| Objective To monitor the metabolism of type I collagen and the expression of type I collagen in callus tissue during the process of osteoporotic fracture healing with intermittent PTH treatment. Methods The bilateral ovaries of adult female rats were excised to establish the osteoporosis model of rat. Three months later after OVX, the rats had bilateral tibial osteotomy followed by a Kirschner wire intramedullary fixation. Then the rats were divided into two groups: group A (PTH group) were treated with teriparatide (PTH (1-34)) 3 ug/100 g/d subcutaneous injections, once daily; Group B (NS group) were treated with physiological saline (NS) subcutaneous injection at the same dose. At week 1, 2, 4, 8 after the first treatment, specimens the tibia were collected, with some of them evaluated for the COL1A1 mRNA expression level of callus tissue, using the fluorescent quantitative PCR detection, and others for HE staining and immunohistochemical staining of type I collagen. Results On the staining, more new typeⅠcollagen expression and more regular arrangement of collagen fibers could be seen in the PTH groups. The difference was most evident at the 4th week. At the 8th week, typeⅠcollagen fibers were rare in the PTH groups, instead plenty of repaired bone matrix could be seen. The COL1A1 mRNA PCR results: week 1: PTH group 17.258±1.006, NS group 10.022±0.308 (P<0.001); week 2: PTH group 19.548±0.767, NS group 10.208±0.619 (P<0.001); week 4: PTH group 20.892±1.140, NS group 10.182±0.624 (P<0.001); week 8: PTH group 20.708±1.249, NS group 10.560±0.453 (P<0.001). Conclusion In the callus, PTH could improve the expression of COL1A1 mRNA, promote the synthesis and remodeling of typeⅠcollagen, and thus effectively improve the content and arrangement of typeⅠcollagen. |