Cellular localization and expression of the serotonin transporter in mouse brain

The high-affinity serotonin (5-HT) transporter (5-HTT) plays an important role in the removal of extracellular serotonin, thereby modulating and terminating the action of this neurotransmitter at various pre-and post-synaptic serotonergic receptors and heteroreceptors. In order to characterize the anatomical distribution of the 5-HTT in mouse brain, in situ hybridization histochemistry using ?S-35-labeled riboprobes was performed. These results were compared with 5-HTT binding site distribution as evaluated by [I-125]RTI-55 autoradiography. High levels of 5-HTT mRNA were detected in all brain stem raphe nuclei, with variations in labeling among the various subnuclei. Those bl ain arena known; to possess serotonergic cell bodies stained intensely for both 5-HTT mRNA and 5-HTT binding sites. In contrast to previous findings in rat brain, the highest densities of 5-HTT sites were found in areas outside the raphe complex, particularly in the substantia nigra, globus pallidus, and superior colliculi. (C) 1997 Elsevier Science B.V.