ACRYLAMIDE-INDUCED CHROMOSOMAL DAMAGE IN MALE-MOUSE GERM-CELLS DETECTED BY CYTOGENETIC ANALYSIS OF ONE-CELL ZYGOTES

Within a project coordinated by the Commission of the European Communi ties for the detection of germ cell mutagens, the cytogenetic analysis of first-cleavage metaphases was carried out to detect chromosomal da mage induced by acrylamide (AA) in meiotic and postmeiotic stages of m ouse spermatogenesis. Male mice were intraperitoneally injected with s ingle acute doses of 75 or 125 mg/kg or treated with five daily inject ions of 50 mg/kg and mated either 7 or 28 days after the end of treatm ent. Chromosomal aberrations were scored in C-banded metaphases prepar ed from one-cell zygotes by a mass harvest technique. AA treatment of late spermatids-spermatozoa resulted in significant increases of struc tural aberrations at all doses tested. The data could be fitted to a c urvilinear regression and a doubling dose of 23 mg/kg was calculated. The large majority of observed aberrations were of the chromosome type , including dicentrics, rings and translocations, in agreement with a mechanism of chromosomal damage mediated through the alkylation of DNA -associated protamines. Even though the frequency of aberrations 28 da ys after treatment was not significantly higher than the control value , the presence of multiple rearrangements in two cells suggested that AA might also have a minor effect on spermatocytes. The results of the cytogenetic analysis of first cleavage metaphases agreed well both qu alitatively and quantitatively with the outcome of dominant lethal and heritable translocation assays. AA-induced cytotoxicity was monitored by flow cytometric DNA content analysis of testicular cells. By this method, a dose-dependent depletion of mature spermatids after treatmen t of spermatogonia and a toxic effect upon primary spermatocytes were detected.