Introduction: Anthocyanins are organic blue, violet or red dyes, related flavonoid. They are responsible for the color of flowers, fruits and leaves of the plants. They also exert strong antioxidant properties. Oxidative stress, plays a role in pathophysiology of many diseases as is Alzheimer disease, diabetes mellitus, atherosclerosis and others. Other positive effects of anthocyanins include the suppression of the synthesis of pro-inflammatory mediators or deceleration gain in mice. Probably, oxidative stress can also affect emotionality of the individual. There are studies that show anxiolytic effect of anthocyanins and increased exploratory behavior under the influence. Therefore, the aim of our study was to monitor changes in anxiety and exploratory behavior in rats after 8-week consumption of a diet enriched with anthocyanins.
Methods: Twenty Wistar rats were divided into 2 groups by random selection. The first group was consuming a diet enriched with anthocyanins (n=10) and the second one was the control group (n=10). Animals had ad libitum access to food and water for 8 weeks. After 8 weeks, the rats were tested in automated tracking home cage, Phenotyper (Noldus, Netherlands), for 23 hours. The spot light was turned on for 6 hours between 10:00 p.m. to 04:00 a.m. of local time. The base floor of the phenotyper was divided into shelter and opened zone. Opened zone was further divided into spotlight zone and dark zone. In this study, the visit frequencies into zones, moved distance and average velocity for general locomotor activity were analyzed. Additionally, the time spent in the shelter and the opened zones, especially the spotlight zone, for evaluation of the anxiety level were measured.
Results: Behavioral analysis revealed no significant differences between the analyzed groups in average speed, overall distance moved and visit frequencies in zones. The animals spent significantly more time in the opened zones when compared to the shelter zone for both CTRL and anthocyanin groups (p<0.01). Interestingly, although no difference in overall time spent in the opened zones between the groups, the rats eating anthocyanin-rich food spent significantly less time in the spotlight zone in comparison to the CTRL group (t=2.16, p<0.05).
Conclusion: Anthocyanins enriched food did not have any effect on general locomotor activity, but interestingly, it induced anxiety-like behavior. Whether anthocyanins are responsible for this change, or other factors play a role has to be evaluated by other studies.