Effects of preconditioning or following exercise on brain-derived neurotrophic factor (BDNF): A systematic review in animal models of multiple sclerosis

Brain-derived neurotrophic factor (BDNF) plays a vital role in the brain. On the other hand, researchers showed that exercise may cause more release of BDNF and thus have a positive effect on the brain. Studies have reported controversial findings in multiple sclerosis, and there are no broad conclusions on this topic. This study aims to systematically investigate the effect of exercise training on BDNF concentration in multiple sclerosis animal models. Searches were conducted in the electronic databases of PubMed, Scopus, Medline, Cochrane Library and Google Scholar search engine to obtain the related articles about the role of exercise training on BDNF levels just in animal models of multiple sclerosis. All of the database searches were limited to the period from inception to February 2021. Two reviewers extracted study details and data. The methodological quality of the studies that used animal models was assessed using the PEDro Scale. Fourteen articles were included in this review with scores from 7/10 to 8/10 according to the PEDro scale. Five articles reported elevation, one article reported a reduction; and eight articles reported no changes in BDNF level following or preconditioning exercise training in model of multiple sclerosis. The findings of this study showed that aerobic exercise increases changes in central BDNF concentration in multiple sclerosis in animal model.