Nociceptive and Neuronal Evaluation of the Sciatic Nerve of Wistar Rats Subjected to Compression Injury and Treated with Resistive Exercise.

Background. To investigate the climb stairs resistance exercise on nociception and axonal regeneration in the sciatic nerve of rats. Methods. 24 Wistar rats were divided: control group (CG-no injury), exercise group (EG-no injury with physical exercise), lesion group (LG-injury, but without exercise), and treated group (LEG-injury and physical exercise). LG and LEG were subjected to sciatic nerve compression with hemostat. From the 3rd day after injury began treatment with exercise, and after 22 days occurs the removal of a nerve fragment for morphological analysis. Results. Regarding allodynia, CG obtained values less than EG (p = 0.012) and larger than LG and LEG (p < 0.001). Histological results showed that CG and EG had normal appearance, as LG and LEG showed up with large amounts of inflammatory infiltration, degeneration and disruption of nerve fibers, and reduction of the myelin sheath; however LEG presented some regenerated fibers. From the morphometric data there were significant differences, for nerve fiber diameter, comparing CG with LG and LEG and comparing axon diameter and the thickness of the myelin of the CG to others. Conclusion. Climb stairs resistance exercise was not effective to speed up the regenerative process of axons.

Efeito do exercício resistido na redução do edema, nocicepção e regeneração nervosa em um modelo de compressão do nervo isquiático / Effect of resistance training on the reduction of edema, nociception, and nerve regeneration in a sciatic nerve compression model

OBJETIVOS: Analisar os efeitos do exercício físico resistido de subida em escada, sobre o edema, nocicepção e regeneração nervosa de ratos Wistar, submetidos à compressão do nervo isquiático. MÉTODOS: Foram estudados 24 ratos Wistar, divididos igualmente entre quatro grupos: Grupo Controle, Grupo Exercício, Grupo Lesão e Grupo Tratado ­ Lesão e Exercício. O Grupo Lesão e o Grupo Tratado foram submetidos à compressão do nervo isquiático com pinça hemostática por 30 segundos. A partir do terceiro dia após a lesão, iniciou-se o tratamento com exercício resistido de subida em escada para o Grupo Exercício e o Grupo Tratado. O tratamento consistiu em realizar duas séries de 10 subidas na escada, com sobrecarga de 100 gramas e intervalo de um minuto entre uma série e outra. O estudo foi conduzido por 22 dias e nesse tempo os animais foram avaliados quanto ao edema e à nocicepção. No 22º dia de pós-operatório, os animais foram anestesiados para retirada de um fragmento do nervo isquiático para análise do número de axônios e da densidade de fibras. Em seguida, ainda sob efeito da anestesia, os animais foram eutanasiados. Os nervos coletados seguiram protocolo de processamento histológico de rotina. As expressões do Fator de Crescimento Neural e do Fator de Crescimento Derivado do Cérebro foram avaliadas por Western blotting. RESULTADOS: Não houve diferença significativa entre os grupos no tamanho do edema. O Grupo Controle apresentou maior limiar nociceptivo comparado aos demais grupos. A análise morfométrica não revelou diferença significativa entre os grupos, quanto à quantidade de axônios e à densidade de fibras. A expressão do Fator de Crescimento Derivado do Cérebro foi maior no Grupo Lesão e no Grupo Tratado quando comparados ao Grupo Controle. CONCLUSÕES: O exercício físico resistido de subida em escada, nos parâmetros propostos, não foi eficaz para reduzir o edema, a nocicepção ou aumentar o número de axônios e a densidade de fibras nervosas após lesão do nervo isquiático.

AIMS: To analyze the effects of ladder-climbing resistance training exercise on edema, nociception, and regeneration of the sciatic nerve in Wistar rats subjected to sciatic nerve compression. METHODS: Twenty-four Wistar rats were divided into four groups: Control Group, Exercise Group, Injury Group, and Treated Group (injury and exercise). Injury Group and Treated Group were subjected to sciatic nerve compression with a hemostat for 30 seconds. On the third day after injury, Exercise Group and Treated Group began treatment with ladder-climbing resistance exercise. The treatment consisted in performing two series of 10 ladder climbs with a 100-gram overload and a one-minute interval between the series. The study was conducted for 22 days, during which time the animals were evaluated for edema and nociception. Twenty-two days after surgery, the animals were anesthetized for removal of a sciatic nerve fragment and analysis of the number of axons and fiber density. Thereafter, still under anesthesia, the animals were euthanized. Nerve sampling followed the routine histological processing protocol. Expressions of Neural Growth Factor and Brain-derived Neurotrophic Factor were evaluated by Western blotting. RESULTS: There was no significant difference in edema size between groups. Control Group showed the highest nociceptive threshold compared to the other groups. The morphometric analysis showed no significant difference in number of axons and fiber density between groups. The expression of Brain-derived Neurotrophic Factor was greater in the Injury Group and the Treated Group compared to the Control Group. CONCLUSIONS: The proposed ladder-climbing resistance training was not effective in reducing edema and nociception or in increasing the number of axons and fiber density after sciatic nerve injury.