The effect of exercise on anxiety- and depression- like behavior in aged rats

INTRODUCTION: It is determined that regular aerobic exercise can affect neurogenesis that is related to the increase in learning and memory, and decrease in depression and anxiety. Some positive effects of exercise which is divided in several bouts were seen in low tolerant individuals like elderly. AIM: We aimed to investigate the effect of exercise in several bouts on anxiety and depression like behaviour observed during aging and the role of serotonin and serotonin 1A receptors. METHODS: 24 months old (aged), 6 months old (adult) female Wistar albino rats were divided into 5 groups; aged (n = 10), adults (n = 7), serotonin reuptake inhibitor (SSRI) applied (n = 10), exercised (n = 10), SSRI applied + exercised (n = 10). After exercise all groups were evaluated using the apparatus of the open field arena, elevated plus maze and forced swim test. Serum corticosterone levels, amygdala, hippocampus and prefrontal cortex cell numbers, tissue serotonin and serotonin 1A (5-HT1A) levels were assessed. Results were evaluated by one-way ANOVA, post hoc Bonferoni statistical analysis on SPSS. RESULTS: In the open field test no difference observed between locomotor activities and presence in the middle frame of groups (p> 0.05). During elevated plus maze test aged rats were observed less in the open arms of assembly compared to adults (p <0.007). The duration increased in exercise group (p <0.05) and remained unchanged in the SSRI group(p> 0.05). In the forced swim test the aged rats were more immobile according to adults (p <0.001), the immobility time were shorter in exercise group and SSRI group, no change was observed SSRI + exercise group (p <0.001). The tissue serotonin levels in amygdala and hippocampus were lower in the aged (p <0.05) and higher in SSRI + exercise group (p <0.05). There were no difference between serotonin 1A receptor levels of exercise, SSRIs and SSRI + exercise groups. The hippocampal, prefrontal cortex and the amygdala cell numbers decreased in aged (p <0.05), increased cell numbers observed in exercise, SSRIs and SSRI +exercise groups. CONCLUSION: As a result exercise in several bouts may increase the cell numbers of hippocampus, the prefrontal cortex and amygdala thus may reduce senile anxiety and depression, serotonin and serotonin 1A receptors may have role in mechanisms of depression like behavior.