Long-term simulated weightlessness impaired odontoblasts' synthetical ability and secretory activity

Long-term simulated weightlessness on the ground induces changes of metabolism in variety organs followed with the changes of expression pattern in many genes. In tooth, reduction of DSPP expression in rat odontoblasts was detected in our previous study after the rats were tail suspended for 4 weeks. However, the mechanism underlying this change is unclear. Objectives: The aim of the present study were to investigate whether such change was related to the ultrastructural change in rat odontoblasts under simulated weightlessness. Methods: 6 SD rats were divided randomly into 2 groups,3 for tail suspended to simulate weightlessness in space and 3 for control. Rats were sacrificed after 28days, and the ultrastructure of odontoblasts situated in predentin at mesiobuccal cusp of the first molar were observed under transmission electron microscopy. Results: Compare to the control group, reduction of organelles,especial rough endoplasmic reticulum in odontoblasts were detected in tail-suspended group.In addition, decreased matrix and collegen fiber around the cell were observed in experimental ones as well. Conclusions: The ultrastructural changes in rat odontoblasts of those tail suspended for 28 days indicated that long-term simulated weightlessness impair synthetical ability and secretory activity of odontoblasts ,and thus may lead to the reduction of DSPP expression in odontoblasts.