resistance to MC toxicity. Hermansky et al (1991) revealed that pretreatment of mice with GSH protected them against MC-LR lethality and Takenaka and Otsu (1999) also reported that the mixture of GSH and MC-LR solution weakened acute toxicity of MC-LR than intact MC-LR to mice. Similar results were obtained in Ctenopharngodon idellus, which presented fewer ultrastructural changes by pretreatment with GSH, compared with the fish subjected to MC-LR directly (Zhang et al, 1996).…”

“…MC-LR can conjugate with GSH and ulteriorly be degraded to MCLR-Cys, which can neutralize the electrophilic sites of MC-LR and increase water solubility, consequently reducing the toxicity and enhancing excretion of MC-LR (Kondo et al, 1992). Studies on toxicity of MC-LR on animal hepatocytic antioxidant systems also directly demonstrate that antioxidant systems, mainly GSH, could be relevant indices in explaining the sensitivity of some vertebral species to MC (Takenaka and Otsu, 1999). Furthermore, supplement with GSH provides animals' higher resistance to MC toxicity.…”

Antioxidant response in liver of the phytoplanktivorous bighead carp (Aristichthys nobilis) intraperitoneally-injected with extracted microcystins

“…Furthermore, GSH depletion or formation limits the ability of an organism to detoxify MC-LR or prevent oxidative damage (Wiegand and Pflugmacher 2005). Previous studies on toxicity of MC-LR on animal hepatocytic antioxidant systems also directly demonstrate that antioxidant systems, mainly GSH, could be relevant indices in explaining the sensitivity of some vertebral species to MCs (Takenaka and Otsu 1999). The fact that bighead carp seem less affected by high doses of MCs was reported in previous studies performed in our laboratory in which a cystein conjugate of MC-LR (MCLR-Cys) was detected in most months (July 2004-March 2005 in kidney sample.…”