RESUMO
INTRODUCTION: Increase in the instability of cellular genome with an increasing age is the result of an accumulation of cellular damage and mutations. This instability which might be observed as chromosome damage or chromosome losses can be measured by the micronucleus technique. AIM: The aim of this study was to investigate the effect of aging and oxidative stress induced by non-toxic levels of H2O2 on micronuclei induction and their relationship to cell proliferation in human peripheral blood lymphocytes. MATERIALS AND METHODS: Healthy volunteers with different ages were choosen. Spontaneous and H2O2 induced micronuclei frequencies were measured in peripheral blood lymphocytes of 30 volunteers by the micronucleus method. RESULTS: Spontaneous micronuclei frequencies increased first then started to decrease after 50 years of age. This biphasic response was significantly higher than micronucleus (MN) frequencies induced by H2O2 (P < 0.05), which followed the similar shape of response to increasing ages with lower frequencies. Proliferative capacity of cells either treated with H2O2 or not did not differ with an increasing age giving similar responses. CONCLUSION: These results indicate biphasic character of chromosome damage; first increase and decrease after 50 years with an increasing age. But this change pattern was not correlated with the steady state of proliferation capacity of cells through an increasing age. Decreases in H2O2-induced MN frequencies compared to spontaneous MN frequencies may be inducing an apoptosis by H2O2 treatment leading to underscoring damaged cells.