RESUMO
The combined effects of mitomycin C (MMC) and thio-tepa (TT) with gamma-ray doses of 5 and 9 Gy on mouse stem cells were studied using the spermatocyte test. Both chemicals induced very low yields of translocations after single treatments. In combined treatments with a dose of 5 Gy, a subadditive effect of MMC and an additive effect of TT were found. Combined with a dose of 9 Gy the compounds potentiated the effect of radiations. Up to now, most of the chemicals tested have shown additive effects when combined with doses of the ascending part of the dose-response curve and potentiating effects when combined with doses of its descending part. This has been considered additional confirmation of the concept that depletion of any kind of spermatogonia is sufficient to modify the genetic response of stem cells. However, the subadditive and additive responses found could be considered evidence that common biological mechanisms can modulate the response to combined treatments of chemicals and ionizing radiations.
Assuntos
Raios gama , Mitomicinas/toxicidade , Radiação Ionizante , Espermatogônias , Espermatozoides , Tiotepa/toxicidade , Translocação Genética , Animais , Relação Dose-Resposta a Droga , Relação Dose-Resposta à Radiação , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Mitomicina , Espermatogônias/efeitos dos fármacos , Espermatogônias/efeitos da radiação , Espermatozoides/efeitos dos fármacos , Espermatozoides/efeitos da radiação , Translocação Genética/efeitos dos fármacos , Translocação Genética/efeitos da radiaçãoRESUMO
The induction of aneuploidy in cultured Chinese hamster cells by propionaldehyde (PA) and chloral hydrate (CH) has been studied. Chinese hamster embryonic diploid (CHED) cells were grown as a monolayer in cover glasses. Treatments were performed with doses of 5 x 10(-4), 1 x 10(-3) and 2 x 10(-3)% of PA for 3 h and doses of 1 x 10(-3), 2 x 10(-3) and 3 x 10(-3)% of CH for 1.5 h. Treatments with 2 x 10(-3)% of acetaldehyde (AA) for the same PA and CH treatments were used as positive controls. Untreated cultures were used as negative controls. PA induced chromosomal aberrations with the three doses employed although in a lesser degree than the positive control. CH induced chromosomal damage only with the two higher doses. No correlation was found between the amount of chromosomal damage induced and the doses of PA or CH employed. Both compounds increased the frequency of aneuploid cells in relation to untreated controls but not in relation to the positive control. However, neither PA nor CH significantly increased the frequencies of polyploid cells. These results indicate that aldehydes and chlorine-replaced aldehydes are strong inducers of aneuploidy despite some differences between PA or CH and AA regarding cytotoxicity and polyploidy induction.