Exercise Maintains Dendritic Complexity in an Animal Model of Posttraumatic Stress Disorder.

Introduction: This study examined the effect of endurance exercise on dendritic arborization in the dentate gyrus subregion in rodents exposed to a predator scent stress (PSS).

Methods: Sprague-Dawley rats were randomly assigned to one of four treatment groups. In two of the groups, rats were unexposed to PSS but either remained sedentary (SED + UNEXP) or were exercised (EX + UNEXP). In the other two groups, rats were exposed to the PSS but either remained sedentary (SED + PSS) or were exercised (EX + PSS). After 6 wk of either exercise or sedentary lifestyle, rats were exposed to either the PSS or a sham protocol. During exercise, the animals ran on a treadmill at 15 m·min, 5 min·d gradually increasing to 20 min·d, 5 d·wk for 6 wk. Eight days after exposure to either PSS or sham protocol, changes in the cytoarchitecture (dendritic number, dendritic length, and dendrite spine density) of the dentate gyrus subregion of the hippocampus were assessed.

Results: No differences (P = 0.493) were noted in dendritic number between the groups. However, dendritic length and dendrite spine density for SED + PSS was significantly smaller (P < 0.001) than that observed in all other groups. In addition, neurons from animals in SED + PSS had significantly fewer (P < 0.001) dendritic intersections than all other groups.

Conclusion: The results of this study indicate that 6 wk of endurance training can protect dendritic length and complexity, suggesting a degree of resiliency to stress. This provides further evidence for supporting the inclusion of an exercise regimen for reducing the risk of posttraumatic stress disorder.