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1.
Mol Psychiatry ; 2024 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-38997465

RESUMO

Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.

2.
Mol Psychiatry ; 28(2): 801-809, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36434055

RESUMO

Autism spectrum disorder (ASD) is a neurodevelopmental disorder whose pathophysiological mechanisms are still unclear. Hypotheses suggest a role for glutamate dysfunctions in ASD development, but clinical studies investigating brain and peripheral glutamate levels showed heterogenous results leading to hypo- and hyper-glutamatergic hypotheses of ASD. Recently, studies proposed the implication of elevated mGluR5 densities in brain areas in the pathophysiology of ASD. Thus, our objective was to characterize glutamate dysfunctions in adult subjects with ASD by quantifying (1) glutamate levels in the cingulate cortex and periphery using proton magnetic resonance spectroscopy and metabolomics, and (2) mGluR5 brain density in this population and in a validated animal model of ASD (prenatal exposure to valproate) at developmental stages corresponding to childhood and adolescence in humans using positron emission tomography. No modifications in cingulate Glu levels were observed between individuals with ASD and controls further supporting the difficulty to evaluate modifications in excitatory transmission using spectroscopy in this population, and the complexity of its glutamate-related changes. Our imaging results showed an overall increased density in mGluR5 in adults with ASD, that was only observed mostly subcortically in adolescent male rats prenatally exposed to valproic acid, and not detected in the stage corresponding to childhood in the same animals. This suggest that clinical changes in mGluR5 density could reflect the adaptation of the glutamatergic dysfunctions occurring earlier rather than being key to the pathophysiology of ASD.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Humanos , Gravidez , Feminino , Adolescente , Adulto , Masculino , Ratos , Animais , Criança , Ácido Glutâmico , Encéfalo , Ácido Valproico , Sinapses
3.
Eur J Med Chem ; 244: 114794, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36252395

RESUMO

Age-related neurodegenerative diseases have in common the occurrence of cognitive impairment, a highly incapacitating process that involves the cholinergic neurotransmission system. The vesicular acetylcholine transporter (VAChT) positron emission tomography (PET) tracer [18F]fluoroethoxybenzovesamicol ((-)-[18F]FEOBV) has recently demonstrated its high value to detect alterations of the cholinergic system in Alzheimer's disease, Parkinson's disease and dementia with Lewy body. We present here the development of the new vesamicol derivative tracer (-)-(R,R)-5-[18F]fluorobenzovesamicol ((-)[18F]FBVM) that we compared to (-)[18F]FEOBV in the same experimental conditions. We show that: i) in vitro affinity for the VAChT was 50-fold higher for (-)FBVM (Ki = 0.9 ± 0.3 nM) than for (-)FEOBV (Ki = 61 ± 2.8 nM); ii) in vivo in rats, a higher signal-to-noise specific brain uptake and a lower binding to plasma proteins and peripheral defluorination were obtained for (-)[18F]FBVM compared to (-)[18F]FEOBV. Our findings demonstrate that (-)[18F]FBVM is a highly promising PET imaging tracer which could be sufficiently sensitive to detect in humans the cholinergic denervation that occurs in brain areas having a low density of VAChT such as the cortex and hippocampus.


Assuntos
Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X , Humanos , Animais , Ratos , Proteínas Vesiculares de Transporte de Acetilcolina/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Colinérgicos
4.
Front Physiol ; 13: 881674, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35928559

RESUMO

Preterm birth before the gestational age of 32 weeks is associated with the occurrence of specific white matter damage (WMD) that can compromise the neurological outcome. These white matter abnormalities are embedded in more global brain damage defining the encephalopathy of prematurity (EoP). A global reduction in white matter volume that corresponds to chronic diffuse WMD is the most frequent form in contemporary cohorts of very preterm infants. This WMD partly results from alterations of the oligodendrocyte (OL) lineage during the vulnerability window preceding the beginning of brain myelination. The occurrence of prenatal, perinatal and postnatal events in addition to preterm birth is related to the intensity of WMD. Systemic inflammation is widely recognised as a risk factor of WMD in humans and in animal models. This review reports the OL lineage alterations associated with the WMD observed in infants suffering from EoP and emphasizes the role of systemic inflammation in inducing these alterations. This issue is addressed through data on human tissue and imaging, and through neonatal animal models that use systemic inflammation to induce WMD. Interestingly, the OL lineage damage varies according to the inflammatory stimulus, i.e., the liposaccharide portion of the E.Coli membrane (LPS) or the proinflammatory cytokine Interleukin-1ß (IL-1ß). This discrepancy reveals multiple cellular pathways inducible by inflammation that result in EoP. Variable long-term consequences on the white matter morphology and functioning may be speculated upon according to the intensity of the inflammatory challenge. This hypothesis emerges from this review and requires further exploration.

5.
J Cereb Blood Flow Metab ; 42(12): 2216-2229, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-35945692

RESUMO

Despite an apparently silent imaging, some patients with mild traumatic brain injury (TBI) experience cognitive dysfunctions, which may persist chronically. Brain changes responsible for these dysfunctions are unclear and commonly overlooked. It is thus crucial to increase our understanding of the mechanisms linking the initial event to the functional deficits, and to provide objective evidence of brain tissue alterations underpinning these deficits. We first set up a murine model of closed-head controlled cortical impact, which provoked persistent cognitive and sensorimotor deficits, despite no evidence of brain contusion or bleeding on MRI, thus recapitulating features of mild TBI. Molecular MRI for P-selectin, a key adhesion molecule, detected no sign of cerebrovascular inflammation after mild TBI, as confirmed by immunostainings. By contrast, in vivo PET imaging with the TSPO ligand [18F]DPA-714 demonstrated persisting signs of neuroinflammation in the ipsilateral cortex and hippocampus after mild TBI. Interestingly, immunohistochemical analyses confirmed these spatio-temporal profiles, showing a robust parenchymal astrogliosis and microgliosis, at least up to 3 weeks post-injury in both the cortex and hippocampus. In conclusion, we show that even one single mild TBI induces long-term behavioural deficits, associated with a persistent neuro-inflammatory status that can be detected by PET imaging.


Assuntos
Concussão Encefálica , Lesões Encefálicas Traumáticas , Animais , Humanos , Camundongos , Encéfalo , Concussão Encefálica/complicações , Concussão Encefálica/diagnóstico por imagem , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/diagnóstico por imagem , Modelos Animais de Doenças , Doenças Neuroinflamatórias , Tomografia por Emissão de Pósitrons/métodos , Receptores de GABA
6.
Sci Rep ; 11(1): 22167, 2021 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-34773065

RESUMO

Melatonin has shown promising neuroprotective effects due to its anti-oxidant, anti-inflammatory and anti-apoptotic properties, making it a candidate drug for translation to humans in conditions that compromise the developing brain. Our study aimed to explore the impact of prenatal melatonin in an inflammatory/infectious context on GABAergic neurons and on oligodendrocytes (OLs), key cells involved in the encephalopathy of prematurity. An inflammatory/infectious agent (LPS, 300 µg/kg) was injected intraperitoneally (i.p.) to pregnant Wistar rats at gestational day 19 and 20. Melatonin (5 mg/kg) was injected i.p. following the same schedule. Immunostainings focusing on GABAergic neurons, OL lineage and myelination were performed on pup brain sections. Melatonin succeeded in preventing the LPS-induced decrease of GABAergic neurons within the retrospenial cortex, and sustainably promoted GABAergic neurons within the dentate gyrus in the inflammatory/infectious context. However, melatonin did not effectively prevent the LPS-induced alterations on OLs and myelination. Therefore, we demonstrated that melatonin partially prevented the deleterious effects of LPS according to the cell type. The timing of exposure related to the cell maturation stage is likely to be critical to achieve an efficient action of melatonin. Furthermore, it can be speculated that melatonin exerts a modest protective effect on extremely preterm infant brains.


Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/embriologia , Corioamnionite/patologia , Melatonina/farmacologia , Neurogênese/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Animais , Animais Recém-Nascidos , Anti-Inflamatórios/farmacologia , Corioamnionite/etiologia , Corioamnionite/metabolismo , Corioamnionite/prevenção & controle , Citocinas/metabolismo , Modelos Animais de Doenças , Suscetibilidade a Doenças , Feminino , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Substância Cinzenta/efeitos dos fármacos , Substância Cinzenta/metabolismo , Substância Cinzenta/patologia , Lipopolissacarídeos/efeitos adversos , Oligodendroglia/efeitos dos fármacos , Oligodendroglia/metabolismo , Gravidez , Ratos
7.
Theranostics ; 11(14): 6644-6667, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34093845

RESUMO

Mouse models of Alzheimer's disease (AD) are valuable but do not fully recapitulate human AD pathology, such as spontaneous Tau fibril accumulation and neuronal loss, necessitating the development of new AD models. The transgenic (TG) TgF344-AD rat has been reported to develop age-dependent AD features including neuronal loss and neurofibrillary tangles, despite only expressing APP and PSEN1 mutations, suggesting an improved modelling of AD hallmarks. Alterations in neuronal networks as well as learning performance and cognition tasks have been reported in this model, but none have combined a longitudinal, multimodal approach across multiple centres, which mimics the approaches commonly taken in clinical studies. We therefore aimed to further characterise the progression of AD-like pathology and cognition in the TgF344-AD rat from young-adults (6 months (m)) to mid- (12 m) and advanced-stage (18 m, 25 m) of the disease. Methods: TgF344-AD rats and wild-type (WT) littermates were imaged at 6 m, 12 m and 18 m with [18F]DPA-714 (TSPO, neuroinflammation), [18F]Florbetaben (Aß) and [18F]ASEM (α7-nicotinic acetylcholine receptor) and with magnetic resonance spectroscopy (MRS) and with (S)-[18F]THK5117 (Tau) at 15 and 25 m. Behaviour tests were also performed at 6 m, 12 m and 18 m. Immunohistochemistry (CD11b, GFAP, Aß, NeuN, NeuroChrom) and Tau (S)-[18F]THK5117 autoradiography, immunohistochemistry and Western blot were also performed. Results: [18F]DPA-714 positron emission tomography (PET) showed an increase in neuroinflammation in TG vs wildtype animals from 12 m in the hippocampus (+11%), and at the advanced-stage AD in the hippocampus (+12%), the thalamus (+11%) and frontal cortex (+14%). This finding coincided with strong increases in brain microgliosis (CD11b) and astrogliosis (GFAP) at these time-points as assessed by immunohistochemistry. In vivo [18F]ASEM PET revealed an age-dependent increase uptake in the striatum and pallidum/nucleus basalis of Meynert in WT only, similar to that observed with this tracer in humans, resulting in TG being significantly lower than WT by 18 m. In vivo [18F]Florbetaben PET scanning detected Aß accumulation at 18 m, and (S)-[18F]THK5117 PET revealed subsequent Tau accumulation at 25m in hippocampal and cortical regions. Aß plaques were low but detectable by immunohistochemistry from 6 m, increasing further at 12 and 18 m with Tau-positive neurons adjacent to Aß plaques at 18 m. NeuroChrom (a pan neuronal marker) immunohistochemistry revealed a loss of neuronal staining at the Aß plaques locations, while NeuN labelling revealed an age-dependent decrease in hippocampal neuron number in both genotypes. Behavioural assessment using the novel object recognition task revealed that both WT & TgF344-AD animals discriminated the novel from familiar object at 3 m and 6 m of age. However, low levels of exploration observed in both genotypes at later time-points resulted in neither genotype successfully completing the task. Deficits in social interaction were only observed at 3 m in the TgF344-AD animals. By in vivo MRS, we showed a decrease in neuronal marker N-acetyl-aspartate in the hippocampus at 18 m (-18% vs age-matched WT, and -31% vs 6 m TG) and increased Taurine in the cortex of TG (+35% vs age-matched WT, and +55% vs 6 m TG). Conclusions: This multi-centre multi-modal study demonstrates, for the first time, alterations in brain metabolites, cholinergic receptors and neuroinflammation in vivo in this model, validated by robust ex vivo approaches. Our data confirm that, unlike mouse models, the TgF344-AD express Tau pathology that can be detected via PET, albeit later than by ex vivo techniques, and is a useful model to assess and longitudinally monitor early neurotransmission dysfunction and neuroinflammation in AD.


Assuntos
Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/metabolismo , Espectroscopia de Ressonância Magnética , Placa Amiloide/metabolismo , Tomografia por Emissão de Pósitrons , Proteínas tau/metabolismo , Envelhecimento/metabolismo , Envelhecimento/fisiologia , Doença de Alzheimer/patologia , Animais , Escala de Avaliação Comportamental , Disfunção Cognitiva/genética , Disfunção Cognitiva/fisiopatologia , Modelos Animais de Doenças , Feminino , Radioisótopos de Flúor , Lobo Frontal/metabolismo , Lobo Frontal/patologia , Gliose/metabolismo , Hipocampo/metabolismo , Hipocampo/patologia , Imuno-Histoquímica , Inflamação/metabolismo , Locomoção/genética , Locomoção/fisiologia , Masculino , Neurônios/metabolismo , Neurônios/patologia , Ratos , Ratos Transgênicos , Receptores Colinérgicos/metabolismo , Tálamo/metabolismo , Tálamo/patologia
8.
J Labelled Comp Radiopharm ; 64(9): 363-372, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34089268

RESUMO

We synthesized 5-[18 F]-fluoro-1H-indol-2-yl)(4-methyl-1-piperazinyl)methanone ([18 F]5) via a Suzuki approach starting from a protected pinacol borane precursor followed by acidic hydrolysis of the t-Boc protecting group. The non-optimized radiochemical yield was 5.7 ± 1.35%, radiochemical purity was over 99%, and molar activity was 100.7 ± 34.5 GBq/µmol (n = 3). [18 F]5 was stable in rat plasma for at least 4 h and was evaluated by µPET imaging and biodistribution using a unilateral quinolinic acid rat model of neuroinflammation. The time-activity curve showed that [18 F]5 entered the brain immediately after intravenous injection and then left it progressively with a very low level reached from 30 min after injection. The biodistribution study showed no difference in the accumulation of [18 F]5 between the lesioned and intact side of the brain and between control rats and animals pretreated with a saturating dose of JNJ-7777120 as a specific H4R antagonist. Hence, despite its in vitro nanomolar affinity for H4R, and its ability to cross the blood-brain barrier in rats, [18 F]5 does not appear suitable to image in vivo the receptor by PET.


Assuntos
Receptores Histamínicos H4
9.
Transl Psychiatry ; 11(1): 66, 2021 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-33473111

RESUMO

Altered glutamate signaling is thought to be involved in a myriad of psychiatric disorders. Positron emission tomography (PET) imaging with [18F]FPEB allows assessing dynamic changes in metabotropic glutamate receptor 5 (mGluR5) availability underlying neuropathological conditions. The influence of endogenous glutamatergic levels into receptor binding has not been well established yet. The purpose of this study was to explore the [18F]FPEB binding regarding to physiological fluctuations or acute changes of glutamate synaptic concentrations by a translational approach; a PET/MRS imaging study in 12 healthy human volunteers combined to a PET imaging after an N-acetylcysteine (NAc) pharmacological challenge in rodents. No significant differences were observed with small-animal PET in the test and retest conditions on the one hand and the NAc condition on the other hand for any regions. To test for an interaction of mGuR5 density and glutamatergic concentrations in healthy subjects, we correlated the [18F]FPEB BPND with Glu/Cr, Gln/Cr, Glx/Cr ratios in the anterior cingulate cortex VOI; respectively, no significance correlation has been revealed (Glu/Cr: r = 0.51, p = 0.09; Gln/Cr: r = -0.46, p = 0.13; Glx/Cr: r = -0.035, p = 0.92).These data suggest that the in vivo binding of [18F]FPEB to an allosteric site of the mGluR5 is not modulated by endogenous glutamate in vivo. Thus, [18F]FPEB appears unable to measure acute fluctuations in endogenous levels of glutamate.


Assuntos
Acetilcisteína , Receptor de Glutamato Metabotrópico 5 , Animais , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Voluntários Saudáveis , Humanos , Tomografia por Emissão de Pósitrons , Piridinas , Compostos Radiofarmacêuticos , Ratos , Receptor de Glutamato Metabotrópico 5/metabolismo
10.
Fundam Clin Pharmacol ; 35(3): 582-594, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33484165

RESUMO

Alzheimer's disease (AD) leads to the progressive loss of memory and other cognitive functions. It is the most common form of dementia in the elderly and has become a major public health problem due to the increase in life expectancy. Although the detection of AD is based on several neuropsychological tests, imaging, and biological analyses, none of these biomarkers allows a clear understanding of the pathophysiological mechanisms involved in the disease, and no efficient treatment is currently available. Metabolomics, which allows the study of biochemical alterations underlying pathological processes, could help to identify these mechanisms, to discover new therapeutic targets, and to monitor the therapeutic response and disease progression. In this review, we have summarized and analyzed the results from a number of studies on metabolomics analyses performed in biological samples originated from the central nervous system, in AD subjects, and in animal models of this disease. This synthesis revealed modified expression of specific metabolites in pathological conditions which allowed the identification of significantly impacted metabolic pathways both in animals and humans, such as the arginine biosynthesis and the alanine, aspartate, and glutamate metabolism. We discuss the potential biochemical mechanisms involved, the extent to which they could impact the specific hallmarks of AD, and the therapeutic approaches which could be proposed as a result.


Assuntos
Doença de Alzheimer/fisiopatologia , Metabolômica/métodos , Alanina/metabolismo , Doença de Alzheimer/tratamento farmacológico , Animais , Arginina/biossíntese , Ácido Aspártico/metabolismo , Biomarcadores , Modelos Animais de Doenças , Ácido Glutâmico/metabolismo , Humanos , Ratos
11.
Front Neurosci ; 15: 803927, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35069106

RESUMO

In a previous study, we showed that viniferin decreased amyloid deposits and reduced neuroinflammation in APPswePS1dE9 transgenic mice between 3 and 6 months of age. In the present study, wild type and APPswePS1dE9 transgenic mice were treated from 7 to 11 or from 3 to 12 months by a weekly intraperitoneal injection of either 20 mg/kg viniferin or resveratrol or their vehicle, the polyethylene glycol 200 (PEG 200). The cognitive status of the mice was evaluated by the Morris water maze test. Then, amyloid burden and neuroinflammation were quantified by western-blot, Enzyme-Linked ImmunoSorbent Assay (ELISA), immunofluorescence, and in vivo micro-Positon Emission Tomography (PET) imaging. Viniferin decreased hippocampal amyloid load and deposits with greater efficiency than resveratrol, and both treatments partially prevented the cognitive decline. Furthermore, a significant decrease in brain uptake of the TSPO PET tracer [18F]DPA-714 was observed with viniferin compared to resveratrol. Expression of GFAP, IBA1, and IL-1ß were decreased by viniferin but PEG 200, which was very recently shown to be a neuroinflammatory inducer, masked the neuroprotective power of viniferin.

12.
Neural Regen Res ; 16(6): 1099-1104, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33269756

RESUMO

To date there is no treatment able to stop or slow down the loss of dopaminergic neurons that characterizes Parkinson's disease. It was recently observed in a rodent model of Alzheimer's disease that the interaction between the a7 subtype of nicotinic acetylcholine receptor (a7-nAChR) and sigma-1 receptor (s1-R) could exert neuroprotective effects through the modulation of neuroinflammation which is one of the key components of the pathophysiology of Parkinson's disease. In this context, the aim of the present study was to assess the effects of the concomitant administration of N-(3R)-1-azabicyclo[2.2.2]oct-3-yl-furo[2,3-c]pyridine-5-carboxamide (PHA) 543613 as an a7-nAChR agonist and 2-(4-morpholinethyl) 1-phenylcyclohexanecarboxylate (PRE)-084 as a s1-R agonist in a well-characterized 6-hydroxydopamine rat model of Parkinson's disease. The animals received either vehicle separately or the dual therapy PHA/PRE once a day until day 14 post-lesion. Although no effect was noticed in the amphetamine-induced rotation test, our data has shown that the PHA/PRE treatment induced partial protection of the dopaminergic neurons (15-20%), assessed by the dopamine transporter density in the striatum and immunoreactive tyrosine hydroxylase in the substantia nigra. Furthermore, this dual therapy reduced the degree of glial activation consecutive to the 6-hydroxydopamine lesion, i.e, the 18 kDa translocation protein density and glial fibrillary acidic protein staining in the striatum, and the CD11b and glial fibrillary acidic protein staining in the substantia nigra. Hence, this study reports for the first time that concomitant activation of a7-nAChR and s1-R can provide a partial recovery of the nigro-striatal dopaminergic neurons through the modulation of microglial activation. The study was approved by the Regional Ethics Committee (CEEA Val de Loire n°19) validated this protocol (Authorization N°00434.02) on May 15, 2014.

13.
Eur J Nucl Med Mol Imaging ; 47(11): 2589-2601, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32211931

RESUMO

Longitudinal mouse PET imaging is becoming increasingly popular due to the large number of transgenic and disease models available but faces challenges. These challenges are related to the small size of the mouse brain and the limited spatial resolution of microPET scanners, along with the small blood volume making arterial blood sampling challenging and impossible for longitudinal studies. The ability to extract an input function directly from the image would be useful for quantification in longitudinal small animal studies where there is no true reference region available such as TSPO imaging. METHODS: Using dynamic, whole-body 18F-DPA-714 PET scans (60 min) in a mouse model of hippocampal sclerosis, we applied a factor analysis (FA) approach to extract an image-derived input function (IDIF). This mouse-specific IDIF was then used for 4D-resolution recovery and denoising (4D-RRD) that outputs a dynamic image with better spatial resolution and noise properties, and a map of the total volume of distribution (VT) was obtained using a basis function approach in a total of 9 mice with 4 longitudinal PET scans each. We also calculated percent injected dose (%ID) with and without 4D-RRD. The VT and %ID parameters were compared to quantified ex vivo autoradiography using regional correlations of the specific binding from autoradiography against VT and %ID parameters. RESULTS: The peaks of the IDIFs were strongly correlated with the injected dose (Pearson R = 0.79). The regional correlations between the %ID estimates and autoradiography were R = 0.53 without 4D-RRD and 0.72 with 4D-RRD over all mice and scans. The regional correlations between the VT estimates and autoradiography were R = 0.66 without 4D-RRD and 0.79 with application of 4D-RRD over all mice and scans. CONCLUSION: We present a FA approach for IDIF extraction which is robust, reproducible and can be used in quantification methods for resolution recovery, denoising and parameter estimation. We demonstrated that the proposed quantification method yields parameter estimates closer to ex vivo measurements than semi-quantitative methods such as %ID and is immune to tracer binding in tissue unlike reference tissue methods. This approach allows for accurate quantification in longitudinal PET studies in mice while avoiding repeated blood sampling.


Assuntos
Algoritmos , Tomografia por Emissão de Pósitrons , Animais , Modelos Animais de Doenças , Camundongos
14.
Mol Imaging Biol ; 22(2): 348-357, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31286348

RESUMO

PURPOSE: The nicotinic acetylcholine alpha-7 receptors (α7R) are involved in a number of neuropsychiatric and neurodegenerative brain disorders such as Parkinson's disease (PD). However, their specific pathophysiologic roles are still unclear. In this context, we studied the evolution of these receptors in vivo by positron emission tomography (PET) imaging using the recently developed tracer 3-(1,4-diazabicyclo[3.2.2]nonan-4-yl)-6-[18F]fluorodibenzo[b,d]thiophene-5,5-dioxide) in a rat model mimicking early stages of PD. PROCEDURES: PET imaging of α7R was performed at 3, 7, and 14 days following a partial striatal unilateral lesion with 6-hydroxydopamine in adult rats. After the last imaging experiments, the status of nigro-striatal dopamine neurons as well as different markers of neuroinflammation was evaluated on brain sections by autoradiographic and immunofluorescent experiments. RESULTS: We showed an early and transitory rise in α7R expression in the lesioned striatum and substantia nigra, followed by over-expression of several gliosis activation markers in these regions of interest. CONCLUSIONS: These findings support a longitudinally follow-up of α7R in animal models of PD and highlight the requirement to use a potential neuroprotective approach through α7R ligands at the early stages of PD.


Assuntos
Encéfalo/diagnóstico por imagem , Doença de Parkinson/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Receptor Nicotínico de Acetilcolina alfa7/metabolismo , Anfetaminas/farmacologia , Animais , Autorradiografia , Compostos Azabicíclicos , Mapeamento Encefálico/métodos , Óxidos S-Cíclicos , Modelos Animais de Doenças , Radioisótopos de Flúor , Masculino , Neuroproteção , Compostos Radiofarmacêuticos , Ratos , Ratos Wistar
15.
Eur J Med Chem ; 179: 449-469, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31271958

RESUMO

In this paper we describe the design and synthesis of bis(Het)Aryl-1,2,3-triazole quinuclidine α7R ligands using an efficient three-step sequence including a Suzuki-Miyaura cross coupling reaction with commercially available and home-made boron derivatives. The exploration of SAR required the preparation of uncommon boron derivatives. Forty final drugs were tested for their ability to bind the target and nine of them exhibited Ki values below nanomolar concentrations. The best scores were always obtained when the 5-phenyl-2-thiophenyl core was attached to the triazole. The selectivity of these compounds towards the nicotinic α4ß2 and serotoninergic 5HT3 receptors was assessed and their brain penetration was quantified by the preparation and in vivo evaluation of two [18F] radiolabelled derivatives. It can be expected from our results that some of these compounds will be suitable for further developments and will have effects on cognitive disorders.


Assuntos
Encéfalo/diagnóstico por imagem , Transtornos Cognitivos/tratamento farmacológico , Radioisótopos de Flúor/química , Marcação por Isótopo , Agonistas Nicotínicos/farmacologia , Tomografia por Emissão de Pósitrons , Quinuclidinas/farmacologia , Triazóis/farmacologia , Receptor Nicotínico de Acetilcolina alfa7/agonistas , Animais , Encéfalo/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Transtornos Cognitivos/metabolismo , Relação Dose-Resposta a Droga , Ligantes , Estrutura Molecular , Agonistas Nicotínicos/síntese química , Agonistas Nicotínicos/química , Quinuclidinas/síntese química , Quinuclidinas/química , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Triazóis/síntese química , Triazóis/química , Células Tumorais Cultivadas , Receptor Nicotínico de Acetilcolina alfa7/metabolismo
16.
Front Med (Lausanne) ; 6: 90, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31131278

RESUMO

The membrane dopamine transporter (DAT) is involved in a number of brain disorders and its exploration by positron emission tomography (PET) imaging is highly relevant for the early and differential diagnosis, follow-up and treatment assessment of these diseases. A number of carbon-11 and fluor-18 labeled tracers are to date available for this aim, the majority of them being derived from the chemical structure of cocaine. The development of such a tracer, from its conception to its use, is a long process, the expected result being to obtain the best radiopharmaceutical adapted for clinical protocols. In this context, the cocaine derivative (E)-N-(4-fluorobut-2-enyl)2ß-carbomethoxy-3ß-(4'-tolyl)nortropane, or LBT-999, has passed all the required stages of the development that makes it now a highly relevant imaging tool, particularly in the context of Parkinson's disease. This review describes the different steps of the development of LBT-999 which initially came from its non-fluorinated derivative (E)-N-(3-iodoprop-2-enyl)-2-carbomethoxy-3-(4-methylphenyl) nortropane, or PE2I, because of its high promising properties. [18F]LBT-999 has been extensively characterized in rodent and non-human primate models, in which it demonstrated its capability to explore in vivo the DAT localized at the dopaminergic nerve endings as well as at the mesencephalic cell bodies, in physiological conditions. In lesion-induced rat models of Parkinson's disease, [18F]LBT-999 was able to precisely quantify in vivo the dopaminergic neuron loss, and to assess the beneficial effects of therapeutic approaches such as pharmacological treatment and cell transplantation. Finally recent clinical data demonstrated the efficiency of [18F]LBT-999 in the diagnosis of Parkinson's disease.

17.
Fundam Clin Pharmacol ; 33(5): 544-548, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30866091

RESUMO

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the nigro-striatal pathway. Interestingly, it has already been shown that an intracerebral administration of neuropeptide Y (NPY) decreases the neurodegeneration induced by 6-hydroxydopamine (6-OHDA) in rodents and prevents loss of dopamine (DA) and DA transporter density. The etiology of idiopathic PD now suggest that chronic production of inflammatory mediators by activated microglial cells mediates the majority of DA-neuronal tissue destruction. In an animal experimental model of PD, the present study shows that NPY inhibited the activation of microglia evaluated by the binding of the translocator protein (TSPO) ligand [3H]PK11195 in striatum and substantia nigra of 6-OHDA rats. These results suggest a potential role for inflammation in the pathophysiology of the disease and a potential treatment by NPY in PD.


Assuntos
Inflamação/tratamento farmacológico , Neuropeptídeo Y/farmacologia , Neuroproteção/efeitos dos fármacos , Doença de Parkinson/tratamento farmacológico , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Modelos Animais de Doenças , Dopamina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Inflamação/metabolismo , Masculino , Microglia/efeitos dos fármacos , Microglia/metabolismo , Degeneração Neural/tratamento farmacológico , Degeneração Neural/metabolismo , Oxidopamina/farmacologia , Doença de Parkinson/metabolismo , Ratos , Ratos Wistar , Substância Negra/efeitos dos fármacos , Substância Negra/metabolismo
18.
J Enzyme Inhib Med Chem ; 34(1): 1-7, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30362376

RESUMO

A series of novel derivatives exhibiting high affinity and selectivity towards the COX-2 enzyme in the (aza) indazole series was developed. A short synthetic route involving a bromination/arylation sequence under microwave irradiation and direct C-H activation were established in the indazole and azaindazole series respectively. In vitro assays were conducted and structural modifications were carried out on these scaffolds to furnish compound 16 which exhibited effective COX-2 inhibitory activity, with IC50 values of 0.409 µM and an excellent selectivity versus COX-1. Radiolabeling of this most potent derivative [18F]16 was achieved after boron ester release and the tracer was evaluated in vivo in a rat model of neuroinflammation. All chemistry, radiochemistry and biological experimental data are discussed.


Assuntos
Compostos Aza/farmacologia , Inibidores de Ciclo-Oxigenase 2/farmacologia , Ciclo-Oxigenase 2/metabolismo , Indazóis/farmacologia , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos/farmacologia , Animais , Compostos Aza/síntese química , Compostos Aza/química , Inibidores de Ciclo-Oxigenase 2/síntese química , Inibidores de Ciclo-Oxigenase 2/química , Relação Dose-Resposta a Droga , Radioisótopos de Flúor , Indazóis/síntese química , Indazóis/química , Estrutura Molecular , Traçadores Radioativos , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/química , Ratos , Relação Estrutura-Atividade
19.
Synapse ; 73(3): e22077, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30368914

RESUMO

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic (DA) neurons constituting the nigrostriatal pathway. Neuroinflammation, related to microglial activation, plays an important role in this process. Exploration of animal models of PD using neuroimaging modalities allows to better understand the pathophysiology of the disease. Here, we fully explored a moderate lesion model in the rat in which 6-hydroxydopamine was unilaterally delivered in three sites along the striatum. The degenerative process was assessed through in vivo Positron Emission Tomography (PET) imaging and in vitro autoradiographic quantitation of the striatal dopamine transporter (DAT) and immunostaining of tyrosine hydroxylase (TH). The microglial activation was studied through in vitro autoradiographic quantitation of the 18 kDa translocator protein (TSPO) in the striatum and CD11b staining in the SN. In addition, a targeted metabolomics exploration was performed in both these structures using mass spectrometry coupled to HPLC. Our results showed a reproducible decrease in the striatal DAT density associated with a reduction in the number of TH-positive cells in the SN and striatum, reflecting a robust moderate degeneration of nigrostriatal DA neurons. In addition, we observed strong microglia activation in both the striatum and SN ipsilateral to the lesion, highlighting that this moderate degeneration of DA neurons was associated with a marked neuroinflammation. Our metabolomics studies revealed alterations of specific metabolites and metabolic pathways such as carnitine, arginine/proline, and histidine metabolisms. These results bring new insights in the PD mechanism knowledge and new potential targets for future therapeutic strategies.


Assuntos
Corpo Estriado/patologia , Neurônios Dopaminérgicos/patologia , Oxidopamina/toxicidade , Doença de Parkinson/patologia , Animais , Proteínas de Transporte/metabolismo , Corpo Estriado/diagnóstico por imagem , Corpo Estriado/metabolismo , Modelos Animais de Doenças , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Masculino , Metaboloma , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/patologia , Doença de Parkinson/etiologia , Tomografia por Emissão de Pósitrons , Ratos , Ratos Wistar , Receptores de GABA-A/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo
20.
Neural Regen Res ; 13(4): 737-741, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29722329

RESUMO

Neuroinflammation is a common element involved in the pathophysiology of neurodegenerative diseases. We recently reported that repeated alpha-7 nicotinic acetylcholine receptor (α7nAChR) activations by a potent agonist such as PHA 543613 in quinolinic acid-injured rats exhibited protective effects on neurons. To further investigate the underlying mechanism, we established rat models of early-stage Huntington's disease by injection of quinolinic acid into the right striatum and then intraperitoneally injected 12 mg/kg PHA 543613 or sterile water, twice a day during 4 days. Western blot assay results showed that the expression of heme oxygenase-1 (HO-1), the key component of the cholinergic anti-inflammatory pathway, in the right striatum of rat models of Huntington's disease subjected to intraperitoneal injection of PHA 543613 for 4 days was significantly increased compared to the control rats receiving intraperitoneal injection of sterile water, and that the increase in HO-1 expression was independent of change in α7nAChR expression. These findings suggest that HO-1 expression is unrelated to α7nAChR density and the increase in HO-1 expression likely contributes to α7nAChR activation-related neuroprotective effect in early-stage Huntington's disease.

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