Binding of [³H]-Dopamine to Human Lymphocytes: Possible Relationship to Neurotransmitter Uptake Sites

Abstract

Freshly isolated human lymphocytes from 11 healthy subjects had specific binding sites for dopamine which were dependent on time, temperature and sodium, and appeared to follow Michaelis-Menten kinetics. The apparent affinity constant (K_D) of human lymphocytes for dopamine and the maximal number of binding sites (B_max) were 109 ± 21 nM and 2.66 ± 1.75 pmol/107 cells, respectively. Dopamine binding was markedly affected by cocaine (IC50 = 150 nM) and other inhibitors of biogenic amine uptake. The relatively high potency of cocaine in competing for dopamine binding suggested that human lymphocytes may serve as a readily accessible model to detect changes in the neuronal uptake of dopamine and perhaps other monoamine neurotransmitters.

Correlation between cortisol level and serotonin uptake in patients with chronic stress and depression

“…This effect was associated with the GR-cortisol complex, which regulates transcriptional responses upon binding to a hormone response element, located in the promoter region of the target genes (Reichel & Jacob, 1993). The gene encoding the human serotonin transporter was shown to be identical in neurons and lymphocytes (Faraj et al, 1994(Faraj et al, , 1997, and various studies indicate that the analogy in the uptake of neurotransmitters between both types of cells is actually valid (Faraj et al, 1991(Faraj et al, , 1994(Faraj et al, , 1997Grodzicki et al, 1990;Halbach & Henning, 1989). In addition, we also reported that PBLs from rabbits previously treated in vivo with cortisol presented an effect similar to that observed in human PBLs upon incubation with cortisol in vitro.…”

“…Uptake of serotonin (5-HT) was assayed with tritiated 5-HT ([ 3 H]-5-HT, NEN) essentially as reported in Faraj et al (1991Faraj et al ( , 1994. Cortisol-treated and control samples were incubated for 15 min at 37º C in the presence of 10 -6 M 5-HT (Sigma), doped with [ 3 H]-5-HT in 1.5-ml microtubes (Eppendorf ).…”

Presence and Characterization of the Serotonin Transporter in Human Resting Lymphocytes

“…The pharmacological profile overlapped with that obtained by our group in brain and platelet membranes (Rotondo et al 1996): in fact, the different compounds showed the same rank of potency in all these tissues. The lack of activity of mazindol and nomifensine at the level of [ 3 H]PAR binding shows that we were not labeling the dopamine transporter, which is present at a high concentration in lymphocytes (Faraj et al 1991). The presence of the 5-HT transporter in human lymphocytes suggests its possible role in some immune functions, mediated by these cells and by 5-HT, whose role as an immunomodulator is currently emerging (Fillion et al 1996).…”

Catecholamines—Crafty Weapons in the Inflammatory Arsenal of Immune/Inflammatory Cells or Opening Pandora’s Box?

“…Human lymphocytes also have been shown to express some of these reuptake transporters. Dopaminespecific binding sites, as well as a dopamine-selective reuptake system, have been demonstrated on human lymphocyte membranes (35,36). Selective blockade of these monoamine transporters suppressed both the dopamine binding to the specific sites and the uptake of [ 3 H]-dopamine.…”