Immunocytochemical Study of Amelogenin Deposition During the Early Odontogenesis of Molars in Alendronate-treated Newborn Rats
Luciana F. Massa 1, Vivian Bradaschia-Correa 1 and Victor E. Arana-Chavez 1*
1 Laboratory of Mineralized Tissue Biology, Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
* To whom correspondence should be addressed. E-mail: vearana{at}usp.br.
Submitted on October 5, 2005
Accepted on 23 January 2006
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Abstract |
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Newborn rats were treated with sodium alendronate with the purpose to study how enamel is formed and what is the effect of alendronate during early odontogenesis. Ultrastructural analysis combined with high-resolution immunocytochemistry for amelogenin was carried out. Twelve rats were subjected to daily subcutaneous injections of 2.5 mgp kg-1 d-1 of sodium alendronate for 3 d on their dorsal region, while three rats were daily injected with saline solution as a control. Molar tooth germs from 3-d rats were fixed under microwave irradiation in 0.1% glutaraldehyde + 4% formaldehyde buffered at pH 7.2 with 0.1M sodium cacodylate. The specimens were left undecalcified, postfixed with osmium tetroxide, dehydrated and embedded in LR White resin. Ultrathin sections were incubated with a chicken anti - 24 kDa rat amelogenin antibody, with a secondary antibody and finally with a protein A-gold complex. Large patches of amelogenin were present over the unmineralized mantle dentine and at early secretory ameloblasts. At more advances stages, they were also detected at the enamel matrix, as well as in the mineralized dentine, at the periodontoblastic space of the dentinal tubules, and at the predentine. It is likely that the main effect of alendronate at early stages of odontogenesis is the increase of synthesis / secretion of amelogenin promoting its deposition within the forming dentine and enamel.
Key Words:
amelogenin, alendronate, odontogenesis, ameloblasts, odontoblasts, bisphosphonates, immunocytochemistry
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