Morphofunctional characteristics of skeletal muscle in rats with cerebral palsy.

Knowledge of skeletal muscle adaptations is important to understand the functional deficits in cerebral palsy (CP). This study aimed to investigate the morphofunctional characteristics of skeletal muscle in a CP animal model. Initially, pregnant Wistar rats were injected intraperitoneally with saline or lipopolysaccharide over the last five days of pregnancy. The control group (n = 8) consisted of male pups born to females injected with saline. The CP group (n = 8) consisted of male pups born to females injected with lipopolysaccharide, which were submitted to perinatal anoxia [day of birth, postnatal day 0 (P0)] and sensorimotor restriction (P1-P30). The open-field test was undertaken on P29 and P45. On P48, the animals were weighed, and the plantaris muscle was collected and its weight and length were measured. Transverse sections were stained with haematoxylin-eosin, NADH-TR, Masson's trichrome and non-specific esterase reaction for analysis. and transmission electron microscopy was performed. In the CP group, reductions were observed in mobility time, number of crossings and rearing frequency, body weight, muscle weight and length, and nucleus-to-fibre and capillary-to-fibre ratios. There was a statistically significant increase in the percentage area of the muscle section occupied by collagen; reduction in the area and increase in the number of type I muscle fibres; increase in myofibrillar disorganization and Z-line disorganization and dissolution; and reduction in the area and largest and smallest diameters of neuromuscular junctions. Thus this animal model of CP produced morphofunctional alterations in skeletal muscle, that were associated with evidence of motor deficits as demonstrated by the open-field test.

Characterization of a cerebral palsy-like model in rats: Analysis of gait pattern and of brain and spinal cord motor areas.

In an attempt to propose an animal model that reproduces in rats the phenotype of cerebral palsy, this study evaluated the effects of maternal exposure to bacterial endotoxin associated with perinatal asphyxia and sensorimotor restriction on gait pattern, brain and spinal cord morphology. Two experimental groups were used: Control Group (CTG) - offspring of rats injected with saline during pregnancy and Cerebral Palsy Group (CPG) - offspring of rats injected with lipopolysaccharide during pregnancy, submitted to perinatal asphyxia and sensorimotor restriction for 30days. At 29days of age, the CPG exhibited coordination between limbs, weight-supported dorsal steps or weight-supported plantar steps with paw rotation. At 45days of age, CPG exhibited plantar stepping with the paw rotated in the balance phase. An increase in the number of glial cells in the primary somatosensory cortex and dorsal striatum were observed in the CPG, but the corpus callosum thickness and cross-sectional area of lateral ventricle were similar between studied groups. No changes were found in the number of motoneurons, glial cells and soma area of the motoneurons in the ventral horn of spinal cord. The combination of insults in the pre, peri and postnatal periods produced changes in hindlimbs gait pattern of animals similar to those observed in diplegic patients, but motor impairments were attenuated over time. Besides, the greater number of glial cells observed seems to be related to the formation of a glial scar in important sensorimotor brain areas.

Caracterização de um modelo de paralisia cerebral em ratos: cognição e estrutura do hipocampo e amígdala / Characterization of a model of cerebral palsy in rats: cognition and structureof the hippocampus and amygdala

FUNDAMENTO: A paralisia cerebral (PC) é caracterizada por distúrbios do movimento e da postura, que podem estar associados a déficits cognitivos. Tais comprometimentos são atribuídos a lesões não progressivas ao encéfalo em desenvolvimento. No âmbito experimental, modelos animais dessa condição clínica capazes de reproduzir o fenótipo e as alterações estruturais vistas em humanos são escassos. OBJETICO: Investigar as repercussões da indução de um modelo de PC sobre a função cognitiva e estrutura do hipocampo e amígdala em ratos Wistar. MÉTODOS: Dois grupos experimentais foram utilizados: 1) Controle - filhotes de ratas injetadas com solução salina durante a gestação (n=8) e 2) Paralisia cerebral - filhotes de ratas injetadas com Lipopolissacarídeo (LPS) durante a gestação (n=8), submetidos à anóxia perinatal e restrição sensório-motora durante 30 dias. A memória espacial dos animais foi avaliada pela tarefa de reconhecimento da localização de objetos, enquanto o comportamento do tipo ansioso foi verificado pelo teste de labirinto em cruz elevado. Após a avaliação comportamental, os animais foram eutanasiados e os encéfalos dissecados para posterior processamento histológico. RESULTADOS: O grupo PC apresentou déficits de memória espacial e uma redução do número de neurônios granulares no giro denteado. Entretanto o comportamento do tipo ansioso e a histologia do núcleo central e complexo basolateral da amígdala foram semelhantes entre os grupos. CONCLUSÃO: Como observado em parte dos pacientes com PC, este modelo experimental prejudica a memória dependente do hipocampo. Entretanto, a combinação de intervenções não alterou a ansiedade e estrutura da amígdala.

BASIS: Cerebral palsy (CP) is a disorder of movement and posture, which may be associated with cognitive impairments. Such clinical condition is caused by non progressive injuries ocurred during the brain development. In the experimental context, animal models of this condition that can reproduce the phenotype and the structural changes seen in humans are scarce. OBJECTIVE: The present study investigated cognitive function and hippocampus and amygdala structure in rats submitted to a CP model. METHODS: Two experimental groups were used: 1) Control - offspring of rats injected with saline during pregnancy (n = 8) and 2) Cerebral Palsy - offspring of rats injected with lipopolysaccharide (LPS) during pregnancy (n = 8), submitted to perinatal anoxia and sensorimotor restriction for 30 days. The spatial memory was evaluated by the object-placement recog- nition task and anxiety like-behavior by elevated plus maze test. After the behavioral assessment, animals were euthanized and brains dissected for histological processing. RESULTS: The PC group showed spatial memory deficits and a reduction of granule neurons in the dentate gyrus. However, the anxiety like-behavior and the number of neurons in central nucleus and basolateral complex of the amygdala were similar between studied groups. CONCLUSION: This animal model affects the hippocampus dependent memory, a deficit seen in part of CP patients. However, the interventions used did not alter the anxiety like-behavior and amygdala structure.