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 erythrocy tes (MPCE) and normochromatic erythrocytes (MNCE) and changes in polyc hromatic/normochromatic erythrocyte ratio (P/N ratio) in mouse bone ma rrow, were studied. Compared to double distilled water (DDW) injected controls, 0.05 mg/kg b.wt. of vinblastine alone significantly increase d the frequency of MPCE and MNCE. When VBL was administered before exp osure 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 significan t dose dependent decline in the P/N ratio was observed in the DDW + ir radiated group. VBL treatment before irradiation resulted in a more si gnificant 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 decl ine in the frequency of micronuclei (MPCE and MNCE) at 32 h post-irrad iation, in both DDW + 1 Gy irradiated and VBL + 1 Gy irradiated groups ; then it declined gradually up to 72 h post-exposure without restorat ion to normal level. The P/N ratio declined with time in all three gro ups (VBL alone, DDW + irradiation, and VBL + irradiation) without rest oration to normal level up to 72 h post-treatment, except in the DDW irradiated group, where it was normal.