1
|
Shapira R, Gdalyahu A, Gottfried I, Sasson E, Hadanny A, Efrati S, Blinder P, Ashery U. Hyperbaric oxygen therapy alleviates vascular dysfunction and amyloid burden in an Alzheimer's disease mouse model and in elderly patients. Aging (Albany NY) 2021; 13:20935-20961. [PMID: 34499614 PMCID: PMC8457592 DOI: 10.18632/aging.203485] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 08/10/2021] [Indexed: 04/21/2023]
Abstract
Vascular dysfunction is entwined with aging and in the pathogenesis of Alzheimer's disease (AD) and contributes to reduced cerebral blood flow (CBF) and consequently, hypoxia. Hyperbaric oxygen therapy (HBOT) is in clinical use for a wide range of medical conditions. In the current study, we exposed 5XFAD mice, a well-studied AD model that presents impaired cognitive abilities, to HBOT and then investigated the therapeutical effects using two-photon live animal imaging, behavioral tasks, and biochemical and histological analysis. HBOT increased arteriolar luminal diameter and elevated CBF, thus contributing to reduced hypoxia. Furthermore, HBOT reduced amyloid burden by reducing the volume of pre-existing plaques and attenuating the formation of new ones. This was associated with changes in amyloid precursor protein processing, elevated degradation and clearance of Aß protein and improved behavior of 5XFAD mice. Hence, our findings are consistent with the effects of HBOT being mediated partially through a persistent structural change in blood vessels that reduces brain hypoxia. Motivated by these findings, we exposed elderly patients with significant memory loss at baseline to HBOT and observed an increase in CBF and improvement in cognitive performances. This study demonstrates HBOT efficacy in hypoxia-related neurological conditions, particularly in AD and aging.
Collapse
Affiliation(s)
- Ronit Shapira
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Amos Gdalyahu
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Irit Gottfried
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Efrat Sasson
- Sagol Center for Hyperbaric Medicine and Research, Assaf Harofeh Medical Center, Be’er Ya’akov, Israel
| | - Amir Hadanny
- Sagol Center for Hyperbaric Medicine and Research, Assaf Harofeh Medical Center, Be’er Ya’akov, Israel
| | - Shai Efrati
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
- Sackler School of Medicine, Tel Aviv University, Tel-Aviv, Israel
- Sagol Center for Hyperbaric Medicine and Research, Assaf Harofeh Medical Center, Be’er Ya’akov, Israel
| | - Pablo Blinder
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
| |
Collapse
|
2
|
Klohs J. An Integrated View on Vascular Dysfunction in Alzheimer's Disease. NEURODEGENER DIS 2020; 19:109-127. [PMID: 32062666 DOI: 10.1159/000505625] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 12/23/2019] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Cerebrovascular disease is a common comorbidity in patients with Alzheimer's disease (AD). It is believed to contribute additively to the cognitive impairment and to lower the threshold for the development of dementia. However, accumulating evidence suggests that dysfunction of the cerebral vasculature and AD neuropathology interact in multiple ways. Vascular processes even proceed AD neuropathology, implicating a causal role in the etiology of AD. Thus, the review aims to provide an integrated view on vascular dysfunction in AD. SUMMARY In AD, the cerebral vasculature undergoes pronounced cellular, morphological and structural changes, which alters regulation of blood flow, vascular fluid dynamics and vessel integrity. Stiffening of central blood vessels lead to transmission of excessive pulsatile energy to the brain microvasculature, causing end-organ damage. Moreover, a dysregulated hemostasis and chronic vascular inflammation further impede vascular function, where its mediators interact synergistically. Changes of the cerebral vasculature are triggered and driven by systemic vascular abnormalities that are part of aging, and which can be accelerated and aggravated by cardiovascular diseases. Key Messages: In AD, the cerebral vasculature is the locus where multiple pathogenic processes converge and contribute to cognitive impairment. Understanding the molecular mechanism and pathophysiology of vascular dysfunction in AD and use of vascular blood-based and imaging biomarker in clinical studies may hold promise for future prevention and therapy of the disease.
Collapse
Affiliation(s)
- Jan Klohs
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland, .,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland,
| |
Collapse
|
3
|
Govaerts K, Lechat B, Struys T, Kremer A, Borghgraef P, Van Leuven F, Himmelreich U, Dresselaers T. Longitudinal assessment of cerebral perfusion and vascular response to hypoventilation in a bigenic mouse model of Alzheimer's disease with amyloid and tau pathology. NMR IN BIOMEDICINE 2019; 32:e4037. [PMID: 30489666 DOI: 10.1002/nbm.4037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 06/09/2023]
Abstract
Alzheimer's disease is the most common neurodegenerative disease, and many patients also present with vascular dysfunction. In this study, we aimed to assess cerebral blood flow (CBF) and cerebrovascular response (CVR) as early, pre-symptomatic (3 months of age), imaging markers in a bigenic model of Alzheimer's disease (APP.V717IxTau.P301L, biAT) and in the monogenic parental strains. We further developed our previously published combination of pulsed arterial spin labeling perfusion MRI and hypo-ventilation paradigm, which allows weaning of the mice from the ventilator. Furthermore, the commonly used isoflurane anesthesia induces vasodilation and is thereby inherently a vascular challenge. We therefore assessed perfusion differences in the mouse models under free-breathing isoflurane conditions. We report (i) that we can determine CBF and hypoventilation-based CVR under ketamine/midazolam anesthesia and wean mice from the ventilator, making it a valuable tool for assessment of CBF and CVR in mice, (ii) that biAT mice exhibit lower cortical CBF than wild-type mice at age 3 months, (iii) that CVR was increased in both biAT and APP.V717I mice but not in Tau.P301L mice, identifying the APP genotype as a strong influencer of brain CVR and (iv) that perfusion differences at baseline are masked by the widely used isoflurane anesthesia.
Collapse
Affiliation(s)
- Kristof Govaerts
- Biomedical MRI/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Benoit Lechat
- LEGTEGG, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Tom Struys
- Morphology Research Group, Biomedical Research Institute, Universiteit Hasselt, Hasselt, Belgium
| | - Anna Kremer
- LEGTEGG, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Peter Borghgraef
- LEGTEGG, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Fred Van Leuven
- LEGTEGG, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Uwe Himmelreich
- Biomedical MRI/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Tom Dresselaers
- Biomedical MRI/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| |
Collapse
|
4
|
Mouse models of neurodegenerative disease: preclinical imaging and neurovascular component. Brain Imaging Behav 2017; 12:1160-1196. [PMID: 29075922 DOI: 10.1007/s11682-017-9770-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Neurodegenerative diseases represent great challenges for basic science and clinical medicine because of their prevalence, pathologies, lack of mechanism-based treatments, and impacts on individuals. Translational research might contribute to the study of neurodegenerative diseases. The mouse has become a key model for studying disease mechanisms that might recapitulate in part some aspects of the corresponding human diseases. Neurodegenerative disorders are very complicated and multifactorial. This has to be taken in account when testing drugs. Most of the drugs screening in mice are very difficult to be interpretated and often useless. Mouse models could be condiderated a 'pathway models', rather than as models for the whole complicated construct that makes a human disease. Non-invasive in vivo imaging in mice has gained increasing interest in preclinical research in the last years thanks to the availability of high-resolution single-photon emission computed tomography (SPECT), positron emission tomography (PET), high field Magnetic resonance, Optical Imaging scanners and of highly specific contrast agents. Behavioral test are useful tool to characterize different animal models of neurodegenerative pathology. Furthermore, many authors have observed vascular pathological features associated to the different neurodegenerative disorders. Aim of this review is to focus on the different existing animal models of neurodegenerative disorders, describe behavioral tests and preclinical imaging techniques used for diagnose and describe the vascular pathological features associated to these diseases.
Collapse
|
5
|
Klohs J, Rudin M, Shimshek DR, Beckmann N. Imaging of cerebrovascular pathology in animal models of Alzheimer's disease. Front Aging Neurosci 2014; 6:32. [PMID: 24659966 PMCID: PMC3952109 DOI: 10.3389/fnagi.2014.00032] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/19/2014] [Indexed: 01/04/2023] Open
Abstract
In Alzheimer's disease (AD), vascular pathology may interact with neurodegeneration and thus aggravate cognitive decline. As the relationship between these two processes is poorly understood, research has been increasingly focused on understanding the link between cerebrovascular alterations and AD. This has at last been spurred by the engineering of transgenic animals, which display pathological features of AD and develop cerebral amyloid angiopathy to various degrees. Transgenic models are versatile for investigating the role of amyloid deposition and vascular dysfunction, and for evaluating novel therapeutic concepts. In addition, research has benefited from the development of novel imaging techniques, which are capable of characterizing vascular pathology in vivo. They provide vascular structural read-outs and have the ability to assess the functional consequences of vascular dysfunction as well as to visualize and monitor the molecular processes underlying these pathological alterations. This article focusses on recent in vivo small animal imaging studies addressing vascular aspects related to AD. With the technical advances of imaging modalities such as magnetic resonance, nuclear and microscopic imaging, molecular, functional and structural information related to vascular pathology can now be visualized in vivo in small rodents. Imaging vascular and parenchymal amyloid-β (Aβ) deposition as well as Aβ transport pathways have been shown to be useful to characterize their dynamics and to elucidate their role in the development of cerebral amyloid angiopathy and AD. Structural and functional imaging read-outs have been employed to describe the deleterious affects of Aβ on vessel morphology, hemodynamics and vascular integrity. More recent imaging studies have also addressed how inflammatory processes partake in the pathogenesis of the disease. Moreover, imaging can be pivotal in the search for novel therapies targeting the vasculature.
Collapse
Affiliation(s)
- Jan Klohs
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich Zurich, Switzerland ; Neuroscience Center Zurich, University of Zurich and ETH Zurich Zurich, Switzerland
| | - Markus Rudin
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich Zurich, Switzerland ; Neuroscience Center Zurich, University of Zurich and ETH Zurich Zurich, Switzerland ; Institute of Pharmacology and Toxicology, University of Zurich Zurich, Switzerland
| | - Derya R Shimshek
- Autoimmunity, Transplantation and Inflammation/Neuroinflammation Department, Novartis Institutes for BioMedical Research Basel, Switzerland
| | - Nicolau Beckmann
- Analytical Sciences and Imaging, Novartis Institutes for BioMedical Research Basel, Switzerland
| |
Collapse
|
6
|
Alzheimer's disease biomarkers: correspondence between human studies and animal models. Neurobiol Dis 2013; 56:116-30. [PMID: 23631871 DOI: 10.1016/j.nbd.2013.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 04/11/2013] [Accepted: 04/18/2013] [Indexed: 01/05/2023] Open
Abstract
Alzheimer's disease (AD) represents an escalating global threat as life expectancy and disease prevalence continue to increase. There is a considerable need for earlier diagnoses to improve clinical outcomes. Fluid biomarkers measured from cerebrospinal fluid (CSF) and blood, or imaging biomarkers have considerable potential to assist in the diagnosis and management of AD. An additional important utility of biomarkers is in novel therapeutic development and clinical trials to assess efficacy and side effects of therapeutic interventions. Because many biomarkers are initially examined in animal models, the extent to which markers translate from animals to humans is an important issue. The current review highlights many existing and pipeline biomarker approaches, focusing on the degree of correspondence between AD patients and animal models. The review also highlights the need for greater translational correspondence between human and animal biomarkers.
Collapse
|
7
|
Perles-Barbacaru TA, Procissi D, Demyanenko AV, Jacobs RE. Quantitative pharmacologic MRI in mice. NMR IN BIOMEDICINE 2012; 25:498-505. [PMID: 21793079 PMCID: PMC3292675 DOI: 10.1002/nbm.1760] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 05/03/2011] [Accepted: 05/19/2011] [Indexed: 05/31/2023]
Abstract
Pharmacologic MRI (phMRI) uses functional MRI techniques to provide a noninvasive in vivo measurement of the hemodynamic effects of drugs. The cerebral blood volume change (ΔCBV) serves as a surrogate for neuronal activity via neurovascular coupling mechanisms. By assessing the location and time course of brain activity in mouse mutant studies, phMRI can provide valuable insights into how different behavioral phenotypes are expressed in deferring brain activity response to drug challenge. In this report, we evaluate the utility of three different intravascular ultrasmall superparamagnetic iron oxide (USPIO) contrast agents for phMRI using a gradient-echo technique, with temporal resolution of one min at high magnetic field. The tissue half-life of the USPIOs was studied using a nonlinear detrending model. The three USPIOs are candidates for CBV weighted phMRI experiments, with r(2)/r(1) ratios ≥ 20 and apparent half-lives ≥ 1.5 h at the described doses. An echo-time of about 10 ms or longer results in a functional contrast to noise ratio (fCNR) > 75 after USPIO injection, with negligible decrease between 1.5-2 h. phMRI experiments were conducted at 7 T using cocaine as a psychotropic substance and acetazolamide, a global vasodilator, as a positive control. Cocaine acts as a dopamine-serotonin-norepinephrine reuptake inhibitor, increasing extracellular concentrations of these neurotransmitters, and thus increasing dopaminergic, serotonergic and noradrenergic neurotransmission. phMRI results showed that CBV was reduced in the normal mouse brain after cocaine challenge, with the largest effects in the nucleus accumbens, whereas after acetazolamide, blood volume was increased in both cerebral and extracerebral tissue.
Collapse
Affiliation(s)
| | - Daniel Procissi
- Biological Imaging Center, Beckman Institute, California Institute of Technology, Pasadena, CA 91125
| | - Andrey V. Demyanenko
- Biological Imaging Center, Beckman Institute, California Institute of Technology, Pasadena, CA 91125
| | - Russell E. Jacobs
- Biological Imaging Center, Beckman Institute, California Institute of Technology, Pasadena, CA 91125
| |
Collapse
|
8
|
Magnetic resonance imaging and histological evidence for the blockade of cuprizone-induced demyelination in C57BL/6 mice. Neuroscience 2012; 202:446-53. [DOI: 10.1016/j.neuroscience.2011.10.051] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 10/27/2011] [Accepted: 10/27/2011] [Indexed: 11/16/2022]
|
9
|
Mouse phenotyping with MRI. Methods Mol Biol 2011. [PMID: 21874500 DOI: 10.1007/978-1-61779-219-9_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and evaluating mouse models of human disease. Image results can provide important comparisons of human conditions with mouse disease models, evaluations of treatment, development or disease progression, as well as direction for histological or other investigations. Effective mouse MRI studies require attention to many aspects of experiment design. In this chapter, we provide details and discussion of important practical considerations: hardware requirements, mouse handling for in vivo imaging, specimen preparation for ex vivo imaging, sequence and contrast agent selection, study size, and quantitative image analysis. We focus particularly on anatomical phenotyping, an important and accessible application that has shown a high potential for impact in many mouse models at our imaging center.
Collapse
|
10
|
Lambert JC, Dallongeville J, Ellis KA, Schraen-Maschke S, Lui J, Laws S, Dumont J, Richard F, Cottel D, Berr C, Ames D, Masters CL, Rowe CC, Szoeke C, Tzourio C, Dartigues JF, Buée L, Martins R, Amouyel P. Association of plasma Aß peptides with blood pressure in the elderly. PLoS One 2011; 6:e18536. [PMID: 21525986 PMCID: PMC3078119 DOI: 10.1371/journal.pone.0018536] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 03/03/2011] [Indexed: 01/10/2023] Open
Abstract
Background Aß peptides are often considered as catabolic by-products of the amyloid ß protein precursor (APP), with unknown physiological functions. However, several biological properties have been tentatively attributed to these peptides, including a role in vasomotion. We assess whether plasma Aß peptide levels might be associated with systolic and diastolic blood pressure values (SBP and DBP, respectively). Methodology/Principal Findings Plasma Aß1-40 and Aß1-42 levels were measured using an xMAP-based assay in 1,972 individuals (none of whom were taking antihypertensive drugs) from 3 independent studies: the French population-based 3C and MONA-LISA (Lille) studies (n = 627 and n = 769, respectively) and the Australian, longitudinal AIBL study (n = 576). In the combined sample, the Aß1-42/ Aß1-40 ratio was significantly and inversely associated with SBP (p = 0.03) and a similar trend was observed for DBP (p = 0.06). Using the median age (69) as a cut-off, the Aß1-42/Aß1-40 ratio was strongly associated with both SBP and DBP in elderly individuals (p = 0.002 and p = 0.03, respectively). Consistently, a high Aß1-42/ Aß1-40 ratio was associated with a lower risk of hypertension in both the combined whole sample (odds ratio [OR], 0.71; 95% confidence interval [CI], 0.56-0.90) and (to an even greater extent) in the elderly subjects (OR, 0.53; 95% CI, 0.37–0.75). Lastly, all these associations appeared to be primarily driven by the level of plasma Aß1-40. Conclusion The plasma Aß1-42/Aß1-40 ratio is inversely associated with SBP, DBP and the risk of hypertension in elderly subjects, suggesting that Aß peptides affect blood pressure in vivo. These results may be particularly relevant in Alzheimer's disease, in which a high Aß1-42/Aß1-40 plasma ratio is reportedly associated with a decreased risk of incident disease.
Collapse
|
11
|
Sakoğlu U, Upadhyay J, Chin CL, Chandran P, Baker SJ, Cole TB, Fox GB, Day M, Luo F. Paradigm shift in translational neuroimaging of CNS disorders. Biochem Pharmacol 2011; 81:1374-87. [PMID: 21219879 DOI: 10.1016/j.bcp.2010.12.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 12/29/2010] [Accepted: 12/29/2010] [Indexed: 12/29/2022]
Abstract
During the last two decades, functional neuroimaging technology, especially functional magnetic resonance imaging (fMRI), has improved tremendously, with new attention towards resting-state functional connectivity of the brain. This development has allowed scientists to study changes in brain structure and function, and probe these two properties under conditions of evoked stimulation, disease and drug administration. In the domain of functional imaging, the identification and characterization of central nervous system (CNS) functional networks have emerged as potential biomarkers for CNS disorders in humans. Recent attempts to translate clinical neuroimaging methodology to preclinical studies have also been carried out, which offer new opportunities in translational neuroscience research. In this paper, we review recent developments in structural and functional MRI and their use to probe functional connectivity in various CNS disorders such as schizophrenia, mood disorders, Alzheimer's disease (AD) and pain.
Collapse
Affiliation(s)
- Unal Sakoğlu
- Translational Imaging/Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Palmer J, Love S. Endothelin receptor antagonists: potential in Alzheimer's disease. Pharmacol Res 2010; 63:525-31. [PMID: 21193044 DOI: 10.1016/j.phrs.2010.12.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 12/17/2010] [Accepted: 12/17/2010] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease (AD) is believed to be initiated by the accumulation of neurotoxic forms of Aβ peptide within the brain. AD patients show reduction of cerebral blood flow (CBF), the extent of the reduction correlating with the impairment of cognition. There is evidence that cerebral hypoperfusion precedes and may even trigger the onset of dementia in AD. Cerebral hypoperfusion impairs neuronal function, reduces the clearance of Aβ peptide and other toxic metabolites from the brain, and upregulates Aβ production. Studies in animal models of AD have shown the reduction in CBF to be more than would be expected for the reduction in neuronal metabolic activity. Aβ may contribute to the reduction in CBF in AD, as both Aβ₁₋₄₀ and Aβ₁₋₄₂ induce cerebrovascular dysfunction. Aβ₁₋₄₀ acts directly on cerebral arteries to cause cerebral smooth muscle cell contraction. Aβ₁₋₄₂ causes increased neuronal production and release of endothelin-1 (ET-1), a potent vasoconstrictor, and upregulation of endothelin-converting enzyme-2 (ECE-2), the enzyme which cleaves ET-1 from its inactive precursor. ET-1 and ECE-2 are also elevated in AD, making it likely that upregulation of the ECE-2-ET-1 axis by Aβ₁₋₄₂ contributes to the chronic reduction of CBF in AD. At present, only a few symptomatic treatment options exist for AD. The involvement of ET-1 in the pathogenesis of endothelial dysfunction associated with elevated Aβ indicates the potential for endothelin receptor antagonists in the treatment of AD. It has already been demonstrated that the endothelin receptor antagonist bosentan, preserves aortic and carotid endothelial function in Tg2576 mice, and our findings suggest that endothelin receptor antagonists may be beneficial in maintaining CBF in AD.
Collapse
Affiliation(s)
- Jennifer Palmer
- Dementia Research Group, Institute of Clinical Neurosciences, School of Clinical Sciences, University of Bristol, Frenchay Hospital, Bristol BS16 1LE, United Kingdom.
| | | |
Collapse
|
13
|
Perles-Barbacaru TA, Procissi D, Demyanenko AV, Hall FS, Uhl GR, Jacobs RE. Quantitative pharmacologic MRI: mapping the cerebral blood volume response to cocaine in dopamine transporter knockout mice. Neuroimage 2010; 55:622-8. [PMID: 21185387 DOI: 10.1016/j.neuroimage.2010.12.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 12/15/2010] [Accepted: 12/17/2010] [Indexed: 12/31/2022] Open
Abstract
The use of pharmacologic MRI (phMRI) in mouse models of brain disorders allows noninvasive in vivo assessment of drug-modulated local cerebral blood volume changes (ΔCBV) as one correlate of neuronal and neurovascular activities. In this report, we employed CBV-weighted phMRI to compare cocaine-modulated neuronal activity in dopamine transporter (DAT) knockout (KO) and wild-type mice. Cocaine acts to block the dopamine, norepinephrine, and serotonin transporters (DAT, NET, and SERT) that clear their respective neurotransmitters from the synapses, helping to terminate cognate neurotransmission. Cocaine consistently reduced CBV, with a similar pattern of regional ΔCBV in brain structures involved in mediating reward in both DAT genotypes. The largest effects (-20% to -30% ΔCBV) were seen in the nucleus accumbens and several cortical regions. Decreasing response amplitudes to cocaine were noted in more posterior components of the cortico-mesolimbic circuit. DAT KO mice had significantly attenuated ΔCBV amplitudes, shortened times to peak response, and reduced response duration in most regions. This study demonstrates that DAT knockout does not abolish the phMRI responses to cocaine, suggesting that adaptations to loss of DAT and/or retained cocaine activity in other monoamine neurotransmitter systems underlie these responses in DAT KO mice.
Collapse
|
14
|
Kagadis GC, Loudos G, Katsanos K, Langer SG, Nikiforidis GC. In vivosmall animal imaging: Current status and future prospects. Med Phys 2010; 37:6421-42. [DOI: 10.1118/1.3515456] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
|
15
|
Characterization of 7- and 19-month-old Tg2576 mice using multimodal in vivo imaging: limitations as a translatable model of Alzheimer's disease. Neurobiol Aging 2010; 33:933-44. [PMID: 20961663 DOI: 10.1016/j.neurobiolaging.2010.08.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 07/07/2010] [Accepted: 08/09/2010] [Indexed: 11/21/2022]
Abstract
With 90% of neuroscience clinical trials failing to see efficacy, there is a clear need for the development of disease biomarkers that can improve the ability to predict human Alzheimer's disease (AD) trial outcomes from animal studies. Several lines of evidence, including genetic susceptibility and disease studies, suggest the utility of fluorodeoxyglucose positron emission tomography (FDG-PET) as a potential biomarker with congruency between humans and animal models. For example, early in AD, patients present with decreased glucose metabolism in the entorhinal cortex and several regions of the brain associated with disease pathology and cognitive decline. While several of the commonly used AD mouse models fail to show all the hallmarks of the disease or the limbic to cortical trajectory, there has not been a systematic evaluation of imaging-derived biomarkers across animal models of AD, contrary to what has been achieved in recent years in the Alzheimer's Disease Neuroimaging Initiative (ADNI) (Miller, 2009). If animal AD models were found to mimic endpoints that correlate with the disease onset, progression, and relapse, then the identification of such markers in animal models could afford the field a translational tool to help bridge the preclinical-clinical gap. Using a combination of FDG-PET and functional magnetic resonance imaging (fMRI), we examined the Tg2576 mouse for global and regional measures of brain glucose metabolism at 7 and 19 months of age. In experiment 1 we observed that at younger ages, when some plaque burden and cognitive deficits have been reported, Tg2576 mice showed hypermetabolism as assessed with FDG-PET. This hypermetabolism decreased with age to levels similar to wild type (WT) counterparts such that the 19-month-old transgenic (Tg) mice did not differ from age matched WTs. In experiment 2, using cerebral blood volume (CBV) fMRI, we demonstrated that the hypermetabolism observed in Tg mice at 7 months could not be explained by changes in hemodynamic parameters as no differences were observed when compared with WTs. Taken together, these data identify brain hypermetabolism in Tg2576 mice which cannot be accounted for by changes in vascular compliance. Instead, the hypermetabolism may reflect a neuronal compensatory mechanism. Our data are discussed in the context of disease biomarker identification and target validation, suggesting little or no utility for translational based studies using Tg2576 mice.
Collapse
|
16
|
Luo F, Rustay NR, Seifert T, Roesner B, Hradil V, Hillen H, Ebert U, Severin JM, Cox BF, Llano DA, Day M, Fox GB. Magnetic resonance imaging detection and time course of cerebral microhemorrhages during passive immunotherapy in living amyloid precursor protein transgenic mice. J Pharmacol Exp Ther 2010; 335:580-8. [PMID: 20823195 DOI: 10.1124/jpet.110.172932] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In recent years immunotherapy-based approaches for treating Alzheimer's disease have become the subject of intensive research. However, an important mechanistic-related safety concern is exacerbation of the risk of microhemorrhage that may be associated with fast removal of amyloid-β (Aβ) deposits found in blood vessels or brain parenchyma. Rapid in vivo detection of microhemorrhages in living amyloid precursor protein transgenic mice has not been described, and histological analysis can take several months before this risk is assessed. Aged transgenic mice were divided into two groups that would undergo longitudinal passive immunotherapy for 12 or 18 weeks. 6G1, a nonselective anti-Aβ monoclonal antibody, and 8F5, a more selective antioligomeric Aβ monoclonal antibody, were examined in both longitudinal studies. High-resolution T2*-weighted magnetic resonance microscopy (100 × 100 × 400 μm) was used for microhemorrhage detection in vivo. Cerebral microhemorrhages by magnetic resonance imaging were compared with histological hemosiderin staining in each animal; results showed that T2*-weighted magnetic resonance microscopy can reliably detect microhemorrhages of ≥60 μm in diameter at baseline and after 12 to 18 weeks of treatment in the same animals in vivo. This correlated significantly with histological readings. This new imaging safety biomarker can be readily applied to preclinical antibody screening in a longitudinal manner. 6G1 and 8F5, however, both increased microhemorrhage incidence in aged amyloid precursor protein transgenic mice compared with their baseline and vehicle treatment. A highly selective antibody for soluble Aβ is needed to address the question of whether antibodies that do not bind to deposited Aβ have microhemorrhage liability.
Collapse
Affiliation(s)
- Feng Luo
- Translational Imaging and Biochemical Biomarkers, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Faure A, Verret L, Bozon B, El Tannir El Tayara N, Ly M, Kober F, Dhenain M, Rampon C, Delatour B. Impaired neurogenesis, neuronal loss, and brain functional deficits in the APPxPS1-Ki mouse model of Alzheimer's disease. Neurobiol Aging 2009; 32:407-18. [PMID: 19398247 DOI: 10.1016/j.neurobiolaging.2009.03.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 03/17/2009] [Accepted: 03/18/2009] [Indexed: 12/18/2022]
Abstract
Amyloid-β peptide species accumulating in the brain of patients with Alzheimer's disease are assumed to have a neurotoxic action and hence to be key actors in the physiopathology of this neurodegenerative disease. We have studied a new mouse mutant (APPxPS1-Ki) line developing both early-onset brain amyloid-β deposition and, in contrast to most of transgenic models, subsequent neuronal loss. In 6-month-old mice, we observed cell layer atrophies in the hippocampus, together with a dramatic decrease in neurogenesis and a reduced brain blood perfusion as measured in vivo by magnetic resonance imaging. In these mice, neurological impairments and spatial hippocampal dependent memory deficits were also substantiated and worsened with aging. We described here a phenotype of APPxPS1-Ki mice that summarizes several neuroanatomical alterations and functional deficits evocative of the human pathology. Such a transgenic model that displays strong face validity might be highly beneficial to future research on AD physiopathogeny and therapeutics.
Collapse
Affiliation(s)
- A Faure
- CNRS, Lab NAMC, UMR8620, Université Paris Sud, 91405, Orsay, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
|