title: Relation between rate of cell proliferation and formation of micronuclei after combined treatment with X-rays and caffeine.
abstract: We studied the effects of caffeine (2 mM), X-rays (1 Gy) and the combination of both agents on cell proliferation and formation of micronuclei in the early stages of preimplantation mouse embryos in vitro. Two-cell embryos were exposed to the agents shortly before division to the 4-cell stage. Proliferation and micronucleus production was monitored every 2 h in the 4- and 8-cell stages. A rather peculiar pattern of micronucleus formation after radiation exposure alone was observed for 8-cell embryos: those embryos that were the first to enter the 8-cell stage showed two to three times higher numbers of micronuclei per cell when compared with those embryos that entered the 8-cell stage some hours later. Studies of the kinetics of cell proliferation and of micronucleus formation in 4- and 8-cell embryos and exposure to caffeine revealed that this result could be explained by two factors: a slight asynchrony in the developmental stage at the time of exposure and the length of the interval being available for repair processes. When caffeine was present, a third factor had to be taken into consideration: direct inhibition of repair by caffeine.
authors.affiliation: Institut für Medizinische Strahlenbiologie, Universitätsklinikum Essen, Germany.
authors.forename: W U
authors.initials: WU
authors.lastname: Müller
authors.forename: C
authors.initials: C
authors.lastname: Kasper
authors.forename: C
authors.initials: C
authors.lastname: Streffer
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000528:radiation effects*; D002110:Caffeine / Q000633:toxicity*; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D051379:Mice; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects / Q000528:radiation effects*; D015162:Micronucleus Tests; D009924:Organ Culture Techniques; D011247:Pregnancy; D013997:Time Factors; D014965:X-Rays
chemical_list: D002110:Caffeine