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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.)

Structural and functional changes in the alveolar bone osteoclasts of estrogen-treated rats

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Author(s):
de Souza Faloni, Ana Paula [1] ; Sasso-Cerri, Estela [1] ; Godoy Rocha, Fernanda Regina ; Katchburian, Eduardo [1] ; Cerri, Paulo Sergio [1, 2]
Total Authors: 5
Affiliation:
[1] Fed Univ Sao Paulo Unifesp, Dept Morphol & Genet, Sao Paulo - Brazil
[2] UNESP Univ Estadual Paulista, Dept Morphol, Sch Dent, Lab Histol & Embryol, BR-14801903 Sao Paulo - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Journal of Anatomy; v. 220, n. 1, p. 77-85, JAN 2012.
Web of Science Citations: 11
Abstract

This study investigated structural and functional features of apoptotic alveolar bone osteoclasts in estrogen-treated rats. For this purpose, 15 female rats 22 days old were divided into three groups: Estrogen (EG), Sham (SG) and Control (CG). The rats of EG received daily intramuscular injection of estrogen for 7 days. The SG received only the oil vehicle. Maxillary fragments containing alveolar bone were removed and processed for light and transmission electron microscopy. Area (OcA) and number of nuclei (OcN) and bone resorption surface per TRAP-positive osteoclasts (BS/OC) were obtained. Vimentin, caspase-3 and MMP-9 immunoreactions, TUNEL/TRAP and MMP-9/TUNEL combined reactions were performed. In EG, the OcA, OcN and BS/Oc were reduced. Moreover, osteoclasts showed cytoplasm immunolabelled by caspase-3 and a different pattern of vimentin expression in comparison with CG and SG. MMP-9 expression was not affected by estrogen and the TUNEL-positive osteoclasts were MMP-9-immunolabelled. In EG, ultrastructural images showed that apoptotic osteoclasts did not exhibit ruffled borders or clear zones and were shedding mononucleated portions. TRAP-positive structures containing irregular and dense chromatin were partially surrounded by fibroblast-like cells. In conclusion, the reduction in the BS/Oc may be due to reduction in OcA and OcN; these effects seem to be related to vimentin disarrangement rather than to an interference of estrogen with osteoclast MMP-9 expression. Osteoclast apoptosis involves caspase-3 activity and vimentin degradation; these cells release portions containing one apoptotic nucleus and, subsequently, undergo fragmentation, giving rise to apoptotic bodies. (AU)