| Microcystis bloom occurs frequently in freshwater all over the world in recent years due to theeutrophication of water body, and it has been a serious aquatic environmental pollution issue in many countries.The bloom can decrease the quality of drinking water and increase the risk of toxicity to aquatic organisms andeven humans because of the highly toxic microcystins(MCs)produced mainly by Microcystis aeruginosa. TheMC target organ was reported to be animal liver, and a long-term MC-exposure of humans could induce hepatitisand promote hepatoma. In view of these, WHO has recommended the guideline value of MC content to be1μg/L in drinking water for people. There have been many reports on the hepatic toxicity and embryonic toxicityof MC while few reports are available now regarding MC's reproductive toxicity. These years, some researchersfound that MC could accumulate in testis of some aquatic animals during the period of Microcystis bloom andMC had testicular toxicity in rat, confirming the reproductive toxicity of MC in rodents.In the present study, acute and testicular toxicity of Microcystis cell extracts and the crude product ofmicrocystins extracted from the cyanobacteria on mice were determined by intraperitoneal injection. Results ofthe acute toxicity tests indicated that the24h-LD50of the cell extracts and crude microcystins for mice were30μg/kg and41μg/kg, respectively. Moreover, subchronic exposure of the cell extracts and crude microcystinsdisturbed the spermatogenesis and maturation of mice sperm, caused structural alteration of convolutedseminiferous tubule, and promoted activities of the testicular marker enzymes, i.e. ACP and LDA, but failed toinduce sperm malformation. In addition, MC-exposure also increased the mRNA expression of Cyp450scc,Claudin1, and Occludin in mice testes at the early stages of treatment(1-7d)and inhibited their expression after7d of MC-exposure. In conclusion, MCs have reproductive toxicity on mice according to our study. |
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