DETECTION OF RODENT LIVER CARCINOGEN GENOTOXICITY BY THE ALKALINE SINGLE-CELL GEL-ELECTROPHORESIS (COMET) ASSAY IN MULTIPLE MOUSE ORGANS (LIVER, LUNG, SPLEEN, KIDNEY, AND BONE-MARROW)

We have recently designed a simple method for applying the alkaline si ngle-cell gel electrophoresis (SCG) assay to mouse organs. With this m ethod, each organ is minced, suspended in chilled homogenizing buffer containing NaCl and Na,EDTA, gently homogenized using a Potter-type ho mogenizer set in ice, and then centrifuged nuclei are used for the alk aline SCG assay. In the present study, we used the method to assess th e genotoxicity of 8 rodent hepatic carcinogens in 5 mouse organs (live r, lung, kidney, spleen, and bone marrow). The carcinogens we studied were p-aminoazobenzene, auramine, 2,4-diaminotoluene, p-dichlorobenzen e, ethylene thiourea (ETU), styrene-7,8-oxide, phenobarbital sodium, a nd benzene-1,2,3,4,5,6-hexachloride (BHC); except for p-aminoazobenzen e, they do not induce micronuclei in mouse bone marrow cells. Mice wer e sacrificed 3 and 24 h after the administration of each carcinogen. p -Aminoazobenzene, ETU, and styrene-7,8-oxide induced alkaline labile D NA lesions in all of the organs studied. Auramine, 2,4-diaminotoluene, p-dichlorobenzene, and phenobarbital sodium also produced lesions, bu t their effect was greatest in the liver. BHC, which is not genotoxic in in vitro tests, did not show any effects. We suggest that it may be possible to use the alkaline SCG assay to detect in vivo activity of chemicals whose genotoxicity is not expressed in bone marrow cells. (C ) 1997 Elsevier Science B.V.