Evaluation of the long-term skeletal effect induced by teratogen 5-aza-2′deoxycytidine on offspring of high (C3H/HeJ) and low (C57BL/6J) bone mass phenotype mice

The long term skeletal effects of antenatal exposure to teratogen 5-deoxy-2′-cytidine (5-AZA) were studied using two inbred strains, C3H/HeJ (C3H, with inherently stronger bones) and C57Bl/6J (C57, with weaker bones). We previously reported that in-utero exposure to 5-AZA resulted in loss of bone quality in 3- and 6-mo-old C3H offspring. In this study, we further examined whether the long-term effects of an acute teratogenic exposure are still evident in older mice. Bone phenotypes of 12 mo-old mice exposed to a single injection of 5-AZA on day 10 of their mother's pregnancy were evaluated by micro-computed tomography and compared to the untreated controls. The main observation of this study is that 5-AZA-induced loss of bone length was registered in 12-mo-old C57 and C3H males. As expected, we did not find differences in the 3rd lumbar vertebra since in-utero exposure to 5-AZA was shown to affect the limb buds but not the axial skeleton. Trajectory of changes in bone phenotypes from ages 3 mo through 6 mo to 12 mo was also compared; 5-AZA-exposed C57 males had consistently lower femoral length and trabecular BMD than age-matched controls. In summary, by characterizing teratogen-exposed C57 and C3H mice, we further confirmed that the adaptive response to antenatal insults continue into mid-life of the mice as well as there is a sex-specificity of these responses.