Abstract
[ 3 H]8-OH-DPAT is a selective ligand for labeling 5-HT 1A receptor sites. In competition binding experiments, we found that classic biogenic amine transporter inhibitors displaced [ 3 H]8-OH-DPAT binding at its high-affinity binding sites in HeLaS3 cells. [ 125 I]RTI-55 and [ 3 H]paroxetine are known to specifically label amine transporter sites, and this was observed in our cells. Displacement studies showed that 8-OH-DPAT displayed affinity in a dose-dependent manner for the labeled amine transporter sites. These data suggest that [ 3 H]8-OH-DPAT binds to amine uptake sites in HeLaS3 cells. A variety of drugs targeting different classes of receptors did not significantly affect [ 3 H]8-OH-DPAT binding. Moreover, we determined the specific binding effects of various serotonergic ligands (i.e. [ 125 I]cyanopindolol, [ 3 H]ketanserin/[ 3 H]mesulergine, [ 3 H]GR-65630, [ 3 H]GR-113808 and [ 3 H]LSD) that specifically labeled 5-HT 1 , 5-HT 2 , 5-HT 3 , 5-HT 4 and 5-HT 5-7 receptors, respectively. It is suggested that HeLaS3 cells contain distinct types of the related to 5-HT receptor recognition binding sites. These observations could help elucidate the relevant characteristics of different types of 5-HT receptors and 5-HT membrane transporters in tumor cells and their role in tumorigenesis. © 2010 Elsevier Inc. All rights reserved.