Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and selective brain steroidogenic stimulant (SBSS) and does not appreciably inhibit norepinephrine and dopamine reuptake at therapeutic doses. It does, however, delay the reuptake of serotonin, resulting in serotonin persisting longer when it is released. Large doses in rats has been shown to induce in a significant increase in synaptic norepinephrine and dopamine.[61][62][63][64] Thus, dopamine and norepinephrine may contribute to the antidepressant action of fluoxetine in humans at supratherapeutic doses (60–80 mg) .[63][65] This effect may be mediated by 5HT2C receptors, which are inhibited by higher concentrations of fluoxetine.[66]