HYDROQUINONE INCREASES THE FREQUENCY OF MICRONUCLEI IN A DOSE-DEPENDENT MANNER IN MOUSE BONE-MARROW

The frequency of micronuclei (micronucleated polychromatic erythrocyte s, MPCE and micronucleated normochromatic erythrocytes, MNCE) was stud ied at 12, 24 and 36 h post-treatment in the bone marrow of mice treat ed with 0, 0.78, 1.56, 3.125, 6.25, 12.5, 25, 50, 75 and 100 mg/kg bod y wt of hydroquinone (HQ). Treatment of mice with various doses of HQ resulted in a dose dependent increase in the frequency of both MPCE an d MNCE at all the post-treatment time periods. The frequency of MPCE w as significantly higher after administration of 3.125 mg/kg HQ at 24 h post-treatment, except 12 and 36 h, where a significant increase in t he frequency of MPCE was observed only after administration of 6.25 mg /kg drug dose. Similarly, a significant increase in the frequency of M NCE was observed after 12.5 mg/kg HQ treatment at all the post-treatme nt time periods. The dose effect relationship between various HQ doses and MPCE and MNCE induction nias linear and linear quadratic, respect ively al all the post-treatment time periods. The PCE/NCE ratio declin ed in a dose dependent manner at all the post-treatment lime periods a nd this decline was significant when compared to non-drug treated cont rols. The dose effect relationship was linear quadratic at all the pos t-treatment time periods studied. (C) 1997 Elsevier Science Ireland Lt d.