Antidepressant-like effect of flavonoids extracted from Apocynum venetum leaves on brain monoamine levels and dopaminergic system

Ethnopharmacological relevance: Apocynum venetum L. (Apocynaceae), a traditional medicinal plant, has been used for the improvement of emotions in Asian countries. Aim of the study: We explored the antidepressant-like effect and monoaminergic mechanism of a flavonoids extract from Apocynum venetum leaves (AV-extract). Materials and methods: Effect of AV-extract (25, 50 and 100 mg/kg, i.g.) on mice's immobility time was assessed in forced swim test (FST) and tail suspension test (TST). The locomotor activity was evaluated in the open-field test (OFT). Additionally, the main monoamine neurotransmitters serotonin (5-HT), noradrenaline (NA) and dopamine (DA) and their metabolites 5-hydroxyindole-3-acetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the mouse hippocampus involved in the antidepressant-like effect of AV-extract was also determined by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). Results: AV-extract (50 and 100 mg/kg, i.g.) administration significantly reduced the immobility time in both the FST and TST without accompanying changes in locomotor activity in the OFT. It was also found that the AV-extract significantly increased the concentrations of the main neurotransmitters NE and DA along with their respective metabolites DOPAC, HVA in the hippocampus. The antidepressant-like effect of the AV-extract (50 mg/kg, i.g.) was prevented by the pretreatment of mice with SCH23390 (0.05 mg/kg, i.g., a dopamine D-1 receptor antagonist) or sulpiride (50 mg/kg, i.g., a dopamine D-2 receptor antagonist). Conclusion: The AV-extract produced significant antidepressant-like effects, which likely attribute to increased NE and DA along with their respective metabolites DOPAC, HVA in the mouse hippocampus, and dependent on interaction with dopaminergic (D-1 and D-2 receptor) systems. (C) 2013 Elsevier Ireland Ltd. All rights reserved.