EFFECT OF VARIOUS CONCENTRATIONS OF LEAD NITRATE ON THE INDUCTION OF MICRONUCLEI IN MOUSE BONE-MARROW

The frequency of micronuclei was evaluated in the bone marrow of mice of either sex administered with 0, 0.625, 1.25, 2.5, 5, 10, 20, 40 and 80 mg/kg b.wt of lead nitrate at 12, 24 and 36 h post-treatment. The frequency of micronucleated polychromatic erythrocytes (MPCE) and micr onucleated normochromatic erythrocytes (MNCE) increased significantly at 12, 24 and 36 h after treatment with lead nitrate compared to non-d rug treated controls. The frequency of micronuclei did not show a dose related increase and the elevation in the frequency of micronuclei wa s fluctuating type. One important observation which emerged from this study was that the male mice were more sensitive to the induction of m icronuclei compared to female mice. This was evidenced by higher frequ encies of MPCE in males than females at all the doses for all the post -treatment time periods. The lead nitrate treatment resulted in a spur t in the erythropoiesis as is evidenced by a significant increase in t he ratios of polychromatic to normochromatic erythrocytes (P/N ratio) compared to non-drug treated controls at 12, 24 and 36 h post-treatmen t. The P/N ratio was significantly higher in females than males at 12 and 24 h post-treatment. (C) 1998 Elsevier Science B.V. All rights res erved.