Evidence of the involvement of the monoaminergic systems in the antidepressant-like effect of Aloysia gratissima

Abstract

Ethnopharmacological relevance: Aloysia gratissima (Verbenaceae) is an aromatic plant distributed in South America and, employed in folk medicine for the treatment of nervous systems illness, including depression. The neuroprotective and antidepressant-like activities of the aqueous extract of Aloysia gratissima (AE) administered orally has already been demonstrated.In this study the involvement of monoaminergic systems in the antidepressant-like effect of the AE was investigated.

Materials and methods: The implication of the monoaminergic systems in the antidepressant-like activity of Aloysia gratissima was evaluated using different pharmacological antagonists that were administered previously to the acute oral administration of AE (10 mg/kg). The antidepressant-like effect was assessed in the TST and locomotor activity was evaluated in the open-field test in mice.

Results: The anti-immobility effect elicited by AE in the TST was prevented by the pre-treatment of mice with the antagonists, NAN-190 (5-HT(1A) receptor), ketanserin (5-HT(2A/2C) receptor), prazosin (α1-adrenoceptor), yohimbine (α2-adrenoceptor), SCH23390 (dopamine D1 receptor), or sulpiride (dopamine D2 receptor).

Conclusions: These results indicate that the antidepressant-like effect of AE in the TST is dependent on its interaction with the serotonergic (5-HT(1A) and 5-HT(2A/2C)), noradrenergic (α1 and α2-adrenoceptors) and dopaminergic (D1 and D2 receptors) systems, suggesting that this specie might act as a new potential resource for developing antidepressants to treat depressive disorders.

Keywords: Aloysia gratissima; Antidepressant-like effect; Tail suspension test.