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

Sequential ultrastructural and biochemical changes induced in vivo by the hepatotoxic microcystins in liver of the phytoplanktivorous silver carp Hypophthalmichthys molitrix

“…injection of MC-LR (10-400 μg/kg). Li et al (2003) observed a similar decrease in common carp hepatocytes when exposed to 10 μg MC-LR/L. However, such a significant decrease of GSH level was not observed in silver carp.…”

“…An increase in GST activity was found in the hepatopancreas of Chasmagnathus granulatus after MCs exposure representing a greater detoxification capacity through conjugation of MCs with glutathione (GSH) (Pinho et al, 2003). The depletion of the hepatic GSH after exposure to MC-LR was observed in the studies with goldfish (Xu et al, 1998) and common carp (Li et al, 2003). On the other hand, several recent studies have shown that exposure to MCs or to microcystic cyanobacterial extract results in transient elevation of intracellular GSH content, both in vitro (Ding et al, 2000) and in vivo (Gehringer et al, 2004).…”

Hepatic Histopathological Characteristics and Antioxidant Response of Phytoplanktivorous Silver Carp Intraperitoneally Injected with Extracted Microcystins

“…In the present study, the significantly increased SOD activity indirectly verified that oxidative stress occurred in the liver of silver carp, indicating that toxin-induced oxidative stress activates antioxidant enzymes to eliminate ROS and protects cells from lesion. It was reported that CAT, SOD, and GPX activities as well as ROS levels are increased in hepatocytes of common carp exposed to MC-LR [4] . It has also been found that commercial eel food containing cyanobacterial cells can significantly increase the activity of CAT, SOD, and GPX in the liver of loach 28 days after oral exposure to 10.0 μg MC-RReq./kg/day [9] .…”

“…One of the well-studied toxic mechanisms of MCs is their ability to inhibit protein phosphatases 1 and 2A, inducing hyperphosphorylation of cytosolic and cytoskeletal proteins, which leads to disruption of the hepatocyte cytoskeleton in animals and fish [3][4] . At present, there is also evidence that oxidative damage is involved in the development of MCs toxicity in mammals [5][6] .…”

“…At present, there is also evidence that oxidative damage is involved in the development of MCs toxicity in mammals [5][6] . To date, however, the effects of MCs on antioxidant systems of fish have only been observed in Danio rerio embryos [7] , isolated hepatocytes of common carp (Cyprinus carpio) [4] , liver of goldfish (Carassius auratus) and loach (Misgurnus mizolepis) either injected intraperitoneally (i.p.) with MC-LR or exposed to cyanobacterial blooms [8][9] .…”