Expression of type I collagen, MMP-2, MMP-8, MMP-14 and TIMPS in the periodontal ligament of rat incisors in normal and altered functional conditions / Expressão de colageno tipo I, MMP-2, MMP-8, MMP-14 eTIMPS no ligamento periodontal de incisivos de ratos em condições funcionais normal e alteradas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Periodontal ligament is a connective tissue that provides anchorage and support to the tooth, and it has a probable role in the tooth eruption. The extracelular matrix consists predominantly of collagen type I (Col-1) and the turnouver of collagen fibers is intense. Matrix metalloproteinases (MMPs) are members of a family of enzymes capable to degrade almost all components of the extracellular matrix. They are present in the periodontal ligament. It is supposed that tooth functional conditions alterations may promote changes in the metabolism of periodontal ligament cells, modifying the balance between the synthesis of extracellular matrix proteins and their degradation by MMPs. The aim of the present study is to quantify the levels of mRNA of Col-1, MMP-2, MMP-8, MMP-14, TIMP-1 and TIMP-2, identify the cells expressing these mRNA and locate these proteins in the periodontal ligament of rat incisors submitted to altered functional conditions. Lewis male rats were randomly assigned to 4 groups and their lower incisors were submitted to different functional conditions: normofunctional, hipofunctional, hiperfunctional and restraint, during 7 or 14 days. The teeth were extracted and the periodontal ligament was collected by gently scaling of the distal, lingual and mesial tooth surface. Total RNA was extracted and the synthesis of the cDNA was performed for Relative PCR Quantification. In situ hybridization and immunohistochemistry were performed to detect the cell expression and the proteins localization in the periodontal ligament. Five rats for each functional condition were sacrified after 7 and 14 experimental days.The rat hemimandubles were removed for histological processing to obtain 3µm transversal sections. Analysis of the expression of Col-1, MMPs and TIMPs showed a down-regulation for all genes in the groups studied in relation to the normofuctional group. Significant down-regulation (p<0,05) was found in the groups treated during 7 days, and increased levels of mRNA was related to 14 days of treatment. Significant increased levels of mRNA (p<0,05) were found only for MMP-2 to the hipofunctional group at 7 days. Reduction (p<0,05) of the levels of mRNA for MMP-8 in the restraint group at 7 and 14 days seems to be related to the increased levels of its inhibitor, TIMP-1. MMPs and TIMPs were found been expressed in the periodontal ligament by fibroblasts, cementoblasts, osteoblasts and osteoclasts. Col-1 was localized at the region adjacent to the alveolar bone, whereas TIMP-2 was concentrated adjacent to the tooth region of the periodontal ligament. The results obtained suggest that the alterations on the functional conditions of the rat incisors produce changes in the metabolism of the periodontal ligament tissue by changing the levels of COL-1, MMPs and TIMPs. Up-regulation peaks or downregulation peaks seem to be conduced to the normal levels of expression along the experimental time. The balance between production of Col-1, MMPs and TIMPs may have an important role in the control of the eruption rate of rat incisors

ASSUNTO(S)

expressão genica periodontium in situ hibridization metalloproteinase periodonto reação em cadeia de polimerase hibridização in situ metaloproteinase polymerase chain reaction gene expression

ACESSO AO ARTIGO

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