Experimental Pharmacologic Studies on the Alveolar Bone Resorption and its Recovery Mechanism.

1.本文观察了低钙饮食（0.05%Ca，0.35%P）大鼠磨牙区牙槽骨的组织学变化。低钙饮食后，牙周松质骨发生了进行性骨吸收，但牙槽骨本身仍存在，提示牙槽骨在咬合中支持牙齿功能活动的功能仍被削弱.为了研究牙槽骨骨吸收的恢复过程，给大鼠低钙饮食9天，随后用对照饮食（0.5%Ca，0.35%P）代替11天。对照组大鼠的骨体积明显增加，但不足以恢复低钙饮食引起的骨吸收。提示骨吸收一旦发生，与低钙饮食诱导骨吸收的时间相比，需要更长的时间来恢复丢失的骨量.为了阐明破骨细胞在骨吸收过程中的细胞骨架系统的功能，从大鼠胫骨中分离破骨细胞，并在微管抑制剂秋水仙碱的处理下进行培养。当微管被秋水仙素破坏时，破骨细胞收缩。它们被分成几个细胞部分，每个细胞部分都朝着不同的方向移动。这些结果表明，微管是重要的，以维持破骨细胞的细胞形状作为一个细胞调节剂，它们控制每个细胞部分的运动，以保持多核破骨细胞作为一个细胞的细胞活动。

1. Histological changes of alveolar bone in the area of molar tooth were investigated in the rats fed a low calcium diet (0.05% Ca, 0.35% P). Bone resorption was found to be progressively appeared in the cancellus bone around the tooth after feeding a low calcium diet, however, the alveolar bone proper remained suggesting that the function of alveolar bone to support the functional activity of tooth in occlusion was still maintained.2. To investigate the recovery process from the bone resorption of alveolar bone, rats were given a low calcium diet for 9 days and were subsequently replaced by a control diet (0.5% Ca, 0.35% P) for 11 days. The bone volume increased significantly after feeding the control diet, but it was not enough to recover the bone resorption induced by the low calcium diet. It was suggested that once bone resorption is occurred, a longer period is needed to recover the loss of bone volume compared with the period to induce bone resorption by the low Ca diet.3. To elucidate the function of the cytoskeletal system in osteoclasts during bone resorption, osteoclasts were isolated from the tibia of rats and were cultured under the treatment of a microtubule inhibitor, colchicine. Osteoclasts were contracted when microtubules were destroyed by colchicine. They were separated into several cell portions and each cell portion was moving toward a different direction. These results indicated that microtubules are important to maintain the cell shape of osteoclasts as a cytoskelton and that they control the movement of each cell portion in order to keep the cellular activities of a multinucleated osteoclast being as one cell.