The Effects of High-Intensity Exercise on Anxiety-Like Behaviors, Fear Extinction, Neurotrophic Factors, and Expression of Apoptosis-Related Factors Induced by Stress in Rat Brain

Background and

Post-traumatic stress disorder (PTSD), a type of psychiatric disorder that occurs after exposure to traumatic events, is associated with anxiety and abnormality in the activity of hypothalamic-pituitary-adrenal axis and cognitive functions. Physical activity can improve symptoms of somatic and neuropsychiatric disorders; however, appropriate exercise intensity and duration are still in question. In the present study, the effects of high-intensity exercise on anxiety-like behaviors, fear extinction, serum insulin-like growth factor (IGF-1), brain-derived neurotrophic factor (BDNF), and expression of apoptosis-related genes were investigated in the prefrontal cortex of the rat PTSD model.

In this experimental study, single prolonged stress (SPS) was used to induce PTSD in adult male Wistar rats. After 10 days, the animals in the exercise groups were subjected to high-intensity treadmill exercise (20 m/min, 5 days/week) for four weeks. Next, anxiety-like behaviors and fear extinction were examined using open field and shuttle box tests, respectively. Thereafter, serum IGF-1 and brain BDNF were measured by ELISA kits; and expression of Bax, Bcl-2, and caspase-3 in the prefrontal cortex were measured by real-time PCR.

SPS rats showed increased anxiety and decreased fear extinction, serum IGF-1, and prefrontal BDNF compared to the control animals. In addition, SPS induced apoptosis by an increase in Bax and caspase-3 and a decrease in Bcl-2. High-intensity exercise reduced apoptosis and increased serum IGF-1 significantly (P<0.05).

High-intensity exercise decreases anxiety-like behaviors by increasing serum IGF-1 and inhibiting apoptosis in the prefrontal cortex of PTSD rats.