Antidepressant evaluation of polysaccharides from a Chinese herbal medicine Banxia-houpu decoction

Banxia-houpu decoction, a traditional Chinese medicine has been used in the treatment of depression. The present study confirmed that oral administration of polysaccharides from Banxia-houpu decoction, exhibited a reduction in the immobility time in the tail suspension and in the forced swimming tests in mice in a time-dependent manner. This effect at a dose of 320 mg/kg was more potent than that at a dose of 640 mg/kg. The polysaccharides from Banxia-houpu decoction were active in animal models of depression with comparable effects to known antidepressants. The oral administration of the polysaccharides at a low dose for 4 weeks resulted in a significant increase in the monoamine neurotransmitter 5-hydroxytryptamine (5-HT) and dopamine (DA) levels in whole mouse brain, but produced no significant increase in 5-hydroxyindoleacetic acid (5-HIAA) and norepinephrine (NE) concentrations. The effect of polysaccharides on the brain neurotransmitter levels appeared to be quite different from the effect of fluoxetine, a serotonin specific reuptake inhibitor. The results indicate that the mode of action of polysaccharides from Banxia-houpu decoction in depression might be related to both 5-HT and DA systems.