SLC6A4 and major depressive disorder: Another class of drugs that has shown efficacy in preventing migraine and treating depression are the tricyclic antidepressants (TCAs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), which can potentiate the actions of serotonin and norepinephrine action by inhibiting reuptake via their respective transporters, the serotonin transporter (SERT) and the norepinephrine transporter (NET).