Effects Of Exogenous Metallothionein On Lymphocytes Apoptosis Of Dairy Cow Under Heat Stress

To research the effects of exogenous MT on lymphocyte apoptosis of dairy cow cultured in vitro under heat stress, the splenic lymphocyte of dairy cow was divided into4groups, with the final concentration of MT0μg/ml (control group),70μg/ml (group Ⅰ),140μg/ml (group Ⅱ),210μg/ml (group Ⅲ). The cells of each groups were cultured in cell incubator (37℃,5%CO2).After20h, the cells of each groups were put in water bath pot(43℃) for1h,and they were cultured again in cell incubator (37℃,5%CO2) for3h.Last,the various of indexes were tested. The results as follow:1) The results showed that MT added in cell culture medium could relieve the damage of dairy cow lymphocyte under heat stress, but the effect decreased with increasing of the MT concentration by the observation of morphology and AO/EB staining.2) The apoptotic index of control group and the group Ⅱ were no significant difference, the apoptotic index of the group Ⅲ was significantly higher than another groups(P<0.01), the apoptotic index of control group and the group Ⅱ were significantly higher than trial I(P<0.01) from the results on lymphocyte apoptotic index of dairy cow. Relative cell survival rate of the control group was the lowest, the group Ⅰ was significantly higher than another groups(P<0.01), with the increasing of exogenous MT, the relative cell survival rate was trend of reduction by the methods of MTT and trypan blue. It was illustrated that MT can improve lymphocyte survival rate of dairy cow and restrain lymphocyte apoptosis of dairy cow.3) The antioxidant index of lymphocyte were tested. The trial groups’ activity of CAT, SOD, GSH-Px were higher than the control group’s and the content of MDA was lower than the control group’s. The results explained MT improved antioxidation of lymphocyte.4) The genes related to cell apoptosis in lymphocyte were tested. The results as follow:the relative transcript level of Bax in the group I to III were significantly lower than the control growp(P<0.01). the relative transcript level of Bcl-2in the group I to III were significantly higher than the control group(P<0.01). the relative transcript level of p50in the group I to III were significantly lower than the control group(P<0.01). It was indicated that MT could regulate expressing of gene which related to lymphocyte apoptosis.In conclusion, exogenous MT could decrease lymphocyte mortality rate, improve lymphocyte inoxidizability and restraine lymphocyte apoptosis. The final concentration of MT70μg/ml had best effect.