Fluoxetine: a review of receptor and functional effects and their clinical implications.

Downregulation of serotonin 5-HT1 receptors is the most frequently reported central nervous system neural effect of subchronic exposure to fluoxetine in rodents. However, downregulation of these receptors has not been universally demonstrated. Effects of subchronic exposure on 5-HT2 receptors are mixed. Fluoxetine exposure appears to have no effect on cholinergic muscarinic receptors. Effects on beta-adrenergic receptors are controversial, as only one laboratory has reported downregulation. The majority of studies have failed to show an effect on beta-adrenergic-receptor-stimulated cAMP generation. Electrophysiologic studies support the concept that fluoxetine facilitates net serotonergic transmission through downregulation of presynaptic inhibitory autoreceptors. Data suggest that its subchronic specificity and selectivity distinguish fluoxetine from members of other classes of available antidepressants, making it a distinct therapeutic option.