RESUMEN
Inflammation has been linked to the development of nonmotor symptoms in Parkinson's disease (PD), which greatly impact patients' quality of life and can often precede motor symptoms. Suitable animal models are critical for our understanding of the mechanisms underlying disease and the associated prodromal disturbances. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkey model is commonly seen as a "gold standard" model that closely mimics the clinical motor symptoms and the nigrostriatal dopaminergic loss of PD, however MPTP toxicity extends to other nondopaminergic regions. Yet, there are limited reports monitoring the MPTP-induced progressive central and peripheral inflammation as well as other nonmotor symptoms such as gastrointestinal function and microbiota. We report 5 cases of progressive parkinsonism in non-human primates to gain a broader understanding of MPTP-induced central and peripheral inflammatory dysfunction to understand the potential role of inflammation in prodromal/pre-motor features of PD-like degeneration. We measured inflammatory proteins in plasma and CSF and performed [18F]FEPPA PET scans to evaluate translocator proteins (TSPO) or microglial activation. Monkeys were also evaluated for working memory and executive function using various behavior tasks and for gastrointestinal hyperpermeability and microbiota composition. Additionally, monkeys were treated with a novel TNF inhibitor XPro1595 (10 mg/kg, n = 3) or vehicle (n = 2) every three days starting 11 weeks after the initiation of MPTP to determine whether XPro1595 would alter inflammation and microglial behavior in a progressive model of PD. The case studies revealed that earlier and robust [18F]FEPPA PET signals resulted in earlier and more severe parkinsonism, which was seen in male cases compared to female cases. Potential other sex differences were observed in circulating inflammation, microbiota diversity and their metabolites. Additional studies with larger group sizes of both sexes would enable confirmation and extension of these findings. If these findings reflect potential differences in humans, these sex differences have significant implications for therapeutic development of inflammatory targets in the clinic.
Asunto(s)
Modelos Animales de Enfermedad , Microbioma Gastrointestinal , Inflamación/metabolismo , Macaca mulatta , Microglía/metabolismo , Trastornos Parkinsonianos/fisiopatología , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina , Anilidas , Animales , Conducta Animal , Cognición/fisiología , Progresión de la Enfermedad , Ácidos Grasos Volátiles/metabolismo , Femenino , Imagen por Resonancia Magnética , Masculino , Microglía/efectos de los fármacos , Microglía/patología , Neurotoxinas , Trastornos Parkinsonianos/diagnóstico por imagen , Trastornos Parkinsonianos/metabolismo , Trastornos Parkinsonianos/microbiología , Tomografía de Emisión de Positrones , Piridinas , Inhibidores del Factor de Necrosis Tumoral/farmacología , Factor de Necrosis Tumoral alfa/farmacologíaRESUMEN
CXCR4 is involved in various diseases such as inflammation, tumor growth, and cancer metastasis through the interaction with its natural endogenous ligand, chemokine CXCL12. In an effort to develop imaging probes for CXCR4, we developed a novel small molecule CXCR4-targeted PET agent (compound 5) by combining our established benzenesulfonamide scaffold with a labeling component by virtue of click chemistry. 5 shows nanomolar affinity (IC50 = 6.9 nM) against a known CXCR4 antagonist (TN14003) and inhibits more than 65% chemotaxis at 10 nM in vitro assays. Radiofluorinated compound 5 ([18F]5) demonstrates a competitive cellular uptake against CXCL12 in a dose-dependent manner. Further, microPET images of [18F]5 exhibits preferential accumulation of radioactivity in the lesions of λ-carrageenan-induced paw edema, human head and neck cancer orthotopic xenograft, and metastatic lung cancer of each mouse model.
Asunto(s)
Carcinoma de Células Escamosas/diagnóstico por imagen , Neoplasias de Cabeza y Cuello/diagnóstico por imagen , Tomografía de Emisión de Positrones , Radiofármacos/farmacología , Receptores CXCR4/antagonistas & inhibidores , Sulfonamidas/farmacología , Animales , Carragenina/administración & dosificación , Relación Dosis-Respuesta a Droga , Edema/inducido químicamente , Edema/tratamiento farmacológico , Edema/metabolismo , Femenino , Humanos , Inflamación/inducido químicamente , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Inyecciones Subcutáneas , Ligandos , Masculino , Ratones , Ratones Desnudos , Estructura Molecular , Radiofármacos/síntesis química , Radiofármacos/química , Receptores CXCR4/metabolismo , Relación Estructura-Actividad , Sulfonamidas/síntesis química , Sulfonamidas/química , Distribución Tisular , BencenosulfonamidasRESUMEN
Compounds 1-14 were synthesized in a search for high-affinity CRF1 receptor ligands that could be radiolabeled with (11)C or (18)F for use as positron emission tomography (PET) radiotracers. Derivatives of 2 were developed which contained amide N-fluoroalkyl substituents. Compounds [(18)F]24 and [(18)F]25 were found to have appropriate lipophilicities of logP7.4=2.2 but microPET imaging with [(18)F]25 demonstrated limited brain uptake.
Asunto(s)
Aminopiridinas/farmacología , Encéfalo/metabolismo , Compuestos Heterocíclicos con 2 Anillos/farmacología , Pirazinas/farmacología , Radiofármacos/farmacología , Receptores de Hormona Liberadora de Corticotropina/metabolismo , Aminopiridinas/síntesis química , Aminopiridinas/metabolismo , Animales , Línea Celular , Radioisótopos de Flúor , Compuestos Heterocíclicos con 2 Anillos/síntesis química , Compuestos Heterocíclicos con 2 Anillos/metabolismo , Humanos , Ligandos , Macaca fascicularis , Masculino , Fragmentos de Péptidos/química , Tomografía de Emisión de Positrones , Pirazinas/síntesis química , Pirazinas/metabolismo , Radiofármacos/síntesis química , Radiofármacos/metabolismoRESUMEN
A series of 3-(2,4-dichlorophenyl)-N-alkyl-N-fluoroalkyl-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amines were synthesized and evaluated as potential positron emission tomography (PET) tracers for the corticotropin-releasing factor type-1 (CRF1) receptor. Compounds 27, 28, 29, and 30 all displayed high binding affinity (⩽1.2 nM) to the CRF1 receptor when assessed by in vitro competition binding assays at 23 °C, whereas a decrease in affinity (⩾10-fold) was observed with compound 26. The logP7.4 values of [(18)F]26-[(18)F]29 were in the range of â¼2.2-2.8 and microPET evaluation of [(18)F]26-[(18)F]29 in an anesthetized male cynomolgus monkey demonstrated brain penetrance, but specific binding was not sufficient enough to differentiate regions of high CRF1 receptor density from regions of low CRF1 receptor density. Radioactivity uptake in the skull, and sphenoid bone and/or sphenoid sinus during studies with [(18)F]28, [(18)F]28-d8, and [(18)F]29 was attributed to a combination of [(18)F]fluoride generated by metabolic defluorination of the radiotracer and binding of intact radiotracer to CRF1 receptors expressed on mast cells in the bone marrow. Uptake of [(18)F]26 and [(18)F]27 in the skull and sphenoid region was rapid but then steadily washed out which suggests that this behavior was the result of binding to CRF1 receptors expressed on mast cells in the bone marrow with no contribution from [(18)F]fluoride.
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Radioisótopos de Flúor/química , Marcaje Isotópico/métodos , Tomografía de Emisión de Positrones/métodos , Radiofármacos/química , Receptores de Hormona Liberadora de Corticotropina/metabolismo , Animales , Unión Competitiva , Técnicas de Química Sintética , Usos Diagnósticos de Compuestos Químicos , Radioisótopos de Flúor/farmacocinética , Humanos , Ligandos , Macaca fascicularis , Masculino , Radiofármacos/síntesis química , Radiofármacos/farmacocinética , Ratas Sprague-DawleyRESUMEN
The compound 1-(1-(2-(2-(2-fluoroethoxy)-4-(piperidin-4-yloxy)phenyl)acetyl)piperidin-4-yl)-3,4-dihydroquinolin-2(1H)-one (1) was synthesized and positively evaluated in vitro for high potency and selectivity with human oxytocin receptors. The positron emitting analogue, [F-18]1, was synthesized and investigated in vivo via PET imaging using rat and cynomolgus monkey models. PET imaging studies in female Sprague-Dawley rats suggested [F-18]1 reached the brain and accumulated in various regions of the brain, but washed out too rapidly for adequate quantification and localization. In vivo PET imaging studies in a male cynomolgus monkey suggested [F-18]1 had limited brain penetration while specific uptake of radioactivity significantly accumulated within the vasculature of the cerebral ventricles in areas representative of the choroid plexus.
Asunto(s)
Radioisótopos de Flúor/química , Tomografía de Emisión de Positrones , Receptores de Oxitocina/química , Animales , Encéfalo/diagnóstico por imagen , Células Cultivadas , Cromatografía Líquida de Alta Presión , Femenino , Humanos , Ligandos , Macaca fascicularis , Masculino , Modelos Animales , Ratas , Ratas Sprague-DawleyRESUMEN
Compound L-368,899 was successfully alkylated with [(11)C]iodomethane to generate the oxytocin receptor selective (2R)-2-amino-N-((2S)-7,7-dimethyl-1-(((4-(o-tolyl)piperazin-1-yl)sulfonyl)methyl)bicyclo[2.2.1]heptan-2-yl)-N-[(11)C]methyl-3-(methylsulfonyl)propanamide ([(11)C]1) with very high radiochemical purity and high specific activity. PET imaging studies were performed with [(11)C]1 to investigate brain penetration and oxytocin receptor uptake using rat and cynomolgus monkey models. For rat baseline scans, brain penetration was observed with [(11)C]1, but no specific uptake could be distinguished in the brain region. By administering a peptide oxytocin receptor selective antagonist for peripheral blocking of oxytocin receptors, the uptake of [(11)C]1 was amplified in the rat brain temporarily to enable some visual uptake within the rat brain. A baseline scan of [(11)C]1 in a cynomolgus monkey model resulted in no detectable specific uptake in anticipated regions, but activity did accumulate in the choroid plexus.
Asunto(s)
Encéfalo/diagnóstico por imagen , Canfanos/química , Radioisótopos de Carbono/química , Piperazinas/química , Tomografía de Emisión de Positrones , Radiofármacos , Receptores de Oxitocina/metabolismo , Células Receptoras Sensoriales/metabolismo , Alquilación , Animales , Macaca fascicularis , Modelos Animales , Estructura Molecular , RatasRESUMEN
BACKGROUND: Deficits in serotonergic neurotransmission have been implicated in the pathogenesis of depression and suicidality. The present study utilized a novel positron-emission tomography (PET) ligand to quantitate and compare brain regional serotonin transporter (SERT) binding potential in depressed patients with a past history of suicide attempts to that of healthy comparison subjects. METHOD: We used [(11) C]-ZIENT PET to label SERT in the serotonergic cell body rich brainstem, and forebrain projection fields. Quantitative PET emission data from 21 adults (10 healthy controls and 11 drug-free patients with major depression) was used for group comparison. SERT binding potential (BPND ) in eight MRI-based brain regions of interest (ROI) were compared in high-resolution PET images. RESULTS: SERT binding potential was significantly decreased in the midbrain/pons (P = .029) and putamen (P = .04) of depressed patients with a past suicide attempt relative to comparison subjects. Forebrain SERT binding was also reduced in the patient sample, though these region effects did not survive a multiple comparison correction. CONCLUSION: These results suggest that decreased availability of the brainstem and basal ganglia SERT represents a biomarker of depression and thus confirm and extend the role of dysregulation of brain serotonergic neurotransmission in the pathophysiology of depression and suicide.
Asunto(s)
Tronco Encefálico/metabolismo , Trastorno Depresivo Mayor/metabolismo , Tomografía de Emisión de Positrones/métodos , Putamen/metabolismo , Proteínas de Transporte de Serotonina en la Membrana Plasmática/metabolismo , Intento de Suicidio , Análisis de Varianza , Biomarcadores/metabolismo , Mapeo Encefálico/métodos , Tronco Encefálico/diagnóstico por imagen , Estudios de Casos y Controles , Trastorno Depresivo Mayor/diagnóstico por imagen , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética , Masculino , Nortropanos , Putamen/diagnóstico por imagen , Adulto JovenRESUMEN
[(18)F]2-Fluoroethyl-p-toluenesulfonate also called [(18)F]2-fluoroethyl tosylate has been widely used for labeling radioligands for positron emission tomography (PET). [(18)F]2-Fluoroethyl-4-bromobenzenesulfonate, also called [(18)F]2-fluoroethyl brosylate ([(18)F]F(CH2)2OBs), was used as an alternative radiolabeling agent to prepare [(18)F]FEOHOMADAM, a fluoroethoxy derivative of HOMADAM, by O-fluoroethylating the phenolic precursor. Purified by reverse-phase HPLC, the no-carrier-added [(18)F]F(CH2)2OBs was obtained in an average radiochemical yield (RCY) of 35%. The reaction of the purified and dried [(18)F]F(CH2)2OBs with the phenolic precursor was performed by heating in DMF and successfully produced [(18)F]FEOHOMADAM, after HPLC purification, in RCY of 21%.
Asunto(s)
Bencilaminas/síntesis química , Radioisótopos de Flúor/química , Radiofármacos/síntesis química , Marcaje IsotópicoRESUMEN
[(11) C]MENET, a promising norepinephrine transporter imaging agent, was prepared by Suzuki cross coupling of 1 mg N-t-Boc pinacolborate precursor with [(11) C]CH3 I in DMF using palladium complex generated in situ from Pd2 (dba)3 and (o-CH3 C6 H4 )3 P together with K2 CO3 as the co-catalyst, followed by deprotection with trifluoroacetic acid. This improved radiolabeling method provided [(11) C]MENET in high radiochemical yield at end of synthesis (EOS, 51 ± 3%, decay-corrected from end of (11) CH3 I synthesis, n = 6), moderate specific activity (1.5-1.9 Ci/µmol at EOS), and high radiochemical (>98%) and chemical purity (>98%) in a synthesis time of 60 ± 5 min from the end of bombardment.
Asunto(s)
Marcaje Isotópico/métodos , Morfolinas/síntesis química , Radiofármacos/síntesis química , Radioisótopos de Carbono/química , Morfolinas/químicaRESUMEN
Brain imaging studies using positron emission tomography (PET) have shown that long-term cocaine use is associated with lower levels of dopamine (DA) D2/D3 receptors (D2/D3R); less consistent are the effects on DA transporter (DAT) availability. However, most studies have been conducted in male subjects (humans, monkeys, rodents). In this study, we used PET imaging in nine drug-naïve female cynomolgus monkeys to determine if baseline measures of DAT, with [18F]FECNT, and D2/D3R availability, with [11C]raclopride, in the caudate nucleus, putamen and ventral striatum were associated with rates of cocaine self-administration and if these measures changed during long-term (~13 months) cocaine self-administration and following time-off (3-9 months) from cocaine. Cocaine (0.2 mg/kg/injection) and 1.0 g food pellets were available under a multiple fixed-interval (FI) 3-min schedule of reinforcement. In contrast to what has been observed in male monkeys, baseline D2/D3R availability was positively correlated with rates of cocaine self-administration only during the first week of exposure; DAT availability did not correlate with cocaine self-administration. D2/D3R availability decreased ~20% following cumulative intakes of 100 and 1000 mg/kg cocaine; DAT availability did not significantly change. These reductions in D2/D3R availability did not recover over 9 months of time-off from cocaine. To determine if these reductions were reversible, three monkeys were implanted with osmotic pumps that delivered raclopride for 30 days. We found that chronic treatment with the D2/D3R antagonist raclopride increased D2/D3R availability in the ventral striatum but not in the other regions when compared to baseline levels. Over 13 months of self-administration, tolerance did not develop to the rate-decreasing effects of self-administered cocaine on food-reinforced responding, but number of injections and cocaine intake significantly increased over the 13 months. These data extend previous findings to female monkeys and suggest sex differences in the relationship between D2/D3R availability related to vulnerability and long-term cocaine use.
Asunto(s)
Cocaína , Tomografía de Emisión de Positrones , Haplorrinos , Animales , Femenino , Tomografía de Emisión de Positrones/métodos , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Receptores de Dopamina D3 , Cocaína/administración & dosificación , Cocaína/efectos adversos , Autoadministración , RaclopridaRESUMEN
Compounds 1-4 were synthesized and investigated for selectivity and potency for the oxytocin receptor (OTR) to determine their viability as radioactive ligands. Binding assays determined 1-4 to have high binding affinity for both the human and rodent OTR and also have high selectivity for the human OTR over human vasopressin V1a receptors (V1aR). Inadequate selectivity for OTR over V1aR was found for rodent receptors in all four compounds. The radioactive (C-11, F-18, and I-125) derivatives of 1-4 were synthesized and investigated for use as autoradiography and positron emission tomography (PET) ligands. Receptor autoradiography performed with [(125)I]1 and [(125)I]2 on rodent brain slices provided the first small molecule radioligand images of the OTR and V1aR. Biodistribution studies determined [(125)I]1 and [(125)I]2 were adequate for in vivo peripheral investigations, but not for central investigations due to low uptake within the brain. A biodistribution study with [(18)F]3 suggested brain uptake occurred slowly over time. PET imaging studies with [(18)F]3 and [(11)C]4 using a rat model provided insufficient uptake in the brain over a 90 and 45 min scan times respectively to merit further investigations in non-human primates.
Asunto(s)
Piperidinas , Quinolinas , Radiofármacos/síntesis química , Receptores de Oxitocina/análisis , Animales , Arvicolinae , Autorradiografía , Unión Competitiva , Isótopos de Carbono , Línea Celular , Femenino , Radioisótopos de Flúor , Humanos , Radioisótopos de Yodo , Ligandos , Estructura Molecular , Peso Molecular , Piperidinas/síntesis química , Piperidinas/farmacocinética , Tomografía de Emisión de Positrones , Quinolinas/síntesis química , Quinolinas/farmacocinética , Ensayo de Unión Radioligante , Radiofármacos/farmacocinética , Ratas , Ratas Sprague-Dawley , Relación Estructura-Actividad , Distribución TisularRESUMEN
The serotonin 5-HT2 C receptor (5-HT2 C R) is abundantly expressed throughout the central nervous system, and involved in a variety of neuroendocrine and neurobehavioral processes. The development of a selective radioligand that will enable in vivo imaging and quantification of 5-HT2 C R densities represents a significant technological advancement in understanding both the normal function and pathophysiology of the 5-HT2 C R. Four 7-halogen-2-phenyl isoindolones (7-F, Cl, Br, I) were synthesized and displayed high affinities for 5-HT2 C R and high selectivity over 5-HT2 A and 5-HT2 B . [11C]7-Chloro-2-[4-methoxy-3-[2-(4-methylpiperidin-1-yl)ethoxy]phenyl]isoindolin-1-one (6) and [11C]7-iodo-2-[4-methoxy-3-[2-(4-methylpiperidin-1-yl)ethoxy]phenyl]isoindolin-1-one (9) were synthesized in high radiochemical yield of 37-44% [n = 10, decay corrected from end of (11C)CH3I synthesis] with high radiochemical purity via O-methylation with [11C]CH3I, respectively. MicroPET imaging studies in male rats with or without 5-HT2 C antagonist SB-242084 showed that [11C]6 and [11C]9 display specific bindings to 5-HT2 C R in the choroid plexus and hippocampus. In vivo microPET brain imaging studies in rhesus monkeys demonstrated that [11C]6 and [11C]9 exhibit excellent blood-brain barrier penetration. The contrast of bindings to the choroid plexus and hippocampus compared to the cerebellum peaked at 2.7 and 1.6, respectively, for [11C]6, and 3.7 and 2.7, respectively, for [11C]9, which were reduced by administration of a dose of SB-242084. Our results support the candidacy of [11C]6 and [11C]9 for further study as radioligands for in vivo quantitation of 5-HT2 C sites by PET.
RESUMEN
The enantiomeric non-natural cyclic amino acids (3R,4R)-1-amino-3-fluoro-4-(fluoro-18F)cyclopentane-1-carboxylic acid and (3S,4S)-1-amino-3-fluoro-4-(fluoro-18F)cyclopentane-1-carboxylic acid ([ 18 F]5) have been prepared as a racemic mixture in 1.3% decay corrected radiochemical yield and in greater than 99% radiochemical purity. [ 18 F]5 is transported primarily via system L with some transport occurring via system ASC, as assessed in rat 9L gliosarcoma, human U87 ΔEGFR glioblastoma, and human DU145 androgen-independent prostate carcinoma tumor cells. In rats bearing intracranial 9L gliosarcoma, [ 18 F]5 gave tumor to contralateral brain tissue ratios of up to 2.8. Biodistribution studies in healthy rats demonstrated that bladder accumulation is delayed until 10 min postinjection.
RESUMEN
Currently, there is no large animal model of sustained limb ischemia suitable for testing novel angiogenic therapeutics for peripheral artery disease (PAD) such as drugs, genes, materials, or cells. We created a large animal model suitable for efficacy assessment of these therapies by testing 3 swine hind limb ischemia (HLI) variations and quantifying vascular perfusion, muscle histology, and limb function. Ligation of the ipsilateral external and bilateral internal iliac arteries produced sustained gait dysfunction compared to isolated external iliac or unilateral external and internal iliac artery ligations. Hyperemia-dependent muscle perfusion deficits, depressed limb blood pressure, arteriogenesis, muscle atrophy, and microscopic myopathy were quantifiable in ischemic limbs 6 weeks post-ligation. Porcine mesenchymal stromal cells (MSCs) engineered to express a reporter gene were visualized post-administration via positron emission tomography (PET) in vivo. These results establish a preclinical platform enabling better optimization of PAD therapies, including cellular therapeutics, increasing bench-to-bedside translational success. A preclinical platform for porcine studies of peripheral artery disease therapies including (1) a hind limb ischemia model and (2) non-invasive MSC viability and retention assessment via PET.
Asunto(s)
Modelos Animales de Enfermedad , Miembro Posterior/irrigación sanguínea , Isquemia/fisiopatología , Enfermedad Arterial Periférica/fisiopatología , Animales , Flujo Sanguíneo Regional , PorcinosRESUMEN
The non-natural cyclic amino acids (1S,3R,4S)-1-amino-3-fluoro-4-(fluoro-18F)cyclopentane-1-carboxylic acid ([18F]9) and (1S,3S,4R)-1-amino-3-fluoro-4-(fluoro-18F)cyclopentane-1-carboxylic acid ([18F]28) have been prepared in 10 and 1.7% decay corrected radiochemical yield, respectively, and in greater than 99% radiochemical purity. Cell assays in rat 9L gliosarcoma, human U87 ΔEGFR glioblastoma, and human DU145 androgen-independent prostate carcinoma tumor cells indicated that both compounds are substrates for amino acid transport primarily by system L, with some transport taking place via system ASC. In rats with 9L gliosarcoma, [18F]9 and [18F]28 provided high tumor to normal brain tissue ratios, with maximal ratios of 3.5 and 4.1, respectively. Biodistribution studies in healthy rats confirmed that both compounds are BBB permeable and that bladder accumulation is low until at least 5 min post injection.
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Ácidos Carboxílicos/química , Ciclopentanos/química , Glioblastoma/diagnóstico por imagen , Tomografía de Emisión de Positrones , Neoplasias de la Próstata/diagnóstico por imagen , Radiofármacos/química , Animales , Ácidos Carboxílicos/síntesis química , Ciclopentanos/síntesis química , Relación Dosis-Respuesta a Droga , Radioisótopos de Flúor , Humanos , Masculino , Conformación Molecular , Estructura Molecular , Radiofármacos/síntesis química , Radiofármacos/farmacocinética , Ratas , Estereoisomerismo , Relación Estructura-Actividad , Distribución Tisular , Células Tumorales CultivadasRESUMEN
N, N-dimethyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine (38), substituted on ring A, was reported to display high binding affinity and selectivity to the human brain serotonin transporter (SERT). In an attempt to explore the potential of compounds substituted on ring B of the phenylthiophenyl core structure, three derivatives of 38 were synthesized: N, N-dimethyl-2-(2'-amino-4'-hydroxymethyl-phenylthio)-5-fluorobenzylamine (35), N, N-dimethyl-2-(2'-amino-4'-hydroxymethyl-phenylthio)-5-bromobenzylamine (36), and N, N-dimethyl-2-(2'-amino-4'-hydroxymethyl-phenylthio)-5-iodobenzylamine (37). The in vitro binding studies in cells transfected with human SERT, norepinephrine transporter (NET), and dopamine transporter (DAT) showed that 35, 36, and 37 exhibited high SERT affinity with K is (SERT) = 1.26, 0.29, and 0.31 nM (vs [(3)H]citalopram), respectively. [(11)C]-(35), [(11)C]-(36), and [(11)C]-( 37) were prepared by methylation of their monomethyl precursors 16, 17, and 18, with [(11)C]iodomethane in 28, 11, and 14% radiochemical yields, respectively. The microPET images of [(11)C]-(35), [(11)C]-(36), and [(11)C]-(37) showed high uptake in the monkey brain regions rich in SERT with peak midbrain to cerebellum ratios of 3.41, 3.24, and 3.00 at 85 min post-injection, respectively. In vivo bindings of [(11)C]-(35), [(11)C]-(36), and [(11)C]-(37) were shown to be specific to the SERT as displacement with citalopram (a potent SERT ligand) reduced radioactivity in SERT-rich regions to the cerebellum level. These results suggest that [(11)C]-(35), [(11)C]-(36), and [(11)C]-(37) could be potential agents for mapping human SERT by PET and radiolabeling 37 with iodine-123, which could afford the first SPECT SERT imaging agent exhibiting fast kinetics.
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Bencilaminas/síntesis química , Radiofármacos/síntesis química , Proteínas de Transporte de Serotonina en la Membrana Plasmática/metabolismo , Sulfuros/síntesis química , Animales , Bencilaminas/química , Bencilaminas/farmacocinética , Unión Competitiva , Encéfalo/metabolismo , Radioisótopos de Carbono , Línea Celular , Humanos , Ligandos , Macaca fascicularis , Masculino , Tomografía de Emisión de Positrones , Unión Proteica , Radiofármacos/química , Radiofármacos/farmacocinética , Sulfuros/química , Sulfuros/farmacocinética , Distribución TisularRESUMEN
INTRODUCTION: 2-Methoxyestradiol (2ME2) is an endogenous metabolite of the human hormone, estrogen, which has been shown to possess anti-tumor activity. 2-Fluoroethoxyestradiol (2FEE2) and 2-fluoropropanoxyestradiol (2FPE2), novel analogs of 2-methoxyestradiol, were designed and synthesized to be utilized as F-18 radiotracers for positron emission tomography (PET), with which the bio-distribution and intratumoral accumulations of 2ME2 could be measured in vivo for potential translation to human use. METHODS: 2FEE2 and 2FPE2 were synthesized from 3,17beta-estradiol in five steps respectively. Drug-induced microtubule depolymerization, antiproliferative activity against human cancer cell lines and HIF-1alpha down-regulation by 2FEE2 and 2FPE2 were investigated to examine whether these molecules possess similar anti-tumor activities as 2-methoxyestradiol. 2-[(18)F]Fluoroethoxyestradiol was synthesized for PET. RESULTS: Novel 2ME2 analogs, 2FEE2 and 2FPE2, were synthesized in 29% and 22% overall yield, respectively. 2FEE2 and 2FPE2 showed microtubule depolymerization and cytotoxicities against the human ovarian carcinoma cell line, 1A9, and the human glioma cell line, LN229. HIF-1alpha was down-regulated by 2FEE2 and 2FPE2 under hypoxic conditions. 2FEE2 was chosen as an F-18 radiotracer candidate, since it showed stronger antiproliferative activity than 2ME2 and 2FPE2. 2-[(18)F]Fluoroethoxyestradiol (2[(18)F]FEE2) was prepared in 8.3% decay-corrected yield in 90 min, based on a production of H[(18)F]F with more than 98% radiochemical purity. CONCLUSIONS: 2FEE2 and 2FPE2 showed similar activity as 2ME2. 2[(18)F]FEE2 was synthesized to be utilized as a PET radiotracer to measure the biological efficacy of 2ME2 and its analogs in vivo.
Asunto(s)
Estradiol/análogos & derivados , Radiofármacos/síntesis química , 2-Metoxiestradiol , Línea Celular Tumoral , Regulación hacia Abajo/efectos de los fármacos , Estradiol/síntesis química , Femenino , Radioisótopos de Flúor , Glioma/radioterapia , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Subunidad alfa del Factor 1 Inducible por Hipoxia/biosíntesis , Indicadores y Reactivos , Marcaje Isotópico , Espectroscopía de Resonancia Magnética , Microtúbulos/diagnóstico por imagen , Neoplasias Ováricas/radioterapia , Tomografía de Emisión de Positrones , Control de Calidad , Distribución TisularRESUMEN
The isoquinoline carboxamide derivative 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide (PK11195) has been shown to bind strongly and selectively to the peripheral benzodiazepine receptor (PBR) binding sites. A series of PK11195 analogues have been synthesized and biologically characterized. The affinities of the analogues for the PBR were determined using in vitro competitive binding assays with [(3)H]PK11195 in rat kidney mitochondrial membranes. The results showed that the 1-(2-iodophenyl)-N-methyl-N-(3-fluoropropyl)-3-isoquinoline carboxamide (9a) was the most potent compound (K(i)=0.26nM) of this series and is an excellent lead ligand for additional studies for labeling with fluorine-18 to determine whether it possesses the desired in vivo performance in non-human primates by PET imaging. Thus, radiolabeling of 9a with fluorine-18 was developed.
Asunto(s)
Radioisótopos de Flúor , Isoquinolinas/síntesis química , Tomografía de Emisión de Positrones , Receptores de GABA-A/análisis , Receptores de GABA-A/metabolismo , Animales , Unión Competitiva/efectos de los fármacos , Isoquinolinas/química , Isoquinolinas/metabolismo , Riñón/química , Riñón/diagnóstico por imagen , Riñón/efectos de los fármacos , Ligandos , Membranas Mitocondriales/química , Membranas Mitocondriales/diagnóstico por imagen , Membranas Mitocondriales/efectos de los fármacos , Ensayo de Unión Radioligante , Radiofármacos/síntesis química , RatasRESUMEN
Six new (S,S)-enantiomers of reboxetine derivatives were synthesized and their binding affinities were determined via competition binding assays in cells expressing the human norepinephrine transporter (NET), serotonin transporter (SERT) or dopamine transporter (DAT). All six compounds prepared exhibit high affinity for the NET (K(i)Asunto(s)
Morfolinas/síntesis química
, Morfolinas/farmacocinética
, Proteínas de Transporte de Noradrenalina a través de la Membrana Plasmática/metabolismo
, Tomografía de Emisión de Positrones/métodos
, Radiofármacos/síntesis química
, Radiofármacos/farmacocinética
, Proteínas de Transporte Vesicular de Monoaminas/metabolismo
, Animales
, Encéfalo/metabolismo
, Radioisótopos de Carbono/farmacocinética
, Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo
, Radioisótopos de Flúor/farmacocinética
, Humanos
, Estructura Molecular
, Morfolinas/química
, Primates
, Ensayo de Unión Radioligante
, Radiofármacos/química
, Reboxetina
, Proteínas de Transporte de Serotonina en la Membrana Plasmática/metabolismo