ACTIVE [H-3] DOPAMINE UPTAKE BY HUMAN-LYMPHOCYTES - CORRELATES WITH SEROTONIN TRANSPORTER ACTIVITY

The main objective of the present investigation was to determine wheth er the uptake ofH-3-dopamine in human lymphocytes is mediated throug h a serotonin transporter. This was examined by studying the effects o f various monoamine uptake inhibitors on the uptake of H-3-dopamine in human lymphocytes. Among the compounds tested, indatraline, imipram ine and fluoxetine, selective inhibitors of neuronal serotonin transpo rter, were the most potent inhibitors of H-3, dopamine uptake in lym phocytes. The 50% inhibiting concentration (IC50) for these inhibitors was in the range of 3.5-17 nmol/l. Bupropion, GBR 12909, nomifensine and xylamine, selective inhibitors of dopamine and norepinephrine tran sporters, had low affinity for the dopamine uptake system in human lym phocytes with IC50 values ranging between 1,000 and 40,000 nmol/l. The se findings provide supportive evidence for the participation of a ser otonin transporter in the uptake of H-3-dopamine in human lymphocyte s. The existence of a high affinity transport system for dopamine and serotonin in human lymphocytes may serve as a readily accessible model to detect changes in the neuronal uptake of dopamine and serotonin in addictive and psychiatric disorders.