RESUMEN
This study was made to elucidate the changes in the periarticular connective tissue that can underlie the contracture after spasticity development. Sixteen Wistar rats underwent a spinal cord injury and 16 rats were either sham- or nonoperated. The periarticular connective tissue of the knee joint was assessed with histological, histomorphometric, immunohistochemical, and biochemical analyses. Histological results showed a smaller synovial intima, a dense subintimal and posterior joint capsule without fibrosis, and a disarranged posterior capsule in the spinal cord-injured knees with the flexion contracture. The synovial intima length was shortened only at the posterior capsule. Neither the distribution nor expression of type I and III collagen was affected. Contractures after spinal cord injuries are characterized by synovial intima adhesions. A dense and disarranged capsule may lead to joint stiffness. The alteration of periarticular connective tissues exhibits properties characteristic of the contracture after spasticity development.
Asunto(s)
Tejido Conectivo/patología , Contractura/patología , Articulación de la Rodilla/patología , Traumatismos de la Médula Espinal/patología , Rodilla de Cuadrúpedos/patología , Membrana Sinovial/patología , Animales , Colágeno Tipo I/análisis , Colágeno Tipo III/análisis , Tejido Conectivo/química , Contractura/etiología , Modelos Animales de Enfermedad , Femenino , Ratas , Ratas Wistar , Traumatismos de la Médula Espinal/complicaciones , Rodilla de Cuadrúpedos/química , Membrana Sinovial/química , Factores de TiempoRESUMEN
Skeletal muscles are a target for motoneurons and synthesize neurotrophins, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5). Both at the embryonic stage and the adult stage, the mRNA expression of neurotrophins in skeletal muscles of rats has been reported. However, little was known about the mRNA expression patterns of neurotrophins in skeletal muscles of rats at the young developmental stage. In this study, we investigated the mRNA expressions of BDNF and NT-3 in three different skeletal muscles in 4- to 8- week-old rats using the reverse transcriptional polymerase chain reaction (RT-PCR) method. The expression of BDNF mRNA in the soleus muscle gradually became higher with age from 5 to 8 weeks. But BDNF mRNA in the tibialis anterior and extensor digitorum longus muscles did not change with growth. The expression of NT-3 mRNA did not show a specific tendency during this period. The differences of muscle fiber types, recruitment patterns of the muscles, and roles of neurotrophins may cause these mRNA expression patterns. Neurotrophins are target-derived, activity-dependent neurotrophic factors and are transported retrogradely. There is a possibility that the different expression patterns of neurotrophins in muscles may be involved in the maturation of neuromuscular function in different muscles during the young developmental period.
Asunto(s)
Factor Neurotrófico Derivado del Encéfalo/genética , Músculo Esquelético/metabolismo , Neurotrofina 3/genética , ARN Mensajero/análisis , Animales , Peso Corporal , Ratas , Ratas WistarRESUMEN
Joint contractures following central nervous system injuries remain a prevalent and significant complication, but no reports are available on evidence of contracture formation over time. The objective of this study was to determine the rate of contracture progression and the direction of loss in joint movement following spinal cord injuries (SCI). Forty-eight female Wistar rats were used. Twenty-four experimental rats underwent a spinal cord transection at the level of T8 and 24 control rats underwent a sham-operation. The animals were studied at each of 5 time points: 2, 4, 8, 12, 16, and 24 weeks after surgical intervention. The degree of contractures was assessed by measuring the femorotibial angle on both hindlimbs with the use of a goniometer. Knee joint motion was measured for flexion and extension direction. Knee flexion contractures developed in all experimental rats. The restriction in motion progressed during the first 12 weeks and plateaued thereafter. The contractures were produced almost exclusively by a loss in the extension range of motion. This study defined the time course that contracture progression was more rapid in the early stage after SCI and stabilized in the later stage of injury. Contractures following SCI occurred in flexion at the knees and resulted from a loss of extension. These findings should help guide timely treatment and provide a better understanding of contracture development.