Possible mechanism of the antidepressant effect of 3,6′-disinapoyl sucrose from Polygala tenuifolia Willd

Objective The present study was designed to observe the effects of 3,6′-disinapoyl sucrose (DISS), an active oligosaccharide ester component obtained from the roots of Polygala tenuifolia Willd., on behavioral and biochemical aspects of depression induced by chronic mild stress (CMS) in rats. It is the first exploration of the possible association between DISS's antidepressant-like effects and biochemical markers of depression, and involved measuring monoamine oxidase (MAO) activity, cortisol levels, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels. Methods Rats were exposed to stressor once daily for consecutive 5 weeks. DISS and a positive control drug, fluoxetine, were administered via gastric intubation to once daily for consecutive 3 weeks from the third week. Key findings The results showed that rats subjected to CMS exhibit a reduction in sucrose intake. Conversely, brain MAO-A and MAO-B activity, plasma cortisol levels, and MDA levels were increased, while SOD activity was decreased following CMS exposures. DISS significantly inhibited MAO-A and MAO-B activity and blocked plasma elevated cortisol level, an indicator of the hypothalamic-pituitary-adrenal (HPA) axis. In addition, DISS increases SOD activity, inhibits lipid peroxidation, and lessens production of MDA. Conclusion These results suggest that DISS may possess potent and rapid antidepressant properties, which are mediated via MAO, the HPA axis and oxidative systems. These antidepressant actions make DISS a potentially valuable drug for the treatment of depression.