RESUMO
BACKGROUND AND OBJECTIVE: This study investigated the effect of occlusal contact loss (induced by tooth shortening), on matrix metalloproteinase (MMP)-2, membrane type 1-MMP (MT1-MMP) and tissue inhibitor of the MMP-2 (TIMP-2) expressions in the periodontal ligament of the rat incisor, as well as eruption rate, resistance and collagen organization. MATERIAL AND METHODS: Male Wistar rats were distributed into a control group, denominated normofunctional group, whose lower teeth underwent a normal eruption process; and a hypofunctional group, whose lower left incisor teeth were shortened every 2 days during 14 days. Parameters were evaluated on the first, seventh and 14th days and the eruption rate was determined according to the size of the incisor during the eruption process. MMP-2 activity was determined by zymography and the expressions of the MT1-MMP and TIMP-2 proteins were quantitated by western blot. Collagen protein organization, as indicated by the birefringence of the periodontal ligament, was analyzed under polarized light and the periodontal ligament's resistance was determined from the load necessary to inject the incisor into its alveolar space, before extraction. RESULTS: Loss of occlusal contact, in rats submitted to hypofunctional eruption, increased MMP-2 activity and eruption rate, but decreased MT1-MMP and TIMP-2 expression and disrupted collagen organization in the periodontal ligament, consequently reducing periodontal ligament resistance. CONCLUSION: We conclude that, after incisor eruption, occlusal contact may be an important factor for regulating the remodeling and the physiological resistance of the periodontal ligament against the continuous eruption process observed in rat incisors.
Assuntos
Colágeno/metabolismo , Oclusão Dentária , Incisivo/crescimento & desenvolvimento , Metaloproteinase 14 da Matriz/metabolismo , Metaloproteinase 2 da Matriz/metabolismo , Ligamento Periodontal/metabolismo , Inibidor Tecidual de Metaloproteinase-2/metabolismo , Animais , Ligamento Periodontal/patologia , Ratos Wistar , Erupção DentáriaRESUMO
BACKGROUND AND OBJECTIVE: Doxycycline is an antibiotic agent that inhibits the activity of matrix metalloproteinases (MMPs) present in the extracellular matrix. In this study, the rat incisor was submitted to a hypofunctional condition, and the effects of doxycycline (80 mg/kg/d) on the expression and activity of MMP-2, as well as on eruption rate, were determined in the odontogenic region and in the periodontal ligament for 14 d. MATERIAL AND METHODS: Rats were distributed into four groups: normofunctional (NF); doxycyline normofunctional (DNF); hypofunctional (HP); and doxycyline hypofunctional (DHP). The left lower incisors of 10 rats were shortened every 2 d, using a high-rotation drill, to produce the HP and DHP groups, after starting doxycycline treatment (80 mg/kg) by gavage. Eruption was measured using a millimeter ocular, from the gingival margin to the top of the tooth in the HP and DHP groups, and also by a mark made in the tooth previously, in the NF and DNF groups. The hemimandibles were removed and the teeth were extracted to collect the periodontal and odontogenic tissues for immunohistochemical analyses and zymography. RESULTS: The eruption rates were higher in the HP and the DHP groups than in the NF and DNF groups, respectively (p < 0.05). In the odontogenic region, neither of the treatments changed the expression and activity of MMP-2. In the HP group, the shortening treatment decreased the expression, but not the activity, of MMP-2, while doxycycline was able to inhibit the increase of expression and activity of MMP-2. CONCLUSION: We conclude that the inhibition of MMP-2 by doxycycline, during incisor shortening, was not enough to alter the eruption rate, which suggests that MMP-2 may have an important role in the turnover of extracellular matrix of the periodontal ligament during the tooth-eruption process.
Assuntos
Doxiciclina/farmacologia , Incisivo/crescimento & desenvolvimento , Metaloproteinase 2 da Matriz/efeitos dos fármacos , Inibidores de Metaloproteinases de Matriz/farmacologia , Ligamento Periodontal/enzimologia , Erupção Dentária/efeitos dos fármacos , Animais , Expressão Gênica/efeitos dos fármacos , Incisivo/efeitos dos fármacos , Masculino , Ligamento Periodontal/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
Two mesophilic streptomycetes (S. violaceoruber and S. spiroverticillatus) were selected to study their Poly R-478 decolorization ability and lignocellulose solubilizing activity. Both strains were able to degrade Poly R-478 dye and ferulic acid during growth on a minimal salts medium. The Poly R-478 decolorizing activities of both strains were induced by adding different carbon sources to the culture media. S. violaceoruber could decolorize 63% of Poly R-478 after 24 h. Both strains could solubilize straw and produce acid-precipitable polymeric lignin (APPL) with different efficiency. From the major extracellular enzymes recovery of both strains on rice and wheat straw, we can predicate that the biodegradation process was partial indicating a possible utilization in biological delignification.
Assuntos
Antraquinonas/metabolismo , Lignina/metabolismo , Polímeros/metabolismo , Streptomyces/metabolismo , Biotransformação , Ácidos Cumáricos/metabolismo , Meios de Cultura/química , Oryza/metabolismo , Caules de Planta/metabolismo , Streptomyces/crescimento & desenvolvimento , Triticum/metabolismoRESUMO
Two mesophilic streptomycetes (S. violaceoruber and S. spiroverticillatus) were selected to study their Poly R-478 decolorization ability and lignocellulose solubilizing activity. Both strains were able to degrade Poly R-478 dye and ferulic acid during growth on a minimal salts medium. The Poly R-478 decolorizing activities of both strains were induced by adding different carbon sources to the culture media. S. violaceoruber could decolorize 63% of Poly R-478 after 24 h. Both strains could solubilize straw and produce acid-precipitable polymeric lignin (APPL) with different efficiency. From the major extracellular enzymes recovery of both strains on rice and wheat straw, we can predicate that the biodegradation process was partial indicating a possible utilization in biological delignification.
Assuntos
Antraquinonas/metabolismo , Lignina/metabolismo , Polímeros/metabolismo , Streptomyces/metabolismo , Biotransformação , Ácidos Cumáricos/metabolismo , Meios de Cultura/química , Oryza/metabolismo , Caules de Planta/metabolismo , Streptomyces/crescimento & desenvolvimento , Triticum/metabolismoRESUMO
Two mesophilic streptomycetes (S. violaceoruber and S. spiroverticillatus) were selected to study their Poly R-478 decolorization ability and lignocellulose solubilizing activity. Both strains were able to degrade Poly R-478 dye and ferulic acid during growth on a minimal salts medium. The Poly R-478 decolorizing activities of both strains were induced by adding different carbon sources to the culture media. S. violaceoruber could decolorize 63% of Poly R-478 after 24 h. Both strains could solubilize straw and produce acid-precipitable polymeric lignin (APPL) with different efficiency. From the major extracellular enzymes recovery of both strains on rice and wheat straw, we can predicate that the biodegradation process was partial indicating a possible utilization in biological delignification.
Assuntos
Antraquinonas/metabolismo , Lignina/metabolismo , Polímeros/metabolismo , Streptomyces/metabolismo , Biotransformação , Ácidos Cumáricos/metabolismo , Meios de Cultura/química , Oryza/metabolismo , Caules de Planta/metabolismo , Streptomyces/crescimento & desenvolvimento , Triticum/metabolismoRESUMO
The aim of this study was to further define the relationship between cell proliferation and the rate of tooth eruption in the rat incisor. Vinblastine is a drug that blocks cellular mitosis and was used to inhibit cell proliferation in the odontogenic region of rat incisors that were submitted to a shortening treatment or to higher masticatory forces. Male Wistar rats were divided into five groups: normofunctional (control group for incisor eruption), hypofunctional (incisor submitted to eruption acceleration), hyperfunctional (incisors under higher masticatory forces), hypofunctional with vinblastine and hyperfunctional with vinblastine. In incisors submitted to shortening procedures, a significant decrease in the eruption rate and cell proliferation was observed two days after vinblastine injection, suggesting that incisor eruption is dependent on cell proliferation.
Assuntos
Proliferação de Células , Incisivo/citologia , Erupção Dentária , Animais , Fenômenos Biomecânicos , Força de Mordida , Proliferação de Células/efeitos dos fármacos , Incisivo/efeitos dos fármacos , Masculino , Odontogênese , Ratos , Ratos Wistar , Fatores de Tempo , Erupção Dentária/efeitos dos fármacos , Vimblastina/farmacologiaRESUMO
The enamel-related periodontium (ERP) in rat incisors is related to bone resorption. In these teeth the face of the socket related to the enamel is continuously removed at the inner side and newly formed at the outer side. CSF-1, RANKL and OPG are regulatory molecules essential for osteoclastogenesis. To verify the effects of impeded eruption on bone remodeling, the tooth eruption was prevented by immobilization of lower rat incisor and CSF-1, RANKL and OPG distribution in the ERP was analyzed after 18 days of immobilization and in normal eruption. The region of the alveolar crest of the rat incisor was used. Immunohistochemistry and tartrate-resistant acid phosphatase (TRAP) were performed. The immunostaining of the dental follicle was quantified using Leica QWin software. Positive-TRAP osteoclasts were counted, and both groups were compared. In the normal incisor, the number of osteoclasts was significantly greater than in the immobilized tooth. In the dental follicle, there was no significant difference in the immunostaining intensity for CSF-1 and OPG between the groups (p > 0.05), but for RANKL the immobilized incisor group showed immunostaining intensity smaller than the normal incisor group (p < 0.01). These findings suggest that changes in the ERP, in the immobilized incisor, modify the RANKL/OPG ratio, in the presence of CSF-1, altering the metabolism of cells that participate in the bone remodeling.