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1.
EMBO J ; 42(13): e112987, 2023 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-37254647

RESUMO

Nucleoporins (Nups) assemble nuclear pores that form the permeability barrier between nucleoplasm and cytoplasm. Nucleoporins also localize in cytoplasmic foci proposed to function as pore pre-assembly intermediates. Here, we characterize the composition and incidence of cytoplasmic Nup foci in an intact animal, C. elegans. We find that, in young non-stressed animals, Nup foci only appear in developing sperm, oocytes and embryos, tissues that express high levels of nucleoporins. The foci are condensates of highly cohesive FG repeat-containing nucleoporins (FG-Nups), which are maintained near their solubility limit in the cytoplasm by posttranslational modifications and chaperone activity. Only a minor fraction of FG-Nup molecules concentrate in Nup foci, which dissolve during M phase and are dispensable for nuclear pore assembly. Nucleoporin condensation is enhanced by stress and advancing age, and overexpression of a single FG-Nup in post-mitotic neurons is sufficient to induce ectopic condensation and organismal paralysis. We speculate that Nup foci are non-essential and potentially toxic condensates whose assembly is actively suppressed in healthy cells.


Assuntos
Complexo de Proteínas Formadoras de Poros Nucleares , Poro Nuclear , Masculino , Animais , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Poro Nuclear/genética , Poro Nuclear/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Sêmen/metabolismo , Núcleo Celular/metabolismo , Transporte Ativo do Núcleo Celular
2.
Bioorg Med Chem ; 22(15): 3931-7, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-25023539

RESUMO

The 2-[(18)F]fluoro-3-pent-4-yn-1-yloxypyridine ([(18)F]FPyKYNE) analog of the potent non-peptide angiotensin II type 1 receptor (AT1R) blocker losartan was produced via click chemistry linking [(18)F]FPyKYNE to azide-modified tetrazole-protected losartan followed by TFA deprotection. Preliminary small animal imaging with positron emission tomography (PET) in rats displayed high uptake in the kidneys with good contrast to surrounding tissue. Rat metabolism displayed the presence of 23% unchanged tracer in plasma at 30 min. Upon co-administration with AT1R blocker candesartan (2.5, 5 and 10 mg/kg), a dose-dependent reduction (47-65%) in tracer uptake was observed in the kidney, while no difference was observed following AT2R blocker PD123,319 (5 mg/kg), indicating binding selectivity for AT1R over AT2R and potential for imaging AT1R using PET.


Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/síntese química , Losartan/química , Receptor Tipo 1 de Angiotensina/química , Bloqueadores do Receptor Tipo 1 de Angiotensina II/química , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Animais , Benzimidazóis/farmacologia , Compostos de Bifenilo , Radioisótopos de Flúor/química , Rim/diagnóstico por imagem , Rim/efeitos dos fármacos , Rim/metabolismo , Losartan/síntese química , Losartan/farmacologia , Masculino , Tomografia por Emissão de Pósitrons , Piridinas/química , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/química , Ratos , Ratos Sprague-Dawley , Receptor Tipo 1 de Angiotensina/metabolismo , Tetrazóis/química , Tetrazóis/farmacologia
3.
Can J Physiol Pharmacol ; 92(5): 375-85, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24754268

RESUMO

There is accumulating evidence suggesting that depression is a risk factor for cardiovascular diseases. This study aimed to examine the hypothesis that the proinflammatory cytokine TNF-α would partially explain the link between depression and atherosclerotic endothelial changes. Rats were distributed among 6 groups: (i) control group; (ii) group subjected to chronic mild stress (CMS); (iii) group fed a cholesterol-cholic acid-thiouracil (CCT diet); and (iv) CMS group fed the CCT diet and treated with the vehicle for 8 weeks. The last 2 groups were subjected to CMS-CCT and received thalidomide (THAL) or imipramine (IMIP). Rats were assessed behaviorally (sucrose preference, open field, and forced-swimming tests). TNF-α protein was assessed from the serum, aorta, and liver. Aortic TNF-α gene expression (assessed using RT-PCR), serum lipid profile, and insulin levels were measured. Endothelial function was assessed in isolated aortic rings. The THAL and IMIP groups showed ameliorated CMS-CCT-related behavioral changes. CMS-CCT-induced metabolic and endothelial dysfunctions were improved in the THAL group but were worsened in the IMIP group. RT-PCR showed a significant reduction of aortic TNF-α mRNA expression in the THAL and IMIP treatment groups. These data paralleled the findings for aortic immunohistochemistry. The THAL group, but not the IMIP group, showed improved CMS-CCT-induced changes in the vascular reactivity of the aortic rings. Thus, TNF-α provides a target link between depression, metabolic syndrome, and endothelial dysfunction. This could open a new therapeutic approach to address the comorbidities of depression.


Assuntos
Dieta Aterogênica/efeitos adversos , Endotélio Vascular/efeitos dos fármacos , Imunossupressores/farmacologia , Estresse Psicológico/metabolismo , Estresse Psicológico/psicologia , Talidomida/farmacologia , Fator de Necrose Tumoral alfa/metabolismo , Animais , Antidepressivos Tricíclicos/farmacologia , Aorta Torácica/metabolismo , Aorta Torácica/fisiopatologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Doença Crônica , Depressão/metabolismo , Depressão/psicologia , Endotélio Vascular/metabolismo , Endotélio Vascular/fisiopatologia , Imipramina/farmacologia , Resistência à Insulina , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/fisiopatologia , Óxido Nítrico/metabolismo , Ratos Wistar
4.
Clin Rheumatol ; 43(1): 219-226, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37574521

RESUMO

BACKGROUND: Imaging is crucial for identifying and diagnosis of the musculoskeletal (MSK) symptoms, which are one of the most typical manifestations of systemic lupus erythematosus (SLE). For the joints, tendons, and entheseal sites, ultrasonography has shown to be sensitive and accurate for the diagnosis of both inflammation and structural damage. AIM: The goal of the current investigation is to determine the prevalence and the distribution of entheseal abnormalities in SLE patients, using musculoskeletal ultrasonography (MSUS) and to assess the relationship between entheseal sonographic changes and the SLE disease activity. PATIENTS AND METHODS: One hundred sixty-eight subjects were studied (56 SLE patients, 56 psoriatic arthritis (PSA) patients, and 56 normal cases). To compare the frequency and the distribution of entheseal involvement, high-resolution MSUS was conducted to assess the entheseal sites of all patients in accordance with the Madrid Sonographic Enthesitis Index (MASEI). RESULTS: Clinical enthesitis was detected in 39.3% of the SLE patients using the Leeds Enthesitis Index compared to 71% detected via US examination, indicating a high proportion of subclinical enthesitis in our SLE patients. The most frequently affected enthesis was the distal insertion of the patellar tendon at the tibial tuberosity which was detected in 41% of SLE patients. Enthesitis was significantly more frequent in PSA patients (100%) compared to SLE patients (71.4%) (p < 0.05) and more significantly frequent in SLE patients compared to the healthy controls (19.6%). There was a significant correlation between MASI and SLEDAI scores (r = 0.250*, p = 0.048) and the total protein in 24 h (r = 0.289*, p = 0.031). In addition, there was an inverse significant correlation between MASEI and serum albumin (r = - 0.324*, p = 0.015). CONCLUSION: In SLE patients, enthesitis is frequently clinical and ultrasound-verified. The most impacted enthesis is at the insertion of the quadriceps tendon. Enthesitis presence and the rise in the MASI score can serve as indicators of the severity of the SLE disease. Key Points • The most impacted entheseal site lies at the insertion of the quadriceps tendon. • The presence and the rise in MASEI score can serve as indicators of the severity of the SLE disease.


Assuntos
Artrite Psoriásica , Entesopatia , Lúpus Eritematoso Sistêmico , Humanos , Ultrassonografia , Artrite Psoriásica/diagnóstico por imagem , Artrite Psoriásica/epidemiologia , Entesopatia/diagnóstico por imagem , Músculo Quadríceps , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/diagnóstico por imagem , Índice de Gravidade de Doença
5.
Sci Rep ; 13(1): 9196, 2023 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-37280267

RESUMO

The present investigation goal was to investigate the chemistry of four new mononuclear mixed ligand Fe(III), Co(II), Cu(II), and Cd(II) complexes constructed from furfural-type imine ligand (L), and the co ligand 2,2'-bipyridine in addition to assessing their antimicrobial activity against some bacterial, and fungi strains. The structure of the complexes was interpreted by different spectroscopic techniques such as MS, IR, 1H NMR, UV-Vis, elemental analysis, TG-DTG, conductivity, and magnetic susceptibility measurements. The correlation of all results revealed that ligand (L) acts as a neutral ONNO tetradentate whereas the co ligand acts as a neutral NN bidentate. The coordination of the ligands with the metal ions in a molar ratio of 1:1:1 leads to formation of an octahedral geometry around the metal ions. The octahedral geometry has been validated and optimized by DFT analysis. Conductivity data showed the electrolytic nature of all complexes. The thermal stability of all complexes was deduced in addition to evaluating some thermodynamic, and kinetic parameters using Coats-Redfern method. Furthermore, all complexes in comparison to their parent ligands were tested for their biological potency against some pathogenic bacterial, and fungi strains using the paper disk diffusion method. [CdL(bpy)](NO3)2 complex revealed the highest antimicrobial activity.


Assuntos
Anti-Infecciosos , Complexos de Coordenação , Iminas , Furaldeído , Ligantes , 2,2'-Dipiridil/farmacologia , Compostos Férricos , Complexos de Coordenação/química , Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Bactérias , Fungos , Íons , Testes de Sensibilidade Microbiana , Espectrofotometria Infravermelho , Bases de Schiff/química
6.
Oxid Med Cell Longev ; 2022: 4464180, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35774377

RESUMO

Atherosclerosis is a disease in which plaque builds up inside arteries. Cinnamaldehyde (Ci) has many biological properties that include anti-inflammatory and antioxidant activities. Thus, this study was designed to explore the protective effect of Ci against atherosclerosis induced by a high-fat diet (HFD) in Wistar rats. Atherosclerosis was induced by an oral administration of an HFD for 10 weeks. Atherosclerosis-induced rats were supplemented with Ci at a dose of 20 mg/kg bw dissolved in 0.5% dimethyl sulfoxide (DMSO), daily by oral gavage for the same period. Rats were divided into three groups of 10 rats each fed with (a) ND, (b) HFD, and (c) HFD+Ci, daily for 10 weeks. Treatment of rats with Ci significantly reduced the elevated levels of serum total cholesterol (T.Ch), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-Ch), very low-density lipoprotein-cholesterol (VLDL-Ch), and free fatty acids (FFAs) and significantly increased the lowered levels of high-density lipoprotein-cholesterol (HDL-Ch) level. Ci ameliorated the increased cardiovascular risk indices 1 and 2 and the decreased antiatherogenic index. Moreover, Ci reduced the elevated serum creatine kinase (CK), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) activities. Ci also improved the heart antioxidant activities by decreasing malondialdehyde (MDA) and increasing glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and glutathione peroxidase (Gpx) activities. Furthermore, the supplementation with Ci downregulated the mRNA expression levels of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), interleukin-17 (IL-17), and tumor necrosis factor-α (TNF-α). Thus, Ci successfully elicited a therapeutic impact against atherosclerosis induced by HFD via its hypolipidemic, antioxidant, and anti-inflammatory actions.


Assuntos
Aterosclerose , Hiperlipidemias , Acroleína/análogos & derivados , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Aterosclerose/tratamento farmacológico , LDL-Colesterol , Creatina Quinase , Dieta Hiperlipídica/efeitos adversos , Hiperlipidemias/tratamento farmacológico , Inflamação/tratamento farmacológico , Estresse Oxidativo , Ratos , Ratos Wistar
7.
Clin Transl Allergy ; 11(1): e12006, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33900046

RESUMO

BACKGROUND: Patients are often dissatisfied with the symptom control obtained from available pharmacological treatments for seasonal allergic rhinoconjunctivitis (ARC). Therefore, patients seek for alternative, nonpharmacological options to treat their symptoms. Here, we assessed the efficacy of ectoine nasal spray and ectoine eye drops in comparison to placebo to prevent nasal and ocular symptoms following exposure to pollen in patients with ARC. METHODS: In this double-blind, randomized, placebo-controlled, cross-over study, 46 patients with ARC applied ectoine eye drops and nasal spray in immediate succession or placebo eye drops and nasal spray for 13 days before ARC symptoms were induced in an environmental exposure chamber. Primary endpoint was the baseline-adjusted area under the curve (AUC) posttreatment total nasal symptom score (TNSS) and the total ocular symptom score (TOSS) using analysis of covariance. Secondary endpoints were, amongst others, total nonnasal symptoms score (TNNSS) and nasal patency (measured using acoustic rhinometry). RESULTS: Treatment with both ectoine and placebo reduced TNSS, TOSS, and TNNSS upon allergen exposure. The analysis of parameters at baseline and after allergen exposure demonstrated that ectoine induced a clinically relevant improvement in ARC symptoms compared to placebo: the least square mean difference for baseline-adjusted AUC was -1.87 for TNSS, -1.45 for TOSS and -2.20 for TNNSS. The mean change from baseline AUC of TNNSS for ectoine was also significantly greater than for placebo (-5.49 vs. -3.46; p = 0.011). Ectoine significantly improved the singular symptoms "sneezing," "watery eyes" and "itchy eyes" (p ≤ 0.021) as well as "itchy ear/palate" (p = 0.036) in comparison to placebo. Mean cross sectional areas of the nasal cavity were reduced to a lesser extent after treatment with ectoine (-0.020 ± 0.022) than with placebo (-0.047 ± 0.029). The current study also demonstrated a very good safety profile of ectoine treatment. Few AEs with comparable numbers in both treatment groups were reported during the study, which were mild in severity and resolved without medical treatment. CONCLUSION: The study suggests that ectoine is effective in reducing nasal and ocular symptoms associated with ARC. Being a natural, bacteria derived stress protection molecule functioning by a physical mode of action, it therefore represents an alternative nonpharmacological treatment option.

8.
Nat Commun ; 11(1): 4360, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32868762

RESUMO

The hypothalamus is a central regulator of many innate behaviors essential for survival, but the molecular mechanisms controlling hypothalamic patterning and cell fate specification are poorly understood. To identify genes that control hypothalamic development, we have used single-cell RNA sequencing (scRNA-Seq) to profile mouse hypothalamic gene expression across 12 developmental time points between embryonic day 10 and postnatal day 45. This identified genes that delineated clear developmental trajectories for all major hypothalamic cell types, and readily distinguished major regional subdivisions of the developing hypothalamus. By using our developmental dataset, we were able to rapidly annotate previously unidentified clusters from existing scRNA-Seq datasets collected during development and to identify the developmental origins of major neuronal populations of the ventromedial hypothalamus. We further show that our approach can rapidly and comprehensively characterize mutants that have altered hypothalamic patterning, identifying Nkx2.1 as a negative regulator of prethalamic identity. These data serve as a resource for further studies of hypothalamic development, physiology, and dysfunction.


Assuntos
Diferenciação Celular , Hipotálamo , Neurônios/metabolismo , Fator Nuclear 1 de Tireoide/metabolismo , Animais , Sequência de Bases , Padronização Corporal , Regulação da Expressão Gênica no Desenvolvimento , Hipotálamo/citologia , Hipotálamo/embriologia , Hipotálamo/crescimento & desenvolvimento , Hipotálamo/metabolismo , Camundongos , Mutação , Análise de Célula Única , Fator Nuclear 1 de Tireoide/genética
9.
PLoS One ; 12(5): e0177451, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28542215

RESUMO

ACE inhibitors are considered first line of treatment in patients with many forms of chronic kidney disease (CKD). Other antihypertensives such as calcium channel blockers achieve similar therapeutic effectiveness in attenuating hypertension-related renal damage progression. Our objective was to explore the value of positron emission tomography (PET) imaging of renal AT1 receptor (AT1R) to guide therapy in the 5/6 subtotal-nephrectomy (Nx) rat model of CKD. Ten weeks after Nx, Sprague-Dawley rats were administered 10mg/kg/d enalapril (NxE), 30mg/kg/d diltiazem (NxD) or left untreated (Nx) for an additional 8-10 weeks. Kidney AT1R expression was assessed using in vivo [18F]fluoropyridine-losartan PET and in vitro autoradiography. Compared to shams, Nx rats exhibited higher systolic blood pressure that was reduced by both enalapril and diltiazem. At 18-20 weeks, plasma creatinine and albuminuria were significantly increased in Nx, reduced to sham levels in NxE, but enhanced in NxD rats. Enalapril treatment decreased kidney angiotensin II whereas diltiazem induced significant elevations in plasma and kidney levels. Reduced PET renal AT1R levels in Nx were normalized by enalapril but not diltiazem, and results were supported by autoradiography. Reduction of renal blood flow in Nx was restored by enalapril, while no difference was observed in myocardial blood flow amongst groups. Enhanced left ventricle mass in Nx was not reversed by enalapril but was augmented with diltiazem. Stroke volume was diminished in untreated Nx compared to shams and restored with both therapies. [18F]Fluoropyridine-Losartan PET allowed in vivo quantification of kidney AT1R changes associated with progression of CKD and with various pharmacotherapies.


Assuntos
Progressão da Doença , Enalapril/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Rim/efeitos dos fármacos , Tomografia por Emissão de Pósitrons , Receptor Tipo 1 de Angiotensina/metabolismo , Insuficiência Renal Crônica/tratamento farmacológico , Angiotensina II/sangue , Animais , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Diltiazem/farmacologia , Diltiazem/uso terapêutico , Enalapril/uso terapêutico , Coração/efeitos dos fármacos , Coração/fisiopatologia , Rim/metabolismo , Rim/patologia , Rim/fisiopatologia , Masculino , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Fluxo Sanguíneo Regional/efeitos dos fármacos , Insuficiência Renal Crônica/diagnóstico por imagem , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/fisiopatologia
11.
EJNMMI Res ; 6(1): 55, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27339045

RESUMO

BACKGROUND: Significant renal mass reduction induced by 5/6 subtotal nephrectomy (Nx) is associated with a chain of events that culminates in hypertension and chronic kidney disease (CKD). Numerous studies have provided evidence for the role of angiotensin (Ang) II type 1 receptor (AT1R) in the promotion and progression of the disease; however, conflicting results were reported on intrarenal AT1R levels in CKD models. METHODS: Male Sprague-Dawley rats (n = 26) underwent Nx or sham operations. Animals were scanned at 8-10 weeks post-surgery with PET using the novel AT1R radioligand [(18)F]FPyKYNE-losartan. Radioligand binding was quantified by kidney-to-blood ratio (KBR), standard uptake value (SUV), and distribution volume (DV). After sacrifice, plasma and kidney Ang II levels were measured. Western blot and (125)I-[Sar(1), Ile(8)]Ang II autoradiography were performed to assess AT1R expression. RESULTS: At 8-10 weeks post-surgery, Nx rats developed hypertension, elevated plasma creatinine levels, left ventricle hypertrophy, increased myocardial blood flow (MBF), and reduced Ang II levels compared to shams. PET measurements displayed significant decrease in KBR (29 %), SUV (24 %), and DV (22 %) induced by Nx (p < 0.05), and these findings were confirmed by in vitro assays. CONCLUSIONS: Reduced renal AT1Rs in hypertensive rats measured with [(18)F]FPyKYNE-losartan PET at 8-10 weeks following Nx support further use of this non-invasive approach in longitudinal studies to better understand the AT1R role in CKD progression.

12.
J Nucl Med ; 57(10): 1612-1617, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27199365

RESUMO

Most physiologic effects of the renin angiotensin system (RAS) are mediated via the angiotensin (Ang) type 1 receptor (AT1R). The 18F-FPyKYNE derivative of the clinically used AT1R blocker losartan exhibits high binding selectivity for kidney AT1R and rapid metabolism in rats. The aim of this study was to further assess the binding profile of this novel PET agent for imaging AT1R in rats and pigs. METHODS: In vitro binding assays were performed with 18F-FPyKYNE-losartan in rat kidneys. Male Sprague-Dawley rats were used to assess dosimetry, antagonistic efficacy via blood pressure measurements, and presence of labeled metabolites in kidneys. Test-retest PET imaging, blocking with AT1R antagonist candesartan (10 mg/kg), and plasma metabolism analysis were performed in female Yorkshire pigs. RESULTS: 18F-FPyKYNE-losartan bound with high affinity (dissociation constant of 49.4 ± 18.0 nM and maximal binding of 348 ± 112 fmol/mm2) to rat kidney AT1R. It bound strongly to plasma proteins in rats (97%), and its labeled metabolites displayed minimal interference on renal AT1R binding. FPyKYNE-losartan fully antagonized the Ang II pressor effect, albeit with 4-fold potency reduction (the effective dose inhibiting 50% of the Ang II-induced maximal pressor response of 25.5 mg/kg) relative to losartan. PET imaging exhibited high kidney-to-blood contrast and slow renal clearance, with an SUV of 14.1 ± 6.2. Excellent reproducibility was observed in the calculated test-retest variability (7.2% ± 0.75%). Only hydrophilic-labeled metabolites were present in plasma samples, and renal retention was reduced (-60%) at 10-15 min after blockade with candesartan. CONCLUSION: 18F-FPyKYNE-losartan has a favorable binding profile and displays high potential for translational work in humans as an AT1R PET imaging agent.


Assuntos
Radioisótopos de Flúor , Losartan/química , Oligopeptídeos/química , Tomografia por Emissão de Pósitrons/métodos , Receptor Tipo 1 de Angiotensina/metabolismo , Animais , Feminino , Losartan/farmacocinética , Masculino , Radiometria , Ratos , Ratos Sprague-Dawley , Suínos , Distribuição Tecidual
13.
Nucl Med Biol ; 42(11): 850-7, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26300209

RESUMO

INTRODUCTION: The angiotensin II type 1 receptor (AT1R) is responsible for the main effects of the renin-angiotensin system (RAS), and its expression pattern is altered in several diseases. The [(11)C]methylated derivatives of the clinically used AT1R blocker (ARB) losartan and its active metabolite EXP3174, that binds with higher affinity to AT1R, were evaluated as potential PET imaging tracers in rat kidneys. METHODS: [(11)C]Methyl-losartan and [(11)C]methyl-EXP3174 were synthesized by [(11)C]methylation of the tetrazole-protected analogs using [11C]methyl iodide. Tissue uptake and binding selectivity of [(11)C]methyl-losartan were assessed by ex-vivo biodistribution and in-vitro autoradiography. Radiolabeled metabolites in rat plasma and kidneys were analysed by column-switch HPLC. Both tracers were evaluated with small animal PET imaging. Due to better pharmacokinetics, [(11)C]methyl-EXP3174 was further investigated via PET by co-injection with AT1R antagonist candesartan or the AT2R antagonist PD123,319. RESULTS: Binding selectivity to renal AT1 over AT2 and Mas receptors was demonstrated for [(11)C]methyl-losartan. Plasma metabolite analysis at 10 min revealed stability of [(11)C]methyl-losartan and [(11)C]methyl-EXP3174 with the presence of unchanged tracer at 70.8 ± 9.9% and 81.4 ± 6.0%, of total radioactivity, respectively. Contrary to [(11)C]methyl-losartan, co-injection of candesartan with [(11)C]methyl-EXP3174 reduced the proportion of unchanged tracer (but not metabolites), indicating that these metabolites do not bind to AT1R in rat kidneys. MicroPET images for both radiotracers displayed high kidney-to-background contrast. Candesartan significantly reduced [(11)C]methyl-EXP3174 uptake in the kidney, whereas no difference was observed following PD123,319 indicating binding selectivity for AT1R. CONCLUSIONS: [(11)C]Methyl-EXP3174 displayed a favorable binding profile compared to [(11)C]methyl-losartan for imaging renal AT1Rs supporting further studies to assess its full potential as a quantitative probe for AT1R via PET.


Assuntos
Radioisótopos de Carbono , Imidazóis/química , Rim/diagnóstico por imagem , Rim/metabolismo , Losartan/química , Tomografia por Emissão de Pósitrons/métodos , Receptor Tipo 1 de Angiotensina/metabolismo , Tetrazóis/química , Animais , Imidazóis/farmacocinética , Losartan/farmacocinética , Masculino , Radioquímica , Ratos , Ratos Sprague-Dawley , Tetrazóis/farmacocinética , Distribuição Tecidual
14.
Nucl Med Biol ; 40(2): 252-61, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23352346

RESUMO

INTRODUCTION: Angiotensin II type 1 (AT(1)) receptors play a key role in the regulation of renal and cardiovascular functions and have been implicated in the pathogenesis of many diseases. The aim of this study was to assess binding of the novel radioligand [(11)C]methyl-candesartan to AT(1) receptors in the rat kidney in vivo with PET. METHODS: Dynamic PET images were acquired for 60 min at baseline, with coinjection of candesartan (5 mg/kg), and after injection of PD123,319 (5 mg/kg). Volumes of distribution (R(C)∙V(T)) were estimated with a two-compartment model, by Logan analysis, and by taking the tissue-to-plasma activity ratio at 50-60 min post-injection. RESULTS: The two-compartment model did not describe the kinetics at baseline adequately and the baseline scans were too short to obtain accurate estimates of R(C)∙V(T) with the Logan approach. Based on the tissue-to-plasma ratios, roughly one-third of V(T) at baseline could be attributed to AT(1) receptor binding. There were no indications of AT(2) receptor binding in the rat kidney. CONCLUSION: It may be possible to detect changes in AT(1) receptor density in the rat kidney in vivo with [(11)C]methyl-candesartan and PET. Imaging AT(1) receptors with PET may provide valuable information on the role of these receptors in the pathogenesis of diseases such as hypertension, diabetic nephropathy, ventricular remodeling, and heart failure.


Assuntos
Benzimidazóis/metabolismo , Rim/diagnóstico por imagem , Rim/metabolismo , Tomografia por Emissão de Pósitrons , Receptor Tipo 1 de Angiotensina/metabolismo , Tetrazóis/metabolismo , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Animais , Benzimidazóis/sangue , Compostos de Bifenilo , Radioisótopos de Carbono , Imidazóis/farmacologia , Rim/efeitos dos fármacos , Cinética , Masculino , Modelos Biológicos , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Tetrazóis/sangue
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