Involvement of the catecholaminergic system on the antidepressant-like effects of Alpinia zerumbet in mice.

BACKGROUND

The traditional uses of Alpinia zerumbet (Pers.) B.L.Burtt & R.m.SM (Zingiberaceae), popularly known as colonia or pacová, suggest that the species has antihypertensive, diuretic, and sedative properties. We previously reported that an ethanol extract of Alpinia zerumbet (HEA) significantly reduced the immobility time in the tail suspension test (TST), similar to the tricyclic antidepressant imipramine. Moreover, HEA presented antioxidant and anxiolytic-like effects in mice.

OBJECTIVE

The objective of this study is to investigate the involvement of monoaminergic and glutamatergic systems in the antidepressant-like effects of this species.

METHODS

A hydroethanolic extract prepared with the leaves of A. zerumbet was assayed in the TST in male Swiss mice (800 mg/kg, p.o.). Synthesis inhibitors (AMPT, inhibitor of tyrosine hydroxylase, 100 mg/kg, i.p.; and PCPA, irreversible tryptophan hydroxylase inhibitor, 100 mg/kg, i.p.) and a specific glutamate antagonist (AMPA receptor antagonist NBQX, 10 mg/kg, i.p.) were used prior testing.

RESULTS

Pre-treatment with the noradrenergic/dopaminergic inhibitor AMPT fully abolished the anti-immobility effects of HEA, with the two-way ANOVA yielding a significant interaction between pre-treatment and treatment (F1,32 = 10.0, p < 0.01); no interaction was observed with the serotonergic inhibitor PCPA (F1,32 = 0.33, p > 0.05) or NBQX (F1,32 = 0.21, p > 0.05).

CONCLUSIONS

These results indicated that HEA most likely acts through the dopaminergic and/or noradrenergic system but not through the serotoninergic or glutamatergic systems. This study reinforces the idea that the available biodiversity in Brazil can serve as a basis for innovation in the development of new drugs.