Micronucleus test using cultured new born rat astrocytes

Abstract

Micronuclei is induced in cytoplasm as a consequence of the formation of chromosomal fragments or remaining chromosomes during cell division by the cause of clastogens or spindle poisons, and is used as an indicator of genotoxicity screening tests. There are few short-term genotoxicity screening tests using brain cells. We attempted to establish a new in vitro micronucleus test (MN test) system by use of central nervous system cells. Primary cultured astrocytes were prepared from newborn male Sprague-Dawley (SD) rats. In growth curve of astrocytes, doubling time was determined to be 31 h. In time study, the highest frequency of micronuclei was observed at 48 h, 72 h and 6 h-exposure-66 h-recovery by vincristine (VCR), mitomycin C (MMC) without metabolic activation system and cyclophosphamide (CPM) with metabolic activation system, respectively. Dose-response relationships between micronucleus frequency and concentrations of MMC, VCR and CPM were observed, respectively. It is suggested that the in vitro MN test using new born rat-astrocytes could be used as a screening test of environmental and occupational genotoxic chemicals in the central nervous system cells.