Effect of aqueous extract and fractions of Zhi-Zi-Hou-Pu decoction against depression in inescapable stressed mice: Restoration of monoamine neurotransmitters in discrete brain regions

Context: Zhi-Zi-Hou-Pu decoction (ZZHPD) is a traditional prescription which has been used to treat Yu-syndrome (depression and melancholia) in Chinese herbal medication. Objective: To evaluate antidepressant activities of ZZHPD, its fractions and possible mechanism(s) of action. Materials and methods: ZZHPD (1241, 2482 and 4964 mg/kg), n-butanol fraction (ZH-BA, 1454 mg/kg), cyclohexane fraction (ZH-CH, 17 mg/kg) and aqueous fraction (ZH-AQ, 3493 mg/kg) were administered orally to different groups of mice for seven consecutive days. Forced Swimming Test (FST) and Tail Suspension Test (TST) were conducted 60 min after the last administration to evaluate the antidepressant effect. Norepinephrine, dopamine and 5-hydroxytryptamine levels in discrete brain parts were determined by HPLC-FD immediately after behavioral tests. Results: ZZHPD at 2482, 4964 mg/kg, ZH-BA (1454 mg/kg), ZH-CH (17 mg/kg) or clomipramine hydrochloride (20 mg/kg) significantly (p < 0.05) reduced the duration of immobility in FST and TST without affecting locomotor activities in the Open Field Test. Observed from score plot of Principle Component Analysis of monoamine levels in different groups, the monoamine profile of ZZHPD-treated mice were similar to that of the normal control mice. HPLC-UV analysis indicated that iridoid glycosides, flavones and neolignans might be the active chemicals. Discussion and conclusion: The results demonstrated significant antidepressant-like effect of ZZHPD in mice which was related to monoaminergic system, ZH-BA and ZH-CH could be the active fractions responsible for the antidepressant effect of ZZHPD.