Major depressive disorder (MDD) is a multifactorial disease including the abnormalities of monoaminergic neuronal system. At present, MDD is a public health problem nationwide and worldwide, which enormously leads to the quality of life of patients and their families. MDD patients have to be treated for a long period using anti-depressants, which are not only expensive, but cause unfavorable side effects and ineffective. Therefore, our research group has attempted to study potential anti-depressants with low side effects, high efficiency and reasonable price. In this study, we investigated the mechanisms of action of medicinal extracts, leaves of Mentha cordifolia Opiz ex Fresen and Senna siamea (Lam.) and whole plants of Centella asiatica (Lam.), using LAN-5 neuroblastoma cell line as a model. Extractions were done using ethanol and water. We focused our study on inhibitory effects of herb extracts on two mechanisms, mRNA expression of human dopamine transporter (hDAT), human serotonin transporter (hSERT) and human norepinephrine transporter (hNET) and activity of all three neurotransmitter transporters by uptake assay using neurotransmitter transporter uptake assay kit with the utilization of fluoxetine, desipramine and GBR12935 as the reference drugs. In addition, MTT assay was employed for toxicity study. We discovered that all of the extracts significantly reduced the expression of hDAT, hSERT and hNET genes in LAN-5 (P<0.05). The extract derived from M. cordifolia significantly inhibited the activity of DAT and SERT in LAN-5 (P<0.05) and all of extracts were not toxic to LAN-5.
