Mechanisms Underlying Exercise-Induced BDNF Stimulated Memory Improvements in Rodents

Abstract

Introduction: Increases in Brain-Derived Neurotrophic Factor (BDNF), are known to be associated with improvements in memory and can be increased by exercise. This suggests that these memory improvements could be induced from exercise associated increases in BDNF in key memory related areas of the brain such as the hippocampus. However, the underlying neurobiology outlining how exercise may affect memory remains elusive. Thus, the focus of this review is to understand the relationship between exercise induced increases in BDNF and memory improvements, and to identify potential pathways of activation that may induce these effects. Methods: An in-depth literature review was performed to analyze the mechanisms of memory involving exercise induced increases of BDNF in rodents. Both primary and review articles were used, found through Google Scholar, PubMed, and the George Washington University Gelman Library databases, and were found using search terms that included exercise, memory, rodents, and BDNF. Results: Pathways found to be potentially involved in this mechanism include the TrkB ERK1 pathway, TrkB activation of β-CaMKII, PI3-K and MAPK pathways, and the BDNF/TrkB/SYN pathway, with the SIRT1/PGC1a/FNDC5 pathway being a potential upstream pathway to induce BDNF activity. It was also found that exercise induced BDNF increases can recover memory impairments in different neurodegenerative states, such as in rodent models of Alzheimer’s disease and Down syndrome. Discussion: The collected studies demonstrate that exercise induced increases in BDNF expression are related to improved memory at least partially due to increased BDNF expression in memory associated brain regions, such as the hippocampus. The underlying neurobiology is still unclear, although potential pathways for this mechanism have been identified. Conclusion: These results of this review expose avenues of research to better understand the underlying neurobiology of exercise enhanced BDNF effects on memory improvements. The identified link between exercise and memory improvements via exercise induced BDNF increases can be potentially applied and used for future investigations into clinical therapeutic treatments for improving memory through exercise.