The influence of vinblastine treatment on the formation of radiation-induced micronuclei in mouse bone marrow.

The combined effects of vinblastine sulphate (VBL) and gamma radiation treatments on the induction of micronuclei in polychromatic erythrocytes (MPCE) and normochromatic erythrocytes (MNCE) and changes in polychromatic/normochromatic erythrocyte ratio (P/N ratio) in mouse bone marrow, were studied. Compared to double distilled water (DDW) injected controls, 0.05 mg/kg b.wt. of vinblastine alone significantly increased the frequency of MPCE and MNCE. When VBL was administered before exposure to various doses of gamma radiation the frequency of micronuclei (MPCE and MNCE) increased with the increasing radiation dose up to a dose of 4 Gy, but this increase levelled off at 3 to 4 Gy irradiation. The frequency of MPCE was found to be significantly lower at 3 and 4 Gy radiation when compared to the DDW+irradiated group. A significant dose dependent decline in the P/N ratio was observed in the DDW+irradiated group. VBL treatment before irradiation resulted in a more significant decline in the P/N ratio than that of DDW+irradiated group. The formation of micronuclei (MPCE and MNCE) increased from 8 h post-exposure and continued to increase up to 28 h. There was a sharp decline in the frequency of micronuclei (MPCE and MNCE) at 32 h post-irradiation, in both DDW + 1 Gy irradiated and VBL + 1 Gy irradiated groups; then it declined gradually up to 72 h post-exposure without restoration to normal level. The P/N ratio declined with time in all three groups (VBL alone, DDW+irradiation, and VBL+irradiation) without restoration to normal level up to 72 h post-treatment, except in the DDW+irradiated group, where it was normal.