 The majority of the TCAs act primarily as SNRIs by blocking the serotonin transporter (SERT) and the norepinephrine transporter (NET), which results in an elevation of the synaptic concentrations of these neurotransmitters, and therefore an enhancement of neurotransmission.Notably, with the sole exception of amineptine, the TCAs have negligible affinity for the dopamine transporter (DAT), and therefore have no efficacy as dopamine reuptake inhibitors (DRIs).Both serotonin and norepinephrine have been highly implicated in depression and anxiety, and it has been shown that facilitation of their activity has beneficial effects on these mental disorders.