Antidepressant-like activity of methyl jasmonate involves modulation of monoaminergic pathways in mice.

Purpose: The efficacy of current antidepressant drugs has been compromised by adverse effects, low remission and delay onset of action necessitating the search for alternative agents. Methyl jasmonate (MJ), a bioactive compound isolated from Jasminum grandiflorum has been shown to demonstrate antidepressant activity but its mechanism of action remains unknown. Thus, the role of monoaminergic systems in the antidepression-like activity of MJ was investigated in this study.

Materials And Methods: Mice were given i.p. injection of MJ (5, 10 and 20mg/kg), imipramine (10mg/kg) and vehicle (10mL/kg) 30min before the forced swim test (FST) and tail suspension test (TST) were carried out. The involvement of monoaminergic systems in the anti-depressant-like effect of MJ (20mg/kg) was evaluated using p-chlorophenylalanine (pCPA), metergoline, yohimbine, prazosin, sulpiride and haloperidol in the TST.

Results: MJ significantly decrease the duration of immobility in the FST and TST relative to control suggesting antidepressant-like property. However, pretreatment with yohimbine (1mg/kg, i.p., an α-adrenergic receptor antagonist) or prazosin (62.5μg/kg, i.p., an α-adrenoceptor antagonist) attenuated the antidepressant-like activity of MJ. Also, pCPA; an inhibitor of serotonin biosynthesis (100mg/kg, i.p) or metergoline (4mg/kg, i.p., 5-HT receptor antagonist) reversed the anti-immobility effect of MJ. Sulpiride (50mg/kg, i.p., a D receptor antagonist) or haloperidol (0.2mg/kg, i.p., a dopamine receptor antagonist) reversed the anti-immobility effect of MJ.

Conclusion: The results of this study suggest that serotonergic, noradrenergic and dopaminergic systems may play a role in the antidepressant-like activity of MJ.