Carrier-mediated serotonin release induced by d-fenfluramine: studies with human neuroblastoma cells transfected with a rat serotonin transporter.
The NMB human neuronal cell line, transfected with a newly prepared plasmid expressing rat serotonin transporter (NMB-rSERT), shows specific [3H]5-HT uptake which is blocked by citalopram and fenfluramine (F) stereoisomers with IC50 values (1 nM. 0.5 microM (dF) and and 5 microM (IF), respectively) which are similar to those found in rat brain synaptosomes. d-Fenfluramine (0.5 and 10 microM) also stimulates tritium release from NMB-rSERT cells preloaded with [3H-]-5-HT. The d-fenfluramine-induced [3H-]5-HT release is blocked by 0.3 microM citalopram and is dependent on the density of SERT expressed per cell, but is not affected by removal of Ca++ ions from the incubation medium. Manipulation of the Na+ gradient across the plasma membrane (replacing 60 mM NaCl with an equimolar concentration of KCl or choline) also induced [3H-]5-HT release from NMB-rSERT cells, which was inhibited by 0.3 microM citalopram. These results, together with the finding that NMB-rSERT cells preloaded with 500 nM unlabelled 5-HT take up [3H-]d-fenfluramine, make NMB-rSERT cells a valuable tool for studying the transporter-mediated exchange release induced by amphetamine derivatives.
Cinquanta
M
M
Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Ratovitski
T
T
Crespi
D
D
Gobbi
M
M
Mennini
T
T
Simantov
R
R
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics*; D015283:Citalopram / Q000494:pharmacology; D005277:Fenfluramine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured
D002118:Calcium; D002352:Carrier Proteins; D015283:Citalopram; D005277:Fenfluramine; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011188:Potassium; D012701:Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors; C493230:SLC6A4 protein, human; C493232:Slc6a4 protein, rat