Effects of a combination of X-rays and caffeine on preimplantation mouse embryos in vitro

Abstract

The influence of a combination of caffeine (0.1 mM, 1 mM, or 2 mM) and X-rays (0.24 Gy, 0.94 Gy, or 1.88 Gy) on preimplantation mouse embryos in vitro was studied under different conditions. The agents were applied either singly or in combination. The embryos were irradiated in the G2-phase of the two-cell stage (28 h p. c. or 32 h p. c.) either 1 h after or immediately before application of caffeine. Caffeine was present during the whole incubation period (until 144 h p. c.). The effects on the microscopic visible development (formation of blastocysts 96 h p. c., hatching of blastocysts 144 h p. c.) and on the cell numbers of embryos at different times (48 h p. c., 56 h p. c., 96 h p. c., 144 h p. c.) were determined. We found conditions under which caffeine markedly enhanced radiation risk, i.e., under which the combination effect exceeded the sum of the single effects. This is true, in particular, for the embryonal development, for which the risk may almost be doubled, whereas the enhancement of risk is not so great for the proliferation of cells. In some cases the combination results lie even outside the envelope of additivity in the range of supra-additivity. The amount of caffeine necessary for such marked effects, however, is so high (at least 1 mM caffeine for rather long times), that it is almost impossible to reach them in vivo by consumption of caffeine-containing beverages.

Induction of sister chromatid exchange in preimplantation mouse embryos in vitro by 3H‐thymidine or ultraviolet light in combination with caffeine

“…The failure of caffeine to enhance 3H-thymidine-induced SCEs in our experiments is probably not due to the concentration of caffeine used (1 mM), because an enhancement of a number of effects induced by ionizing radiation has been detected in the presence of caffeine at similar concentrations [28]. Caffeine (0.5-2 mM) and X-rays had supra-additive effects on preimplantation development in mouse embryos in vitro [29] and on micronuclei formation 1301. An enhancement of UV effects by caffeine (0.1-0.5 mM) on blastocyst formation has also been reported [15].…”

Supraadditive formation of micronuclei in preimplantation mouse embryos in vitro after combined treatment with X‐rays and caffeine

“…The examination of our results by an isobologram analysis revealed that there is an interaction between caffeine and X-rays. Thus the results obtained in this study are in agreement with our results that combinations of caffeine and X-rays lead to supraadditive effects with respect to the morphological development and to the cell numbers of mouse embryos [36].…”

Comet assay studies indicate that caffeine-mediated increase in radiation risk of embryos is due to inhibition of DNA repair

“…This knowledge is also necessary for the prediction of caffeine effects at low concentrations. The experimental systems only allow analyses at unrealistic high concentrations [corresponding to several hundred cups of coffee or tea per day (MUller et al, 1983)].…”