RESUMO
The aim of this study was to evaluate the effects of laser phototherapy on the degenerative modifications on the articular cartilage after the anterior cruciate ligament transection (ACLT) in the knee of rats. Eighty male rats (Wistar) were distributed into four groups: intact control group (IG), injured control group (CG), injured laser treated group at 10 J/cm(2) (L10), and injured laser treated group at 50 J/cm(2) (L50). Animals were distributed into two subgroups, sacrificed in 5 and 8 weeks postsurgery. The ACLT was used to induce knee osteoarthritis in rats. After 2 weeks postsurgery, laser phototherapy initiated and it was performed for 15 and 30 sessions. The histological findings revealed that laser irradiation, especially at 10 J/cm(2), modulated the progression of the degenerative process, showing a better cartilage structure and lower number of condrocytes compared to the other groups. Laser phototherapy was not able to decrease the degenerative process measured by Mankin score and prevent the increase of cartilage thickness related to the degenerative process. Moreover, it did not have any effect in the biomodulation of the expression of markers IL1ß, tumor necrosis factor-α, and metalloprotein-13. Furthermore, laser irradiated animals, at 50 J/cm(2) showed a lower amount of collagen type 1.
Assuntos
Cartilagem Articular/efeitos da radiação , Inflamação/patologia , Osteoartrite/terapia , Fototerapia/métodos , Análise de Variância , Animais , Ligamento Cruzado Anterior/patologia , Ligamento Cruzado Anterior/efeitos da radiação , Ligamento Cruzado Anterior/cirurgia , Cartilagem Articular/patologia , Colágeno Tipo I/metabolismo , Modelos Animais de Doenças , Imuno-Histoquímica , Masculino , Osteoartrite/patologia , Fototerapia/efeitos adversos , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/análise , Fator de Necrose Tumoral alfa/metabolismoRESUMO
We evaluate the effects of low-level laser therapy (LLLT) on the histological modifications and temporal osteogenic genes expression during the initial phase of bone healing in a model of bone defect in rats. Sixty-four Wistar rats were divided into control and treated groups. Noncritical size bone defects were surgically created at the upper third of the tibia. Laser irradiation (Ga-Al-As laser 830 nm, 30 mW, 0.028 cm², 1.071 W/cm², 1 min and 34 s, 2.8 Joules, 100 J/cm²) was performed for 1, 2, 3, and 5 sessions. Histopathology revealed that treated animals presented higher inflammatory cells recruitment, especially 12 and 36 h postsurgery. Also, a better tissue organization at the site of the injury, with the presence of granulation tissue and new bone formation was observed on days three and five postsurgery in the treated animals. The quantitative real time polymerase chain reaction showed that LLLT produced a significantly increase in mRNA expression of Runx-2, 12 h and three days post-surgery, a significant upregulation of alkaline phosphatase mRNA expression after 36 h and three days post-surgery and a significant increase of osteocalcin mRNA expression after three and five days. We concluded that LLLT modulated the inflammatory process and accelerated bone repair, and this advanced repair pattern in the laser-treated groups may be related to the higher mRNA expression of genes presented by these animals.
Assuntos
Regeneração Óssea/fisiologia , Terapia com Luz de Baixa Intensidade/métodos , Osteogênese/genética , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Análise de Variância , Animais , Regeneração Óssea/genética , Regeneração Óssea/efeitos da radiação , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Histocitoquímica , Masculino , Osteocalcina/genética , Osteocalcina/metabolismo , RNA Mensageiro/genética , Ratos , Ratos Wistar , Tíbia/lesões , Tíbia/efeitos da radiaçãoRESUMO
We compared the response of articular cartilage subjected to muscle stretching at different frequencies after joint immobilization. Wistar rats with immobilized left hind limbs were classified into the following groups: immobilization, immobilization followed by muscle stretching applied daily (group IS7) or three times a week (IS3), muscle stretching applied daily (S7) or three times a week (S3), and a control group (C) that underwent no intervention. We then evaluated the cartilage for cellularity, loss of proteoglycans, collagen density, and immunostaining of fibronectin and chondroitin 4-sulfate. Group IS7 showed a significant increase in cellularity and significant loss of proteoglycan compared with the control. In addition, IS7 group had less proteoglycan than IS3. Thin collagen fibrils were significantly reduced in IS7 rats, compared with IS3 and C. There was a significant decrease in the amount of thick fibrils in all groups compared with the control. Groups IS7 and IS3 showed significantly more intense fibronectin immunostaining than the other groups. Our results show that if applied daily after immobilization, muscle stretching is harmful to articular cartilage. However, when applied on alternate days, muscle stretching preserves the components of articular cartilage. We suggest that the latter frequency is more suitable for treatment.
Assuntos
Cartilagem Articular/fisiologia , Elevação dos Membros Posteriores , Músculo Esquelético/fisiologia , Animais , Fenômenos Biomecânicos , Sulfatos de Condroitina/metabolismo , Colágeno/metabolismo , Fibronectinas/metabolismo , Imuno-Histoquímica , Articulações/fisiologia , Masculino , Proteoglicanas/metabolismo , Ratos , Ratos WistarRESUMO
The aim of study was to evaluate the progression of the ankle articular cartilage alterations after a post-immobilization muscle stretching. Twenty-nine Wistar rats were separated into five groups: C--control, S--stretched, SR--stretch recovery, IS--immobilized and stretched, and ISR--immobilized stretched recovery. The immobilization was maintained for 4 weeks and the left ankle was then stretched manually through a full dorsal flexion for 10 times for 60 s with a 30 s interval between each 60 s period, 7 days/week for 3 weeks. The recovery period was of 7 weeks. At the end of the experiment, the left ankles were removed, processed in paraffin, and stained in hematoxylin-eosin and safranin O. Two blinded observers evaluated the articular cartilage using the Mankin grading system (cellularity, chondrocyte cloning, and proteoglycan content) through light microscopy, and performed the morphometry (cellularity, total thickness, non-calcified thickness, and calcified thickness measures). Both the Mankin grading system and the morphometric analysis showed that the ISR group presented the most increased cellularity among the groups. The IS and SR groups showed the highest proteoglycan loss, and the ISR group showed the same content of proteoglycan observed in the C group. No significant differences were found in the chondrocyte cloning, the total cartilage thickness, the non-calcified cartilage thickness, and the calcified cartilage thickness among the groups. The results suggest that the cartilage can recover the proteoglycan loss caused by immobilization and stretching, probably because of the increased chondrocyte density. Therefore, the ankle articular cartilage responded as to repair the metabolic deficits.