EFFECTS OF CADMIUM ON APOPTOSIS OF CARDIOMYOCYTE IN THE FRESHWATER CRAB SINOPOTAMON YANGTSEKIENSE
镉诱导长江华溪蟹(Sinopotamon yangtsekiense)心肌细胞凋亡的研究

The effects of cadmium(Cd) on cardiomyocyte apoptosis in the freshwater crab Sinopotamon yangtsekiense were investigated by acute systemic toxicity testing methods.To verify if apoptosis is one of the cardiomyocyte death pathways upon Cd administration,crabs were exposed to different concentrations of Cd(0,7.25,14.50,29.00,58.00 and 116.00 mg/L) for 1,3,5 and 7 days.The results of hematoxylin and eosin(H.E.) staining assays showed that there were no obvious alterations in cardiac histology of crabs in low concentrations and short-term exposure groups.With increasing Cd concentrations and exposure time,histological abnormalities appeared including vacuolar and vitreous degeneration,and infiltration of inflammatory cells.Apoptosis-like cells were observed,but rare in 7d exposure groups.Besides,the characteristic apoptotic morphologic changes and "ladder" pattern weren’t observed by fluorescence microscopy with Hoechst 33258 staining and agarose gel electrophoresis.Flow cytometry assay indicated that the percentage of apoptotic cells were increased with the increasing of exposure time and concentrations of Cd compared with control,but there was no significant difference.Moreover,the activity of Caspase-3 was not affected by Cd treatment after 7 days exposure.However,these findings suggest that apoptosis wasn’t induced by Cd in cardiomyocyte in the present study.While previous studies in our lab showed that Cd induced apoptosis in the hepatopancreas and testis cells of crabs after 2 days and 7 days exposure.In crab cardiomyocyte,the lack of Cd-induced apoptosis may be attributed to different Cd accumulation amount in the three tissues.