Although the study was osteomyelitis focused, the findings support the etiopathological role of bacteria in ONJ. In the current study, intermittent PTH administration

for 2 weeks after VC treatment resulted in significantly higher bone mass in intact maxillae but not in intact tibiae. The difference in bone Selleck EX527 responses to PTH is likely due to the presence or absence of trabecular bone. In this study, the metaphyseal trabecular bone area between 1.2 and 3.5 mm distal to the growth plate was assessed to establish baseline bone responses to PTH. As the assessed bone site corresponds to the distal end of the metaphyseal trabecular bone in the proximal tibiae, the trabecular bone at this site NVP-BGJ398 cell line would be resorbed because of OVX in the VC-treated rats. Accordingly, the trabeculation was scarce when ACY-1215 research buy PTH therapy was initiated. The relatively high BMD values of

the maxillae in the VC-VC group suggests the trabecular structure was maintained after OVX, while in the tibiae the low BMD values in the VC-VC group points to significant trabecular bone loss. Therefore, in the intact tibiae that the PTH anabolic effect was not observed was likely due to a trabeculation deficit. Rats in which ALN/DEX treatment was initiated immediately after OVX had greater trabecular bone as evidenced by the high BV/TV and BMD values in the ALN/DEX-VC group. In the ALN/DEX-treated rats, PTH therapy augmented BV/TV and BMD. In fact, all when the PTH anabolic effect was compared between ALN/DEX

and VC treatment, significantly higher bone volume was found in the ALN/DEX-treated rats. These findings may suggest that the amount of existing trabecular bone is a determinant of the degree of PTH anabolic effect in the metaphysis. It is also possible that the short duration (2 weeks) of PTH treatment was not long enough to support significant anabolism at this site. The tibial bone defects were made at the edge of the diaphysis where little trabecular bone, if any, existed. Even the defects were created in such a sparse trabecular bone area in the VC-treated rats, PTH significantly promoted bone fill. PTH also enhanced bone fill in the defects significantly after the ALN/DEX treatment. When the PTH anabolic effect was compared between the osseous defects and undisturbed bone, more powerful PTH anabolic effect was noted in the osseous defect than in undisturbed bone in this study (approximately 47 vs. 6 %). PTH has been shown to promote osseous healing in osteoporotic women [37]. The PTH anabolic effect has also been shown to be pronounced in rapidly growing animals [38]. Nakajima et al. reported that low doses of PTH, which did not increase systemic bone mass, was sufficient to promote osseous healing in rats [39]. These reports together with our findings suggest that PTH’s anabolic actions are greatly enhanced in bone with a high metabolic state.