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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Reduced RANKL expression impedes osteoclast activation and tooth eruption in alendronate-treated rats

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Author(s):
Bradaschia-Correa, Vivian [1] ; Moreira, Mariana M. [1] ; Arana-Chavez, Victor E. [1]
Total Authors: 3
Affiliation:
[1] Univ Sao Paulo, Lab Oral Biol, Dept Biomat & Oral Biol, Sch Dent, BR-05508000 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Cell and Tissue Research; v. 353, n. 1, p. 79-86, JUL 2013.
Web of Science Citations: 11
Abstract

The creation of the eruption pathway requires the resorption of the occlusal alveolar bone by osteoclasts and signaling events between bone and dental follicle are necessary. The aim of the present study has been to evaluate the effect of alendronate on osteoclastogenesis and the expression of the regulator proteins of osteoclast activation, namely RANK, RANKL and OPG, in the bone that covers the first molar germ. Newborn Wistar rats were treated daily with 2.5 mg/kg alendronate for 4, 8, 14, 21 and 28 days, whereas controls received sterile saline solution. At the time points cited, maxillae were fixed, decalcified and processed for light and electron microscopic analysis. TRAP histochemistry was performed on semi-serial sections and the osteoclasts in the occlusal half of the bony crypt surface were counted. TUNEL analysis was carried out on paraffin sections. The occlusal bone that covers the upper first molar was removed in additional 4- and 8-day-old alendronate-treated and control rats in which the expression of RANK, RANKL and OPG was analyzed by SDS-polyacrylamide gel electrophoresis and Western blotting. TRAP-positive osteoclasts were more numerous in the alendronate group at all time points, despite their unactivated phenotype and the presence of apoptotic cells. RANKL expression in the alendronate specimens was inhibited at all time points, unlike in controls. Our findings indicate that the expression of RANKL in the occlusal portion of the bony crypt is unrelated to osteoclast recruitment and differentiation but is crucial to their activation during the creation of the eruption pathway. (AU)