Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

Abstract

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.

Simultaneous use of erythropoietin and prior bleeding enhances the sensitivity of the peripheral blood micronucleus assay

“…Splenectomy has been used in various experimental studies to diminish splenic removal of micronucleated cells (17)(18)(19)(20). However, splenectomy causes loss of hematopoietic activity and depletion of ERTs reserves (21). Owing to these drawbacks, effort has been made to strategies that stimulate the formation and release of ERTs, such as recombinant erythropoietin (EPO) (22,23), prior bleeding (PrB) (3,21,(24)(25)(26), hypoxia (27), cyclic adenosine monophosphate (28), protein deprivation (29) and hypothermia (30) (Figure 1).…”

Assessment of the mutagenic potential of para‐chloroaniline and aniline in the liver, spleen, and bone marrow of Big Blue® rats with micronuclei analysis in peripheral blood

“…An increase in extramedullary hematopoiesis would decrease the burden of red blood cell generation by bone marrow and thus the likelihood for micronucleus formation. This is supported by evidence which suggests that accelerated erythroblast maturation reduces the efficiency of DNA repair and leads to an increase in micronucleated erythrocytes (Suzuki et al, 1989) and by data indicating that increased hemopoiesis leads to an increase in micronuclei (Steinheider et al, 1985;Tweats et al, 2007). Therefore, a decrease in the burden of bone marrow to generate reticulocytes would be expected to decrease the level of MnRETs.…”

Comparative Activity of Human Carcinogens and NTP Rodent Carcinogens in the Mouse Bone Marrow Micronucleus Assay: An Integrative Approach to Genetic Toxicity Data Assessment

“…Other factors such as hyperthermia (22,23) and erythropoietin-induced erythropoiesis (24,25) have also been associated with increases in MPE frequencies in rodents. Further, methemoglobinemia induced in rodents by exposure to aniline (26) and spleen damage associated by their exposure to phenylhydrazine (27) .MIIS -9 ior, urinary incontinence, etc., must be used to indicate possible stress-related activity in the MN assay. Evaluation of genetic toxicity tests has been in an analytical phase for the past 20 years.…”