The effects of chronic and acute physical and psychological Stress on Brain- Derived Neurotrophic Factor in Rats

Different kinds of chronic stress can induce various effects on body systems including the brain. One of the factors related to brain function is brain derived neurotropic factor (BDNF). So, the purpose of the present study was to evaluate the influence of physical stress as aerobic exercise/training and psychological stress on brain derived neurotropic factor (BDNF) in Wistar rats.

The study was semi experimental.  90 healthy male Wistar rats (weight 200±40 gr) were randomly divided in to 6 groups of Exercise (EX), Emotional stress (ES), Physical stress (PS), exercise combined with emotional (EXES), exercise combined with physical stress (EXPS) and control. Wistar rats were exposed to programs included one session (acute) and two weeks (chronic) aerobic training on treadmill with or without emotional and physical stress. Blood samples, for BDNF measurement, were taken 12 hours following the last session of treatment.  Statistical tests of analysis of variance and follow up Bonferroni test were used for data analysis.

After one session of the experiment, BDNF increased significantly in the EX group compared to other groups (p<0.05). After two weeks of training, BDNF significantly decreased in the ES groups compared to other groups, while BDNF increased in EXES compared to ES (P<0.05) group. One session of EX increased BDNF compared to non-EX groups, but following two weeks, chronic ES per se reduced BDNF compared to non-ES groups. But when ES combined with EX caused increasing of BDNF.

Present findings suggest that EX can probably prevent decreasing effect of ES on BDNF. However, future research should clarify the source of BDNF changes.