Behavioural and neurochemical characterisation of the anxiolytic properties of an aqueous extract of Dysphania ambrosioides (L.) Mosyakin and Clemants (Chenopodiaceae) in experimental mice

Ethnopharmacological relevance: Dysphania ambrosioides (L.) Mosyakin & Clemants (Chenopodiaceae) is a medicinal plant known for its anxiolytic, antidepressant and anticonvulsant activities in Cameroonian folk medicine. Aim of the study: The aim of this work is to evaluate the anxiolytic effects of Dysphania ambrosioides aqueous extracts and investigate its mechanism of action. Materials and methods: Elevated plus maze test and open field test were used for detecting it anxiolytic properties. The possible mechanism of action of the aqueous extracts were investigated after pretreatment of animals with different antagonists of GABAA complex receptors (5 mg/kg N-methyl-β-carboline-3-carboxamide, 4 mg/kg flumazenil or 2 mg/kg bicuculline) 30 minutes prior to the oral administration of 370 mg/kg Dysphania ambrosioides aqueous extract. Results: Dysphania ambrosioides increased the percentage of entries into and percentage of time in open arms, and reduced rearing, head dipping, and percentage of time in closed arms, in the elevated plus maze. It reduced rearing and defecation, and increased crossing, in the open field. In addition, anxiolytic-like properties of Dysphania ambrosioides were blocked by different antagonists of GABAA complex receptors (N-methyl-β-carboline-3-carboxamide, flumazenil or bicuculline) as examined in elevated plus maze test. Finally, the activity of GABA-T activity was inhibited and the brain GABA concentration was increased by the extracts, respectively. Conclusion: These results suggest that Dysphania ambrosioides possess anxiolytic-like properties in mice that might involve an action on benzodiazepine and/or GABA sites in the GABAA receptor complex or by modulating brain GABA concentration in the central nervous system.