Related Experiment Videos
The micronucleus test using peripheral blood reticulocytes from methotrexate-treated mice
Y Kasahara1, A Wakata, Y Nakai
1Safety Research Department, 2nd Bio-Medical Research Laboratories, Teijin Ltd., Tokyo, Japan.
Mutation Research
|February 1, 1992
Summary
Methotrexate (MTX) is a weak inducer of micronuclei in bone marrow cells. However, mouse peripheral blood reticulocytes showed a clear positive response to MTX, indicating higher sensitivity.
Area of Science:
- Toxicology
- Genetics
- Hematology
Background:
- Methotrexate (MTX) is a chemotherapy agent with known genotoxic potential.
- Previous studies indicated MTX as a weak inducer in bone marrow micronucleus tests, with a notable multiple-treatment effect.
- High doses of MTX can severely impact the reticulocyte to erythrocyte ratio, complicating testing.
Purpose of the Study:
- To evaluate the sensitivity of mouse peripheral blood reticulocytes to methotrexate (MTX)-induced micronuclei.
- To compare the genotoxic effects of single versus multiple MTX treatments in peripheral blood.
- To determine optimal conditions for assessing MTX genotoxicity using peripheral blood micronucleus tests.
Main Methods:
- Mice were treated with varying doses of MTX (0-80 mg/kg) and sampled at 0, 24, 48, 72, and 96 hours.
- Micronucleus tests were conducted on peripheral blood reticulocytes.
- Dose-dependent increases in micronucleated reticulocytes (MNRETs) were analyzed.
- Reticulocyte counts were monitored to assess drug toxicity.
Main Results:
- Frequencies of MNRETs increased dose-dependently at 72 hours post-treatment, reaching approximately 1% at higher doses.
- Severe decreases in the reticulocyte to erythrocyte ratio occurred at high MTX doses, hindering some sample analysis.
- Single MTX treatments induced a clear positive response in peripheral blood reticulocytes, suggesting increased sensitivity compared to bone marrow tests.
- The difference between single and multiple treatments was not significant at lower doses (0.5-4.0 mg/kg).
Conclusions:
- Mouse peripheral blood reticulocytes are a more sensitive indicator of MTX-induced genotoxicity than bone marrow cells following single treatments.
- MTX demonstrates clear dose-dependent genotoxic effects in peripheral blood reticulocytes.
- Peripheral blood micronucleus testing offers a sensitive method for evaluating MTX genotoxicity, even with single-dose administration.