High‐Affinity Uptake of [<sup>3</sup>H]Norepinephrine by Primary Astrocyte Cultures and Its Inhibition by Tricyclic Antidepressants

Kimelberg, Harold K.; Pelton, Elaine

doi:10.1111/j.1471-4159.1983.tb13565.x

Cited by 82 publications

(36 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similar data for NET demonstrated competitive inhibition of transport by DMI (11) and competitive displacement of DMI by NE (12). Until these differences are resolved, it is prudent to question whether TCA binding to the human transporters really is similar to the phenomenon described in these papers with LeuT.…”

mentioning

confidence: 60%

What Is an Antidepressant Binding Site Doing in a Bacterial Transporter?

Rudnick

2007

ACS Chem. Biol.

View full text Add to dashboard Cite

LeuT is a bacterial amino acid transporter belonging to a large family of membrane proteins, including the neurotransmitter transporters that are targets for antidepressant drugs. The high-resolution structure of LeuT has provided an important model for understanding structure and function in this family. Two recent papers found that LeuT can bind tricyclic antidepressants, raising the possibility that it may also serve as a model for the pharmacological properties of neurotransmitter transporters.

show abstract

mentioning

confidence: 60%

What Is an Antidepressant Binding Site Doing in a Bacterial Transporter?

Rudnick

2007

ACS Chem. Biol.

View full text Add to dashboard Cite

show abstract

“…In addition to transport into presynaptic nerve terminals, neurotransmitters may also be accumulated in some non-neuronal cells, such as myocytes and glia (Iversen, 1965;Henn & Hamberger, 1971;Hosli & Hosli, 1978;Kimelberg & Pelton, 1983;Bouvier et al, 1992;Pines et Chloroquine inhibited the uptake of (-)-noradrenaline (10-M) in the SK-N-SH cells, presumably by increasing the pH of neurosecretory vesicles which store noradrenaline in these cells: IC50 8 x 10-6 M. Chloroquine also inhibited uptake of prazosin (10' M) in GnRH cells (b) (IC50 6.8 x 10-M). This effect of chloroquine which is exerted within the range of concentrations at which it alters intracellular pH (Ohkuma & Poole, 1978;Maxfield, 1982), confirms that uptake of prazosin in these cells is dependent on a proton gradient.…”

Section: Comparison Of Gnrh Cells and Cos-7 Cellsmentioning

confidence: 99%

Functional properties of the uptake of amines in immortalised peptidergic neurones (transport‐P)

Al-Damluji

Kopin

1996

British J Pharmacology

View full text Add to dashboard Cite

1Most neurotransmitters are inactivated by uptake into presynaptic nerve terminals and into glial cells. We recently provided evidence for uptake of amines in postsynaptic neurones. Uptake was evident at nanomolar concentrations of prazosin, but at concentrations of unlabelled prazosin greater than 10-M, there was a further activation of uptake, manifested by a paradoxical increase in accumulation of the radioligand. We have now studied further characteristics of amine uptake in immortalised gonadotrophin-releasing hormone (GnRH) neurones. Control cells included SK-N-SH neuroblastoma cells (which possess presynaptic type amine transporters) and non-neuronal (COS-7) cells. 2 [3H]-prazosin bound to intact GnRH cells and was displaced by unlabelled prazosin in concentrations of 10-to 10-' M. However, at higher concentrations of unlabelled prazosin, there was an increase in apparent [3H]-prazosin binding, as we had previously described. This paradoxical increase in accumulation of the radioligand was abolished by desipramine. 3 Desipramine had no effect on the association of prazosin with COS-7 cells. There was no paradoxical increase in accumulation of [3H]-prazosin in COS-7 cells, indicating that this effect requires the presence of a desipramine-blockable uptake process. 4 The increase in binding of the radioligand that was observed in the GnRH cells is not a general property of neuronal transporters; in SK-N-SH cells, there was no increase in accumulation of (-)-[3H]-noradrenaline in the presence of concentrations of unlabelled (-)-noradrenaline greater than 10-7 M. 5 The uptake of prazosin and the increase in accumulation of [3H]-prazosin were abolished in the cold, indicating that this is an active, energy-requiring process. 6 Desipramine-sensitive uptake of prazosin was demonstrable in the GnRH cells in the absence of sodium. Further, the Na+/K+-ATPase inhibitor, vanadate, abolished noradrenaline uptake in SK-N-SH cells but had no effect on prazosin uptake in GnRH cells. Thus, the uptake of prazosin does not derive its energy from the sodium pump.7 Prazosin uptake was inhibited by the V-ATPase inhibitor bafilomycin Al, the H+/Na+ ionophore, monensin and the organic base, chloroquine, indicating that uptake derives its energy from a proton pump. In contrast to other proton-dependent amine transporters, the uptake of prazosin was unaffected by reserpine. 8 Increasing extracellular pH did not increase the uptake of prazosin into GnRH cells, indicating that it is unlikely to be due to non-specific diffusion and concentration of a lysosomotropic drug into intracellular acidic particles. 9 The uptake of prazosin was unaffected by steroid hormones.10 In COS-7 cells transfected with ocl-adrenoceptor cDNA, [3H]-prazosin was displaced by unlabelled prazosin without causing an increase in binding of the radioligand. This indicated that the increase in accumulation of the radioligand is unlikely to be due simply to some function of a,-adrenoceptors.11 Thus, peptidergic neurones possess an uptake process with properties ...

show abstract

“…First, binding of IMI to SERT is sodium-dependent. 120 Second, IMI 142 and DMI 145 are competitive inhibitors of 5HT and NE transport by SERT and NET, respectively, while CMI is a noncompetitive inhibitor of alanine transport by LeuT. 47 Third, there is at least a five-order of magnitude increase in the TCA IC 50 for substrate transport by LeuT 47 relative to the IC 50 for substrate transport by human SERT/NET.…”

Section: Discussionmentioning

confidence: 99%

“…The functional relevance of the "stabilized" structure is anticonvulsants, 19 block reuptake of the respective neurotransmitter from the synapse. For inhibitors, kinetic data have revealed the existence of both competitive [142][143][144][145][146] and noncompetitive 143,147 modes of inhibition. For some nontransportable, competitive drugs like the SSRI citalopram, convincing biochemical evidence for a primary binding site that overlaps with that of the substrate 5-HT 148 was acquired before the LeuT structure was published but is now also supported by LeuT-based homology models of SERT.…”

Section: Mechanism Of Inhibitionmentioning

confidence: 99%

LeuT: A prokaryotic stepping stone on the way to a eukaryotic neurotransmitter transporter structure

Singh¹

2008

Channels

View full text Add to dashboard Cite

To cite this article: Satinder K. Singh (2008) LeuT: A prokaryotic stepping stone on the way to a eukaryotic neurotransmitter transporter structure, Channels Ion-coupled secondary transport is utilized by a broad range of integral membrane proteins to catalyze the energetically unfavorable movement of solute molecules across a lipid bilayer. Members of the solute carrier 6 (SLC6) family, present in both prokaryotes and eukaryotes, are sodium-coupled symporters that play crucial roles in processes as diverse as nutrient uptake and neurotransmitter clearance. The crystal structure of LeuT, a bacterial member of this family, provided the first atomic-level glimpse into overall architecture, pinpointed the substrate and sodium binding sites and implicated candidate helices and residues in the "gating" conformational changes that accompany ion binding and release. The structure is consistent with a wealth of elegant biochemical data on the eukaryotic counterparts and has for the first time permitted the construction of accurate homology models that can be directly tested experimentally. Sequence identity is especially high near the substrate and sodium binding sites and, thus, molecular insights within these regions have been substantial. However, there are several topics relevant to transport mechanism, inhibition and regulation that structure/function studies of LeuT cannot adequately address, suggesting the need for a eukaryotic transporter crystal structure.

show abstract

High‐Affinity Uptake of [³H]Norepinephrine by Primary Astrocyte Cultures and Its Inhibition by Tricyclic Antidepressants

Cited by 82 publications

References 28 publications

What Is an Antidepressant Binding Site Doing in a Bacterial Transporter?

What Is an Antidepressant Binding Site Doing in a Bacterial Transporter?

Functional properties of the uptake of amines in immortalised peptidergic neurones (transport‐P)

LeuT: A prokaryotic stepping stone on the way to a eukaryotic neurotransmitter transporter structure

Contact Info

Product

Resources

About

High‐Affinity Uptake of [3H]Norepinephrine by Primary Astrocyte Cultures and Its Inhibition by Tricyclic Antidepressants

Cited by 82 publications

References 28 publications

What Is an Antidepressant Binding Site Doing in a Bacterial Transporter?

What Is an Antidepressant Binding Site Doing in a Bacterial Transporter?

Functional properties of the uptake of amines in immortalised peptidergic neurones (transport‐P)

LeuT: A prokaryotic stepping stone on the way to a eukaryotic neurotransmitter transporter structure

Contact Info

Product

Resources

About

High‐Affinity Uptake of [³H]Norepinephrine by Primary Astrocyte Cultures and Its Inhibition by Tricyclic Antidepressants