BACKGROUND: Many studies have proven the beneficial effects of regular exercise on psychiatric conditions. This study was set to explore the therapeutic effects and the mechanisms of treadmill exercise on a time-dependent sensitization (TDS) model which is a classical animal model for mimicking posttraumatic stress disorder (PTSD).
METHODS: Forty-seven rats were randomly assigned to one of four groups: CON (control), TDS (model), EX (treadmill), or SER (sertraline). TDS model was developed to evaluate the anti-PTSD-like effects of moderate treadmill exercise with 4-week running program. High-performance liquid chromatography technology was used to determine the levels of monoamine neurotransmitters in TDS rats. The expression of key proteins in BDNF/PI3K/Akt/CREB signaling pathway were assayed by the Western blot method.
RESULTS: The TDS procedures induced behavioral deficiencies. These deficiencies were reversed by treadmill exercise. Subsequent monoamine assays revealed that the treadmill exercise significantly increased serotonin levels in the hippocampus and decreased dopamine levels in the prefrontal cortex. Data from Western blot experiment demonstrated that exercise could normalize the decreased BDNF/TrkB/pAkt/pCREB levels in the hippocampus.
CONCLUSIONS: This study deduced that treadmill exercise ameliorated contextual fear conditioning and anxiety-like behavior in TDS model. According to the study, the mechanism involved in alleviating PTSD symptoms by treadmill exercise was due to increased 5-HT levels in the hippocampus and decreased DA levels in the prefrontal cortex. It also involved the upregulation of BDNF and the related PI3K/AKT/CREB signaling pathway.