Flavangenol, a pine bark extract rich in polyphenols, has been shown to exhibit antioxidative stress properties. Moreover, it is well known that increased oxidative stress is linked with mental stress. Therefore, we hypothesized that flavangenol may offer some beneficial effects to mice under stressful conditions. A high level of flavangenol (600 mg/10 ml/kg body weight) was administered daily to mice by gavage with or without unpredictable chronic mild stress (through daily exposure to different stressors) for 35 days. It was found that the stressors applied in this experiment greatly increased the amount of stress experienced by the mice, as evidenced by the reduction in body weight, in the distance traveled in the inner area in the open field test, in the concentration of brain-derived neurotrophic factor in the hippocampus, and by the increase in the concentration of norepinephrine (NE), epinephrine and dopamine (DA) in the plasma. However, the mice seemed not to be in a depressive state, since the result of the sucrose preference test was not significantly different from the result for the control. On the other hand, the administration of a chronically high level of flavangenol was needed to attenuate the stress, as shown by plasma corticosterone concentrations and the decrease in the plasma concentrations of DA and NE. In the non-stressed mice, an unpredicted effect of flavangenol was observed, whereby the distance traveled in the inner area in the open field test decreased. In conclusion, chronic effects resulting from a high level of flavangenol may depend on the particular state of stress, and taking flavangenol may be merited for animals suffering as a result of a stressor.
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