What does an SSRI actually block? · Grey Matter

A selective serotonin reuptake inhibitor binds the serotonin transporter (SERT), the protein on serotonin terminals that pulls released serotonin back into the cell.

What does an SSRI actually block?

A selective serotonin reuptake inhibitor binds the serotonin transporter (SERT), the protein on serotonin terminals that pulls released serotonin back into the cell. With SERT blocked, serotonin stays longer in the extracellular space and reaches receptors farther from its release sites. Selective means it spares the dopamine and noradrenaline transporters that older tricyclic antidepressants also hit, which reduces side effects. The serotonin rise is immediate, while the clinical effect on depression takes weeks, so the drug's action begins at the transporter but its benefit depends on slower adaptations.