Effect Of Manganese On DNA Damage And Cell Apoptosis In Mice And The Antagonism Of Zinc

Objective: To research the influence of manganese and the antagonistic action of zinc on DNA damage and apoptosis in brain and liver cells in mice. Methods: Kunming mice were randomly divided into seven groups , control group and other six groups were injected intraperitoneally manganese chloride(MnCl2) with three different doses and zinc through the drinking water. Six weeks later, the rates of DNA migration were measured with single cell gel electrophoresis(SCGE). The frequencies of micronucleatde poly chromatic erythrocytes (PCE)in the born marrow were measured with micronucleus test. Apoptosis in brain and liver cells in mice were detected with DNA agarose gel electrophoresis and TUNEL. Result: The results showed that (1) the rates of DNA migration increased significantly with the increase of manganese, higher than the control group(P<0.01). There were remarkably difference between low, medium and high dose group and they have dose- response relationship. After add zinc, the rates of DNA migration lower than the groups which exposed to manganese(P<0.01). (2) the frequency of PCE in the born marrow increased significantly with the increase of manganese, medium and high dose group higher than the control group(P<0. 01). There were remarkably difference between low, medium and high dose group. After add zinc , the low dose Mn+Zn group decreased near to the normal; medium and high dose Mn+Zn group decreased, still higher than the control group, but have difference with the groups which exposed to manganese. (3) DNA"Ladder" fragmentation of apoptosis hepatocytes were shown on agarose gel electrophoresis in the groups of high dose and high dose Mn+Zn. While many TUNEL positive hepatocytes were found in those groups. Conclusion: Manganese can cause cell DNA damage and apoptosis in brain and liver cells. However ,those effects can be antagonized by zinc.