Investigating the effects of different exercise protocols on depressive-like behaviors and brain-derived neurotrophic...

Depression is one of the most common and important mental disorders worldwide. On the other hand, different protocols of exercise may affect the depressive state. Brain-derived neurotrophic factor (BDNF), as the most important neurotrophic factor in the brain, also plays a role in mood modulation. In this systematic study, the effects of different exercise protocols on Bdnf expression and BDNF protein levels and depressive-like behaviors in rodents were investigated. In the initial search in PubMed database, 226 articles were identified. After removing duplicates, 108 articles remained. 18 articles were excluded due to unavailability of full text. In the next step, 4 articles were excluded (n = 1 review article, n = 2 clinical study, and n = 1 non-English article). Finally, 31 articles were found that were not related to depression, exercise, and BDNF. As a result, 55 articles were included. The results showed conflicting reports. We showed decreases, increases, or no changes in BDNF levels after different protocols of exercise, with or without antidepressant effects. Studies in females were very limited. Regarding brain regions, most studies focused on the hippocampus. In conclusion, we recommend that future studies should focus specifically on females to determine whether there are significant differences in their response to exercise. Examining other brain regions would also be valuable for future research. BDNF assays, such as ELISA and Western blot, are the most commonly used techniques; however, the findings obtained using these methods have been inconsistent across studies. Therefore, future studies should employ standardized and well-validated approaches for BDNF assessment to improve comparability and help clarify the relationship between exercise, BDNF regulation, and depressive-like behaviors.