Antidepressant-like effects of Foeniculum vulgare essential oil and potential involvement of dopaminergic and serotonergic systems on mice in the forced swim test

Abstract

BackgroundFennel (Foeniculum vulgare) is widely used in food and pharmaceutical industries. Animal models also showed the antidepressant-like effect of the methanolic extract of fennel. Accordingly, the antidepressant potential of Foeniculum vulgare essential oil (FVEO) and the contribution of monoaminergic systems to this effect were evaluated in mice using the forced swim test (FST). MethodsThe albino mice (22−27 g) received vehicle (10 mL/kg, i.p.), fluoxetine (20 mg/kg, i.p.), imipramine (30 mg/kg, i.p.), and FVEO (50−400 mg/kg, i.p.) and then underwent FST. Different noradrenergic, dopaminergic and serotonergic receptor antagonists were used to determine the contribution of monoaminergic systems. ResultsDifferent doses of FVEO (100−400 mg/kg; p < 0.01, p < 0.001 and p < 0.001, respectively) induced antidepressant-like effects in FST without any alterations in animal locomotion in the open-field test (p > 0.05). Concurrent use of a non-effective dose of FVEO (50 mg/kg) and imipramine or fluoxetine (5 mg/kg) caused synergistic antidepressant-like effects (P < 0.001). The antidepressant-like effects of FVEO were blocked through pretreating the mice with sulpiride (P < 0.001), haloperidol (P < 0.001), ritanserin (P < 0.001), SCH-23390 (P < 0.001), WAY-100635 (P < 0.001) and p-chlorophenylalanine (P < 0.001); however, prazosin and yohimbine were not effective (P > 0.05). ConclusionsThe present findings attributed the antidepressant-like effects of FVEO, at least partly, to dopaminergic and serotonergic systems, but not to noradrenergic system.