Effects of intermittent administration of parathyroid hormone on bone augmentation in rat calvarium.

Abstract

This study examined the effects of parathyroid hormone (PTH) on bone augmentation beyond the skeletal envelope within a plastic cap in rat calvaria. The calvaria of 30 rats were exposed, and 2 plastic caps were placed on each. Each of the 10 rats was treated with 35 or 105 μg/kg (PTH-35, PTH-105) PTH 3 times per week. The control group was injected with sterile saline 3 times per week. Micro-computed tomography (CT) imaging was performed every 2 weeks for 12 weeks. Micro-CT and histological sections were used to determine the amount of bone augmentation within the plastic caps. Bone volume (BV) was calculated using BV-measuring software. The histomorphometric and histological analyses showed that the amount of bone augmentation was increased significantly in the PTH groups compared with the controls at 12 weeks. The PTH-105 group showed significantly more bone augmentation and osteoblasts compared with the PTH-35 group. These results indicate that the higher the dose of intermittent PTH administered, the greater the amount of bone formation beyond the skeletal envelop in the rat calvarium.