Increased Binding of Peripheral Benzodiazepine Receptor in Alzheimer's Disease Measured by Positron Emission Tomography with [C-11]DAA1106

Clinical Neuroimaging Section, Department of Molecular Neuroimaging, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan.
Biological psychiatry (Impact Factor: 9.47). 06/2008; 64(10):835-41. DOI: 10.1016/j.biopsych.2008.04.021
Source: PubMed

ABSTRACT Peripheral benzodiazepine receptor (PBR) in the brain of Alzheimer's disease (AD) patients has been discussed in relation to the role of gliosis in AD. The PBR was shown to have the ability to reflect activated glial cells, including microglia. The role of activated microglia in AD is an important topic in the pathophysiology of AD. The aim of this study was to quantify PBR in AD brain with a new high-sensitive PBR ligand, [(11)C]DAA1106.
Positron emission tomography (PET) scans with [(11)C]DAA1106, a potent and selective ligand for PBR, were performed on 10 patients with AD and 10 age-matched control subjects. All patients had mild to moderate dementia. Duration of illness was 1-3 years at the time of the scans. The PBR binding in the regions of interest was quantified by binding potential (BP) obtained from compartmental model analysis with plasma input function.
Mean BP was increased in the brain of AD patients compared with control subjects in all measured regions. Statistical significance reached across many of the regions examined, including dorsal and medial prefrontal cortex, lateral temporal cortex, parietal cortex, occipital cortex, anterior cingulate cortex, striatum, and cerebellum.
The broad increase of PBR binding measured with [(11)C]DAA1106 in the brain of AD patients suggests a widespread existence of cellular reactions with PBR in relatively early-stage AD.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Alzheimer's disease (AD), dementia with Lewy bodies, frontotemporal dementia (FTD), and Huntington's disease (HD) are the main neurodegenerative causes of dementia. Causes and mechanisms of these diseases remain elusive. Neuroinflammation is increasingly emerging as an important pathological factor in their development. Positron emission tomography (PET) using [11C]PK11195 represents a method of visualizing the microglial component of neuroinflammation via the translocator protein (TSPO) and we discuss the valuable insights this has yielded in neurodegenerative diseases. We discuss the limitations of this method and the development of second generation TSPO PET ligands which hope to overcome these limitations. We also discuss other methods of visualizing neuroinflammation and review the state of current dementia treatments targeted at neuroinflammation. It is our view that a multimodal investigation into neuroinflammation in AD, Parkinson's disease dementia, FTD and HD will yield valuable pathological insights which will usefully inform development of therapeutic targets and biomarkers.
    Alzheimer's and Dementia 11/2014; DOI:10.1016/j.jalz.2014.08.105 · 17.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In an effort to develop a new SPECT imaging agent for the translocator protein (TSPO), a series of novel iodinated quinoline-2-carboxamides have been synthesised and evaluated for binding affinity using rat brain homogenates. The outcome of the biological testing in combination with HPLC determination of the physicochemical properties of these compounds directed the design of new analogues resulting in 4-(2-iodophenyl)quinoline-2-N-diethylcarboxamide, a new TSPO ligand with higher affinity than the widely used clinical imaging agent PK11195.
    Medicinal Chemistry Communication 11/2013; 4(11):1461. DOI:10.1039/c3md00249g · 2.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Imaging of the 18-kDa translocator protein (TSPO) is a potential tool for examining microglial activation and neuroinflammation in early Alzheimer's disease (AD). [(18)F]FEMPA is a novel high-affinity second-generation TSPO radioligand that has displayed suitable pharmacokinetic properties in preclinical studies. The aims of this study were to quantify the binding of [(18)F]FEMPA to TSPO in AD patients and controls and to investigate whether higher [(18)F]FEMPA binding in AD patients than in controls could be detected in vivo. Ten AD patients (five men, five women; age 66.9 ± 7.3 years; MMSE score 25.5 ± 2.5) and seven controls (three men, four women; age 63.7 ± 7.2 years, MMSE score 29.3 ± 1.0) were studied using [(18)F]FEMPA at Turku (13 subjects) and at Karolinska Institutet (4 subjects). The in vitro binding affinity for TSPO was assessed using PBR28 in a competition assay with [(3)H]PK11195 in seven controls and eight AD patients. Cortical and subcortical regions of interest were examined. Quantification was performed using a two-tissue compartment model (2TCM) and Logan graphical analysis (GA). The outcome measure was the total distribution volume (V T). Repeated measures analysis of variance was used to assess the effect of group and TSPO binding status on V T. Five AD patients and four controls were high-affinity binders (HABs). Three AD patients and three controls were mixed-affinity binders. V T estimated with Logan GA was significantly correlated with V T estimated with the 2TCM in both controls (r = 0.97) and AD patients (r = 0.98) and was selected for the final analysis. Significantly higher V T was found in the medial temporal cortex in AD patients than in controls (p = 0.044) if the TSPO binding status was entered as a covariate. If only HABs were included, significantly higher V T was found in the medial and lateral temporal cortex, posterior cingulate, caudate, putamen, thalamus and cerebellum in AD patients than in controls (p < 0.05). [(18)F]FEMPA seems to be a suitable radioligand for detecting increased TSPO binding in AD patients if their binding status is taken into account.
    European journal of nuclear medicine and molecular imaging 11/2014; 42(3). DOI:10.1007/s00259-014-2955-8 · 5.22 Impact Factor


Available from
Jul 24, 2014