Effects of male sexual hormone on bone repair in adult male rats

Sexual hormones have important role, in skeletal development and maintaining bone balance. There is little information on effects of testosterone on bone repair. In the present study the effects of testosterone on bone and its repair were studied. Sixty male wistar rats, 12-14 weeks old, weighing between 250-300gr were randomly divided into four groups. The first group were not gonadectomized and did not receive testosterone. The second group were not gonadectomized but were treated with testosterone. The third groups were gonadectomized and treated with testosterone. The fourth group gondectomized but did not receive testosterone. A hole was made on the medial surface of right tibia in all rats. The dose of testosterone was 1mg/kg I.P daily for 3 weeks, at the end of which all rats were killed by ether inhalation. A bone sample was extracted from each rat and was fixed, decalcified, processed, sectioned and was stained by H & E and Trichrome Mason methods. Sections were examined descripitively and quantitatively by light microscopy. Data were analysed by student’s t test and analysis of variance methods. Results showed that in rats treated with testosterone, the rate of bone repair were accelerated, bone density in the defect region was increased, number of osteoblasts were increased (31.3±2.25), and number of osteoclasts were decreased significantly (1.90±0.9). Also, the thickness of periosteum in the region of defect was increased markedly, and dimension and weight of bone were increased significantly (P<0.001). It is concluded that testosterone has positive effect on accelerating bone repair in male rats.