Preparation of [<sup>123</sup>I]‐ and [<sup>125</sup>I]epidepride: A dopamine D‐2 receptor antagonist radioligand

Clanton, Jeffrey A.; Schmidt, D. E.; Ansari, M. Sib; Manning, Ronald G.; Baldwin, Ronald M.; Kessler, Robert

doi:10.1002/jlcr.2580290703

Cited by 29 publications

(6 citation statements)

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“…Epidepride (( S )-N-[((l-ethyl-2-pyrrolidinynmethyl-5-iodo-2,3-dimethoxybenzamide) and ( S )- N -[(l-ethyl-2-pyrrolidinynmethyll-5-tri-n-butyltin-2,3-dimethoxybenzamide were prepared by using previously reported methods (Clanton et al, 1991; Kessler et al, 1991). Radiolabeling of the tributyltin precursor to produce ( S )-N-[(l-ethyl-2-pyrrolidinyl)methyl]-5- 124 I-iodo-2,3-dimethoxybenzamide was carried out using the following procedures: To the vial of no-carrier-added Na 124 I (commercially supplied in 0.02 M NaOH, IBA Molecular) (3.0 mCi, approx 30μL), 0.5N aq.…”

Section: Methodsmentioning

confidence: 99%

124I-Epidepride: A PET radiotracer for extended imaging of dopamine D2/D3 receptors

Pandey

Venugopal

Kant

et al. 2014

Nuclear Medicine and Biology

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Objectives A new radiotracer, 124I-epidepride, has been developed for the imaging of dopamine D2/3 receptors (D2/3Rs). 124I-epidepride (half-life of 124I = 4.2days) allows imaging over extended periods compared to 18F-fallypride (half-life of 18F = 0.076days) and may maximize visualization of D2/3Rs in the brain and pancreas (allowing clearance from adjacent organs). D2/3Rs are also present in pancreatic islets where they co-localize with insulin to produce granules and may serve as a surrogate marker for imaging diabetes. Methods 124I-Epidepride was synthesized using N-[[(2S)-1-ethylpyrrolidin-2-yl]methyl]-5-tributyltin-2,3-dimethoxybenzamide and 124I-iodide under no carrier added condition. Rats were used for in vitro and in vivo imaging. Brain slices were incubated with 124I-epidepride (0.75μCi/cc) and nonspecific binding measured with 10 μM haloperidol. Autoradiograms were analyzed by OptiQuant. 124I-Epidepride (0.2 to 0.3 mCi, iv) was administered to rats and brain uptake at 3 hours, 24 hours, and 48 hours post injection was evaluated. Results 124I-Epidepride was synthesized with 50% radiochemical yield and high radiochemical purity (>95%). 124I-Epidepride localized in the striatum with a striatum to cerebellum ratio of 10. Binding was displaced by dopamine and haloperidol. Brain slices demonstrated localization of 124I-epidepride up until 48 hr in the striatum. However, the extent of binding was reduced significantly. Conclusions 124I-Epidepride is a new radiotracer suitable for extended imaging of dopamine D2/3 receptors and may have applications in imaging of receptors in the brain and monitoring pancreatic islet cell grafting.

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Section: Methodsmentioning

confidence: 99%

124I-Epidepride: A PET radiotracer for extended imaging of dopamine D2/D3 receptors

Pandey

Venugopal

Kant

et al. 2014

Nuclear Medicine and Biology

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“…Binding to the D 2 /D 3 receptor subtypes was determined using quantitative receptor autoradiography and [ 125 I]epidepride as the ligand (Clanton et al 1991). Using the experimental conditions described below, raclopride (200 nM) completely inhibited the binding of epidepride.…”

Section: Quantitative Receptor Autoradiography (Qra)mentioning

confidence: 99%

Dopamine D₂ Receptor Binding, Drd2 Expression and the Number of Dopamine Neurons in the BXD Recombinant Inbred Series: Genetic Relationships to Alcohol and Other Drug Associated Phenotypes

Hitzemann

Rivera

et al. 2003

Alcoholism Clin & Exp Res

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The range of difference in receptor binding for the RI strains was approximately 2-fold in all regions examined, the core, the shell of the nucleus accumbens (NAc) and the dorsomedial caudate-putamen (CPu); heritability in all regions was moderate--(h2 approximately 0.35). Drd2 expression in forebrain samples from the RI and parental strains ranged 1.5- to h2-fold and was moderate-0.47. Variation in the number of tyrosine hydroxylase (TH) positive neurons was moderate, 41% and 26% and h2 was low--0.19 and 0.15 for the ventral tegmental area (VTA) and substantia nigra compacta (SNc), respectively. Significant correlations were found between D2 DA receptor binding and the low dose (1.33 g/kg) ethanol stimulant response. (p < 0.002) and between expression and conditioned place preference (CPP) (p < 0.0005). No significant correlations were detected between ethanol preference and either receptor binding or Drd2 expression; however, a significant correlation was found between preference and Ncam expression. Ncam is approximately 0.2 Mb from Drd2. Overall, the data suggest ethanol preference and CPP are associated with the expression of Drd2 or closely linked genetic loci.

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“…zamide] was prepared from its tributyltin precursor using a modification (Neve et al, 1991) of the method of Clanton et al (1991). Tissue preparation and saturation analysis of D3 receptor density were carried out essentially as described (Neve et al, 1990(Neve et al, , 1991.…”

Section: Radioligand Binding Assaysmentioning

confidence: 99%

Regulation and functional characterization of a rat recombinant dopamine D3 receptor

Cox

Rosser

Kozlowski

et al. 1995

Synapse

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We stably expressed a rat D3 receptor cDNA in C6 glioma cells (C6-D3 cells), quantifying receptor expression with the radioligands [125I]epidepride (KD = 0.1 nM) and [3H]spiperone (KD = 0.7 nM). As reported previously for D2 receptors, quinpirole induced a 9-16% increase in the rate of extracellular acidification by C6-D3 cells. The acidification was inhibited by epidepride and by the Na+/H+ antiporter inhibitors, amiloride and methylisobutylamiloride, but pertussis toxin treatment had no effect on quinpirole-induced extracellular acidification. These data suggest that D3 receptor stimulation of Na+/H+ exchange in C6 glioma cells is not mediated by the pertussis toxin-sensitive G proteins, Gi or G(o). Overnight treatment of C6-D3 cells with N-propylnorapomorphine, dopamine, or quinpirole resulted in large concentration-dependent increases (up to 500%) in the density of D3 receptors on membranes prepared from the cells. Antagonists had smaller, variable effects on the density of D3 receptors in C6-D3 cells, except for domperidone, which significantly increased the density of D3 receptors. Treatment with pertussis toxin had no effect on the agonist-induced receptor up-regulation, indicating that an interaction with pertussis toxin-sensitive G proteins was not required. Densitometry analysis of Northern blots of RNA prepared from C6-D3 cells showed no significant N-propylnorapomorphine-induced increase in D3 receptor message. Treatment with cycloheximide, however, completely prevented receptor up-regulation by N-propylnorapomorphine. Pretreatment of C6-D2 cells with 10 microM DA resulted in a substantial heterologous sensitization, in which isoproterenol-stimulated adenylyl cyclase activity was enhanced more than twofold.(ABSTRACT TRUNCATED AT 250 WORDS)

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Preparation of [¹²³I]‐ and [¹²⁵I]epidepride: A dopamine D‐2 receptor antagonist radioligand

Cited by 29 publications

References 21 publications

124I-Epidepride: A PET radiotracer for extended imaging of dopamine D2/D3 receptors

124I-Epidepride: A PET radiotracer for extended imaging of dopamine D2/D3 receptors

Dopamine D₂ Receptor Binding, Drd2 Expression and the Number of Dopamine Neurons in the BXD Recombinant Inbred Series: Genetic Relationships to Alcohol and Other Drug Associated Phenotypes

Regulation and functional characterization of a rat recombinant dopamine D3 receptor

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Preparation of [123I]‐ and [125I]epidepride: A dopamine D‐2 receptor antagonist radioligand

Cited by 29 publications

References 21 publications

124I-Epidepride: A PET radiotracer for extended imaging of dopamine D2/D3 receptors

124I-Epidepride: A PET radiotracer for extended imaging of dopamine D2/D3 receptors

Dopamine D2 Receptor Binding, Drd2 Expression and the Number of Dopamine Neurons in the BXD Recombinant Inbred Series: Genetic Relationships to Alcohol and Other Drug Associated Phenotypes

Regulation and functional characterization of a rat recombinant dopamine D3 receptor

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Preparation of [¹²³I]‐ and [¹²⁵I]epidepride: A dopamine D‐2 receptor antagonist radioligand

Dopamine D₂ Receptor Binding, Drd2 Expression and the Number of Dopamine Neurons in the BXD Recombinant Inbred Series: Genetic Relationships to Alcohol and Other Drug Associated Phenotypes