Antidepressant-like effect of the ethanolic extract from Suanzaorenhehuan Formula in mice models of depression

Suanzaorenhehuan Formula (SHF) is a Chinese herbal formula for the treatment of depression-like disorders. It contains four herbs: Semen Ziziphi spinosae, Cortex Albiziae, Radix Paeoniae Alba and Semen Platycladi. The present study is to investigate the antidepressant-like effect of the ethanolic extract of SHF and its possible mechanisms. Mouse models of depression including the tail suspension test (TST), forced swimming test (FST) and chronic unpredicted mild stress (CUMS) were used to evaluate the effects of SHF extract. The mechanisms were examined by measuring monoamine neurotransmitters in mice hippocampus and frontal cortex, testing monoamine oxidase enzyme (MAO) activities in brain of CUMS-exposed mice. After one-week treatment, SHF extract (50, 100 and 200mg/kg) induced a significant decrease on immobility time in TST. After two-week treatment, SHF extract (50, 100 and 200mg/kg) led to a reduction in the immobility period in TST and FST. The 5-HT levels in mice hippocampus were increased only after 200mg/kg SHF extract treatment. The noradrenaline (NE) levels were increased after 200mg/kg SHF extract treatment in mice hippocampus and frontal cortex. SHF extract (50, 100 and 200mg/kg) significantly inhibited monoamine oxidase-A (MAO-A) and monoamine oxidase-B (MAO-B) after 21-day CUMS exposure. These findings demonstrated that ethanolic SHF extract produced an antidepressant-like effect and the mechanism of action involves the serotonergic, noradrenergic and monoamine oxidase enzyme systems although underlying mechanism still remains to be further elucidated.