Avaliação de um modelo animal de paralisia cerebral sobre a morfologia do músculo extensor longo dos dedos

• Autor(a) principal: Covatti, Caroline
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UNIOESTE
• Texto Completo: http://tede.unioeste.br/handle/tede/3258
• topic: Modelo animal de paralisia cerebral; Lipopolissacarídeo; Anóxia perinatal; Lipopolissacarídeo; Restrição sensório-motora; Morfologia muscular; Animal model of cerebral palsy; Lipopolysaccharide; Perinatal anoxia; Sensorimotor restriction; Muscular morphology; CIENCIAS BIOLOGICAS

Cerebral palsy (CP) is characterized by movement and postural disorders that limit the individual‘s activity, and is attributed to the occurrence of non-progressive disturbances during the development of the fetal or infant brain. Animal models have been used in an attempt to reproduce the lesions and characteristics of CP. However, there is still no intervention capable of reproducing the characteristics of this pathology in the experimental area. Thus, the objective of this study was to verify the effects of a CP model that combines prenatal exposure to lipopolysaccharide (LPS), perinatal anoxia and sensorimotor restriction on the muscle fibers and neuromuscular junctions (NMJs) of the extensor digitorum longus (EDL) of rats. Male Wistar pups were separated into two groups: Control group (CTL - n = 10) - pups of mothers injected with saline during pregnancy and Cerebral Palsy Group (CP - n = 10) - pups of mothers injected with LPS during pregnancy. submitted to perinatal anoxia and sensorimotor restriction. On the day of birth, the offspring of the CP group were placed in a closed chamber with nitrogen flow (100%) to perform the perinatal anoxia. Additionally, from the first postnatal day (P1) to P30, those pups were also submitted to sensorimotor restriction by immobilizing the hind limbs. Motor performance was assessed in both groups during open field tests on P29 and P45. After euthanasia, EDL muscle samples were processed for morphological and morphometric analysis of the muscle fibers and NMJs. Regarding motor performance, the time of locomotion and the number of rearings were significantly lower in the CP group compared to CTL group at 29 days of age (p <0.001 and p <0.01, respectively). At 45 days of age, the time of locomotion of the animals in the CP group was also lower in relation to the CTL group (p <0.05). The total body weight, weight and length of the EDL muscle were 18%, 17% and 15% lower, respectively, in the CP group in relation to the CTL. The animals in the CP group presented hypertrophy of the type IIB fibers. However, regarding the other fibers there was no difference between groups. There were no differences between groups in the number of muscle fiber types I, IIA and IIB. The nuclei/fiber ratio, and the capillary/fiber ratio, were significantly higher in the CP group (21% and 18%, respectively). Regarding the intrafusal fibers, the animals from the CP group presented atrophy in 26% of the cross-sectional area and a reduction of 26% in the muscle spindle area. Intramuscular collagen increased by 34% in the animals from the CP group. The ultrastructural study of the EDL muscle in the CP group showed myofibrillar disruption and Z-line disorganization and dissolution. The NMJs in the CP group presented an increase of 22% in area and 11% in diameter when compared to the CTL group. In conclusion, the CP animal model that uses injections of LPS, perinatal anoxia and sensorimotor restraint produces motor deficits that are also observed in children with CP.