Synthesis, radioiodination and in vitro and in vivo sigma receptor studies of N-1-allyl-N´-4-phenethylpiperazine analogs.
Nucl Med Biol
; 39(3): 401-14, 2012 Apr.
Article
en En
| MEDLINE
| ID: mdl-22172395
ABSTRACT
INTRODUCTION:
Sigma-1 (σ(1)) receptor radioligands are useful for basic pharmacology studies and for imaging studies in neurology, psychiatry and oncology. We derived a hybrid structure, N-1-allyl-N´-4-phenethylpiperazine, from known ligands TPCNE and SA4503 for use as a scaffold for development of radioiodinated σ(1) receptor ligands.METHODS:
E-and Z-N-1-(3'-iodoallyl)-N´-4-(3â³,4â³-dimethoxyphenethyl)-piperazine (E-1 and Z-1), N-1-allyl-N´-4-(3',4'-dimethoxyphenethyl)-piperazine (2) and E-N-1-(3'-iodoallyl)-N´-4-(3â³-methoxy-4'´-hydroxyphenethyl)-piperazine (3) were synthesized. Affinities for σ(1) and σ(2) receptors were determined. [(125)I]E-1 and [(125)I]Z-1 were prepared and evaluated in vivo in mice. [(125)I]E-1 was further evaluated in σ(1) receptor binding assays in vitro.RESULTS:
E-1 displayed moderately high apparent affinity (15 nM) for σ(1) sites and 84-fold selectivity against σ(2) sites. Z-1 showed similar σ(1) affinity, but only 23-fold selectivity. In contrast, 2 exhibited poor binding to both subtypes, while 3 had good affinities but poor selectivity. E-1 profiled as a probable antagonist in the phenytoin shift assay. [(125)I]E-1 and [(125)I]Z-1 were prepared in good yields and with high specific radioactivities. Log D(7.4) values (2.25 and 2.27) fall within the optimal range for in vivo studies. Both radioligands selectively labeled σ(1) receptors in mouse brain and peripheral organs in vivo. [(125)I]E-1 showed a higher level of specific binding than [(125)I]Z-1 and displayed good metabolic stability. Further, [(125)I]E-1 selectively labeled σ(1) receptors in mouse brain homogenates (K(d) 3.79 nM; B(max)=599 fmol/mg protein).CONCLUSIONS:
[(125)I]E-1 is a selective σ(1) receptor radioligand that exhibits properties amenable to in vitro and in vivo studies, with possible extension to single photon emission computed tomography using iodine-123.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Piperazinas
/
Receptores sigma
/
Radioisótopos de Yodo
Tipo de estudio:
Evaluation_studies
Límite:
Animals
Idioma:
En
Revista:
Nucl Med Biol
Asunto de la revista:
BIOLOGIA
/
MEDICINA NUCLEAR
Año:
2012
Tipo del documento:
Article
País de afiliación:
Estados Unidos