Adaptive Response Of Splenocyte Apoptosis In Mice Induced By Low Dose Radiation

Objective: To explore the regulative mechanism of apoptosis-associated gene proteins on the adaptive response of splenocyte apoptosis in mice induced by low dose radiation . Methods: Kunming male mice were randomly divided into three groups: sham-irradiated group, challenging dose radiation group(D2 group), low dose radiation + challenging dose radiation group(D1 +D2 group). Having been raised for one week, mice of D1+D2 group were given low dose radiation(D1:25, 50, 75anD100mGy, dose rate: 12.5mGy·min^-1), 6h later mice of D2 group and D1 +D2 group were given challenging dose radiation(D2:1.5Gy, dose rate:287mGy·min^-1). All the mice were sacrificed after 18h. Splenocyte apoptosis and the expression of Caspase-3 were analyzed by flow cytometry. The expressions of Bcl-2 and Bax proteins were detected by immunohistochemistry. Results: 1. Differences of apoptosis rate of splenocyte between groups had notable statistical significance(P<0.01);in sham-irradiated group apoptosis rate was the lowest, while in D2 group apoptosis rate was the highest. Compared with sham-irradiated group the apoptosis rate of D2 group increased significantly, and the difference had notable statistical significance(P<0.01). Compared with D2 group, In D1 + D2 group the apoptosis rate of 25mGy group and 50mGy group decreased, the difference had statistical significance(P<0.05);and the apoptosis rate of 75mGy group decreased significantly, the difference had notable statistical significance (P<0.01);and the apoptosis rate of lOOmGy group decreased, but the difference had no statistical significance(P>0.05). 2. Differences of the expression of Caspase-3 between groups had notable statistical significance(P<0.01);in sham-irradiated group the expression of Caspase-3 was the lowest, while in D2 group the expression of Caspase-3 was the highest. Compared with sham-irradiated group, the expression of Caspase-3 of D2 group increased significantly, the difference had notable statistical significance(P<0.01). Compared with D2 group, In D1 +D2 group the expression of Caspase-3 of 25mGy group decreased, the difference had statistical significance (P<0.05);and the expression of Caspase-3 of 50mGy group and 75mGy group decreased significantly, the difference had notable statistical significance(P<0.01);and the expression of Caspase-3 of lOOmGy group decreased, but the difference had no statistical significance(P>0.05). 3. Differences of the expression of Bcl-2 protein between groups had notable statistical significance(P<0.01). Compared with sham-irradiated group the expression of Bcl-2 protein of D2 group decreased significantly, the difference had notable statistical significance(P<0.01). Compared with D2 group, In D1 + D2 group the expression of Bcl-2 protein of 25mGy group and 50mGy groupincreased, the difference had statistical significance(P<0.05);and the expression of Bcl-2 protein of 75mGy group increased significantly, the difference of which had notable statistical significance(P<0.01);and the expression of Bcl-2 protein of lOOmGy group increased, but the difference had no statistical significance(P>0.05). 4. Differences of the expression of Bax protein between groups had notable statistical significance(P<0.01). Compared with sham-irradiated group the expression of Bax protein of D2 group increased significantly, the difference had notable statistical significance(P<0.01). Compared with D2 group, in Dl + D2 group, the expression of Bax protein of 50mGy group and 75mGy group decreased, the difference had statistical significance(P<0.05);and the expression of Bax protein of 25mGy group and lOOmGy group decreased, but the difference had no statistical significance(P>0.05).Conclusion: The adaptive response of splenocyte apoptosis and the expression of Caspase-3 in mice can be induced by low dose radiation with 25-75mGy. The expression of Bcl-2 protein increased and the expression of Bax protein decreased, which caused the decrease of splenocyte apoptosis.Postgraduate student: Ning Liu (Oncology) Directed by Prof. Hong-Sheng Yu...