Microcystin Contamination In Aquatic Environment Of The Three Gorges Reservoir And Antagonism Study On MC-LR Induced Toxicity

Microcystin(MC) is characterized as monocyclic heptapeptides with over 80 different isoforms identified, which is mainly produced by some cyanobacteria species and has strongly hepatotoxic effects on animals and human beings, among which, microcystin-LR with potent hepatotoxicity is well studied. Liver is the principal target organ of microcystin toxicity. MC is potent hepatotoxin due to its inhibition of several serine/threonine protein phosphatases including PP1 and PP2A, it is a highly irritant tumor promoter. MC, together with hepatitis virus and aflatoxin, has been regarded as three environmental risk fators which promote liver cancer in south China by some researchers based on risk evaluation methods.After the establishment of the Three Gorges dam in the Yangtze River, the flow velocity of the river will slow down greatly and the self-purification ability will decline. The occurrence of eutrophication in the reservoir will be highly probable. It seemed urgent for us to monitor the MC contamination both in municipal water supply system of Chongqing city and aquatic environment of the Three Gorges reservoir. Additionally, we are eager to find out some effective approaches which can prevent and protect human being from MC hazards. The first part of our study was to investigate the microcystin contamination status and related physicochemical and biological parameters in water body of the municipal water supply system in Chongqing city and the Three Gorges reservoir. Our study aimed to evaluate the MC contamination status in the Three Gorges reservoir so as to offer theoretic reference to reasonable drinking water utilization. Meanwhile, considering the diverse functional properties of tea polyphenols and green tea including anti-oxidative, anti-mutagenic and anti-carcinogenic effects and the scarcity of reports on chemoprotectants against microcystin induced toxicity, the second part of our study was to evaluate the potential benefits of pretreatment with tea polyphenols and green tea administration prior to MC-LR injection and also to elucidate the mechanisms of tea polyphenols antagonism effects.