Efficacy of different intensity of aquatic exercise in enhancing remyelination and neuronal plasticity using cuprizone model in male Wistar rats

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS). Most exercise studies concentrate on the impact of exercise on cardiovascular system; this study aims to present the effects of exercise of varying intensity on the nervous system. Most recently in MS, positive outcomes were obtained with resistance and high-intensity exercises. This study also analyzes the effects of a prior conditioning program before the induction of demyelination and subsequent neuroprotective effects of such program.To study and determine the neuroprotective and remyelinating effects of different intensity of aquatic exercise and a preconditioning exercise program on demyelination induced by oral administration of cuprizone (Cup).Six groups of animals, each containing 6 rats, were used in the study. The groups were as follows: group I - control group; group II - Cup group; group III - treated with methylprednisolone (MP); group IV - treated with low-intensity exercise (LIE), free swimming for 40 min and high-intensity exercise (HIE); group V - treated with a resistance of 9% body weight and free swimming for 40 min; group VI - treated with preconditioning exercise (free swimming for 40 min for 3 weeks) before Cup administration followed by the same exercise protocol as for group V. All data were analyzed using one-way analysis of variance (ANOVA) with Tukey's test, by means of SigmaPlot v. 14.5 software.Similarly to the MP group, group VI showed a positive outcome. A value of p < 0.001 was considered statistically significant. Also, group VI showed improved areas of remyelination in histopathology, an increased expression of myelin basic protein (MBP), reduced expression of glial fibrillary acidic protein (GFAP) in corpus callosum, and improved gene expression of brain-derived neurotrophic factor (BDNF) in the hippocampus region.General fitness achieved through a preconditioning program combined with HIE showed neuroprotective effects, as evidenced by increased areas of remyelination and improved neuronal plasticity, observed mostly in group VI (conditioning+HIE).