Effects Of Low Dose Pre-irradiation On The Toxicity Of Clophosphamide

Objective: To study the effects as well as the possible mechanisms of low dose γ-ray pre-irradiation on hepatic damage, DNA damage of peripheral lymphocytes and genetic material damage caused by high dosage of cyclophosphamide(CTX). Methods: Kunming strain male mice were randomly divided into five groups: control group, sham-irradiated group, low dose irradiation group(LDR group), cyclophosphamide chemotherapy group(CTX group) and low dose irradiation combined with chemotherapy group(LDR+CTX group). Having being raised for one week, all the mice were implanted subcutaneously with S180 cells in the left groin (control group excluded). On day 8 and 11, mice of LDR and LDR+CTX group were given 75mGy whole-body y -irradiation, 30h later mice of CTX and LDR+CTX group were injected i.p. 3.0 mg cyclophosphamice. All the mice were sacrificed on day 13. DNA damage of the peripheral lymphocytes were analyzed using single cell gel electrophoresis(SCGE); ALT activity, total protein(TP) and albumin(ALB) of the plasma were analyzed using automatic biochemistry analyzer; M.DA content, SOD and GSH-PX activity of the hepatic homogenate were analyzed using chromometry; genetic material damage was analyzed using micronucleus frequency(MNF) of polychromatoerythrocytes(PCE) in bone marrow. Results: 1. Differences of MDA contents, SOD and GSH-PX activity of hepatic homogenate between 5 groups had notable statistical significance(P<0.01); in control group MDA content was the lowest, SOD and GSH-PX activity were the highest, while in CTX group MDA content was the highest, SOD and GSH-PX activity were the lowest; compared with CTX group MDA content decreased significantly(P<0.01) and SOD and GSH-PX activity increased significantly(P<0.05) in LDR+CTX group. 2. Differences of ALT activity of plasma between 5 groups had no statistical significance (F=1.262, P>0.05). Differences of TP and ALB of plasma between 5 groups had statistical significance(F=12.879, 6.336 respective, P<0.01); TP and ALB in control group were higher than other groups and compared with sham-irradiated group, TP and ALB in LDR group elevated significantly(P<0.05). 3. Differences of DNA damage of peripheral lymphocytes had notable statistical significance (F=6.383, P<0.01); DNA damage in control group is the lightest, while DNA damage in CTX group is the severest; compared with CTX group, DNA damage in LDR+CTX group was much lighter(P<0.05). 4. MNF...