Objective: To study osteocalcin [correction of osteocakin] (OC) changes in bone and marrow and calcium deposition in bone and cartilage under simulated weightlessness.
Method: Twenty SD rats were randomly divided into 14 d and 28 d tail suspension group and 2 corresponding control groups. Histological samples were in situ hybridized and trichrome stained.
Result: OC expression of bone and marrow of rats were lower in tail suspended rats than that in the control (P<0.05). OC expression in 14 d tail suspended rats were higher than that in 28 d tail suspended group (P<0.05). Mineralization was inhibited, and demineralization of femur [correction of furmer] and cartilage mineralized matrix was prominent. Demineralization was more prominent in 28 d group.
Conclusion: OC levels in bone and marrow of rats were lower after tail suspension. Calcium deposition was inhibited in bone and cartilage. Demineralization was prominent after long term hindlimb unloading.