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Steiner P. Brain Fuel Utilization in the Developing Brain. ANNALS OF NUTRITION AND METABOLISM 2020; 75 Suppl 1:8-18. [PMID: 32564020 DOI: 10.1159/000508054] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 03/16/2020] [Indexed: 11/19/2022]
Abstract
During pregnancy and infancy, the human brain is growing extremely fast; the brain volume increases significantly, reaching 36, 72, and 83% of the volume of adults at 2-4 weeks, 1 year, and 2 years of age, respectively, which is essential to establish the neuronal networks and capacity for the development of cognitive, motor, social, and emotional skills that will be continually refined throughout childhood and adulthood. Such dramatic changes in brain structure and function are associated with very large energetic demands exceeding by far those of other organs of the body. It has been estimated that during childhood the brain may account for up to 60% of the body basal energetic requirements. While the main source of energy for the adult brain is glucose, it appears that it is not sufficient to sustain the dramatic metabolic demands of the brain during its development. Recently, it has been proposed that this energetic challenge is solved by the ability of the brain to use ketone bodies (KBs), produced from fatty acid oxidation, as a complement source of energy. Here, we first describe the main cellular and physiological processes that drive brain development along time and how different brain metabolic pathways are engaged to support them. It has been assumed that the majority of energetic substrates are used to support neuronal activity and signal transmission. We discuss how glucose and KBs are metabolized to provide the carbon backbones used to synthesize lipids, nucleic acid, and cholesterol, which are indispensable building blocks of neuronal cell proliferation and are also used to establish and refine brain connectivity through synapse formation/elimination and myelination. We conclude that glucose and KBs are not only important to support the energy needs of the brain under development, but they are also essential substrates for the biosynthesis of macromolecules underlying structural brain growth and reorganization. We emphasize that glucose and fatty acids supporting the production of KBs are provided in complex food matrices, such as breast milk, and understanding how their availability impacts the brain will be key to promote adequate nutrition to support brain metabolism and, therefore, optimal brain development.
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Khayum MA, Moraga-Amaro R, Buwalda B, Koole M, den Boer JA, Dierckx RAJO, Doorduin J, de Vries EFJ. Ovariectomy-induced depressive-like behavior and brain glucose metabolism changes in female rats are not affected by chronic mild stress. Psychoneuroendocrinology 2020; 115:104610. [PMID: 32088632 DOI: 10.1016/j.psyneuen.2020.104610] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 09/23/2019] [Accepted: 01/29/2020] [Indexed: 01/11/2023]
Abstract
The increased incidence of depression in women going through peri-menopause suggests that fluctuations in estrogen levels may increase the risk of developing depression. Nonetheless, this psychiatric disorder is likely to be multifactorial and consequently an additional trigger may be needed to induce depression in this population. Stress could be such a trigger. We therefore investigated the effect of ovarian estrogen depletion and chronic mild stress (CMS) on depressive-like behavior and brain metabolism in female rats. Approximately 2 and 9 weeks after estrogen depletion by ovariectomy, behavioral changes were assessed in the open-field test and the forced swim test, and brain metabolism was measured with [18F]FDG PET imaging. A subset of animals was subjected to a 6-weeks CMS protocol starting 17 days after ovariectomy. Short-term estrogen depletion had a significant effect on brain metabolism in subcortical areas, but not on behavior. Differences in depressive-like behavior were only found after prolonged estrogen depletion, leading to an increased immobility time in the forced swim test. Prolonged estrogen depletion also resulted in an increase in glucose metabolism in frontal cortical areas and hippocampus, whereas a decrease glucose metabolism was found in temporal cortical areas, hypothalamus and brainstem. Neither short-term nor prolonged estrogen depletion caused anxiety-like behavior. Changes in body weight, behavior and brain glucose metabolism were not significantly affected by CMS. In conclusion, ovarian estrogen depletion resulted in changes in brain metabolism and depressive-like behavior, but these changes were not enhanced by CMS.
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Rus T, Tomše P, Jensterle L, Grmek M, Pirtošek Z, Eidelberg D, Tang C, Trošt M. Differential diagnosis of parkinsonian syndromes: a comparison of clinical and automated - metabolic brain patterns' based approach. Eur J Nucl Med Mol Imaging 2020; 47:2901-2910. [PMID: 32337633 DOI: 10.1007/s00259-020-04785-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 03/20/2020] [Indexed: 12/30/2022]
Abstract
PURPOSE Differentiation among parkinsonian syndromes may be clinically challenging, especially at early disease stages. In this study, we used 18F-FDG-PET brain imaging combined with an automated image classification algorithm to classify parkinsonian patients as Parkinson's disease (PD) or as an atypical parkinsonian syndrome (APS) at the time when the clinical diagnosis was still uncertain. In addition to validating the algorithm, we assessed its utility in a "real-life" clinical setting. METHODS One hundred thirty-seven parkinsonian patients with uncertain clinical diagnosis underwent 18F-FDG-PET and were classified using an automated image-based algorithm. For 66 patients in cohort A, the algorithm-based diagnoses were compared with their final clinical diagnoses, which were the gold standard for cohort A and were made 2.2 ± 1.1 years (mean ± SD) later by a movement disorder specialist. Seventy-one patients in cohort B were diagnosed by general neurologists, not strictly following diagnostic criteria, 2.5 ± 1.6 years after imaging. The clinical diagnoses were compared with the algorithm-based ones, which were considered the gold standard for cohort B. RESULTS Image-based automated classification of cohort A resulted in 86.0% sensitivity, 92.3% specificity, 97.4% positive predictive value (PPV), and 66.7% negative predictive value (NPV) for PD, and 84.6% sensitivity, 97.7% specificity, 91.7% PPV, and 95.5% NPV for APS. In cohort B, general neurologists achieved 94.7% sensitivity, 83.3% specificity, 81.8% PPV, and 95.2% NPV for PD, while 88.2%, 76.9%, 71.4%, and 90.9% for APS. CONCLUSION The image-based algorithm had a high specificity and the predictive values in classifying patients before a final clinical diagnosis was reached by a specialist. Our data suggest that it may improve the diagnostic accuracy by 10-15% in PD and 20% in APS when a movement disorder specialist is not easily available.
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Odorcyk FK, Duran-Carabali LE, Rocha DS, Sanches EF, Martini AP, Venturin GT, Greggio S, da Costa JC, Kucharski LC, Zimmer ER, Netto CA. Differential glucose and beta-hydroxybutyrate metabolism confers an intrinsic neuroprotection to the immature brain in a rat model of neonatal hypoxia ischemia. Exp Neurol 2020; 330:113317. [PMID: 32304750 DOI: 10.1016/j.expneurol.2020.113317] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/08/2020] [Accepted: 04/14/2020] [Indexed: 12/12/2022]
Abstract
Neonatal hypoxia ischemia (HI) is the main cause of newborn mortality and morbidity. Preclinical studies have shown that the immature rat brain is more resilient to HI injury, suggesting innate mechanisms of neuroprotection. During neonatal period brain metabolism experience changes that might greatly affect the outcome of HI injury. Therefore, the aim of the present study was to investigate how changes in brain metabolism interfere with HI outcome in different stages of CNS development. For this purpose, animals were divided into 6 groups: HIP3, HIP7 and HIP11 (HI performed at postnatal days 3, 7 and 11, respectively), and their respective shams. In vivo [18F]FDG micro positron emission tomography (microPET) imaging was performed 24 and 72 h after HI, as well as ex-vivo assessments of glucose and beta-hydroxybutyrate (BHB) oxidation. At adulthood behavioral tests and histology were performed. Behavioral and histological analysis showed greater impairments in HIP11 animals, while HIP3 rats were not affected. Changes in [18F]FDG metabolism were found only in the lesion area of HIP11, where a substantial hypometabolism was detected. Furthermore, [18F]FDG hypometabolism predicted impaired cognition and worst histological outcomes at adulthood. Finally, substrate oxidation assessments showed that glucose oxidation remained unaltered and higher level of BHB oxidation found in P3 animals, suggesting a more resilient metabolism. Overall, present results show [18F]FDG microPET predicts long-term injury outcome and suggests that higher BHB utilization is one of the mechanisms that confer the intrinsic neuroprotection to the immature brain and should be explored as a therapeutic target for treatment of HI.
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Lilamand M, Porte B, Cognat E, Hugon J, Mouton-Liger F, Paquet C. Are ketogenic diets promising for Alzheimer's disease? A translational review. ALZHEIMERS RESEARCH & THERAPY 2020; 12:42. [PMID: 32290868 PMCID: PMC7158135 DOI: 10.1186/s13195-020-00615-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 04/02/2020] [Indexed: 01/22/2023]
Abstract
Background Brain amyloid deposition and neurofibrillary tangles in Alzheimer’s disease (AD) are associated with complex neuroinflammatory reactions such as microglial activation and cytokine production. Glucose metabolism is closely related to neuroinflammation. Ketogenic diets (KDs) include a high amount of fat, low carbohydrate and medium-chain triglyceride (MCT) intake. KDs lead to the production of ketone bodies to fuel the brain, in the absence of glucose. These nutritional interventions are validated treatments of pharmacoresistant epilepsy, consequently leading to a better intellectual development in epileptic children. In neurodegenerative diseases and cognitive decline, potential benefits of KD were previously pointed out, but the published evidence remains scarce. The main objective of this review was to critically examine the evidence regarding KD or MCT intake effects both in AD and ageing animal models and in humans. Main body We conducted a review based on a systematic search of interventional trials published from January 2000 to March 2019 found on MEDLINE and Cochrane databases. Overall, 11 animal and 11 human studies were included in the present review. In preclinical studies, this review revealed an improvement of cognition and motor function in AD mouse model and ageing animals. However, the KD and ketone supplementation were also associated with significant weight loss. In human studies, most of the published articles showed a significant improvement of cognitive outcomes (global cognition, memory and executive functions) with ketone supplementation or KD, regardless of the severity of cognitive impairments previously detected. Both interventions seemed acceptable and efficient to achieve ketosis. Conclusion The KD or MCT intake might be promising ways to alter cognitive symptoms in AD, especially at the prodromal stage of the disease. The need for efficient disease-modifying strategies suggests to pursue further KD interventional studies to assess the efficacy, the adherence to this diet and the potential adverse effects of these nutritional approaches.
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Alambyan V, Pace J, Sukpornchairak P, Yu X, Alnimir H, Tatton R, Chitturu G, Yarlagadda A, Ramos-Estebanez C. Imaging Guidance for Therapeutic Delivery: The Dawn of Neuroenergetics. Neurotherapeutics 2020; 17:522-538. [PMID: 32240530 PMCID: PMC7283376 DOI: 10.1007/s13311-020-00843-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Modern neurocritical care relies on ancillary diagnostic testing in the form of multimodal monitoring to address acute changes in the neurological homeostasis. Much of our armamentarium rests upon physiological and biochemical surrogates of organ or regional level metabolic activity, of which a great deal is invested at the metabolic-hemodynamic-hydrodynamic interface to rectify the traditional intermediaries of glucose consumption. Despite best efforts to detect cellular neuroenergetics, current modalities cannot appreciate the intricate coupling between astrocytes and neurons. Invasive monitoring is not without surgical complication, and noninvasive strategies do not provide an adequate spatial or temporal resolution. Without knowledge of the brain's versatile behavior in specific metabolic states (glycolytic vs oxidative), clinical practice would lag behind laboratory empiricism. Noninvasive metabolic imaging represents a new hope in delineating cellular, nigh molecular level energy exchange to guide targeted management in a diverse array of neuropathology.
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Laranjinha J, Nunes C, Ledo A, Lourenço C, Rocha B, Barbosa RM. The Peculiar Facets of Nitric Oxide as a Cellular Messenger: From Disease-Associated Signaling to the Regulation of Brain Bioenergetics and Neurovascular Coupling. Neurochem Res 2020; 46:64-76. [PMID: 32193753 DOI: 10.1007/s11064-020-03015-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 03/07/2020] [Accepted: 03/12/2020] [Indexed: 12/13/2022]
Abstract
In this review, we address the regulatory and toxic role of ·NO along several pathways, from the gut to the brain. Initially, we address the role on ·NO in the regulation of mitochondrial respiration with emphasis on the possible contribution to Parkinson's disease via mechanisms that involve its interaction with a major dopamine metabolite, DOPAC. In parallel with initial discoveries of the inhibition of mitochondrial respiration by ·NO, it became clear the potential for toxic ·NO-mediated mechanisms involving the production of more reactive species and the post-translational modification of mitochondrial proteins. Accordingly, we have proposed a novel mechanism potentially leading to dopaminergic cell death, providing evidence that NO synergistically interact with DOPAC in promoting cell death via mechanisms that involve GSH depletion. The modulatory role of NO will be then briefly discussed as a master regulator on brain energy metabolism. The energy metabolism in the brain is central to the understanding of brain function and disease. The core role of ·NO in the regulation of brain metabolism and vascular responses is further substantiated by discussing its role as a mediator of neurovascular coupling, the increase in local microvessels blood flow in response to spatially restricted increase of neuronal activity. The many facets of NO as intracellular and intercellular messenger, conveying information associated with its spatial and temporal concentration dynamics, involve not only the discussion of its reactions and potential targets on a defined biological environment but also the regulation of its synthesis by the family of nitric oxide synthases. More recently, a novel pathway, out of control of NOS, has been the subject of a great deal of controversy, the nitrate:nitrite:NO pathway, adding new perspectives to ·NO biology. Thus, finally, this novel pathway will be addressed in connection with nitrate consumption in the diet and the beneficial effects of protein nitration by reactive nitrogen species.
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Metastases to the central nervous system: Molecular basis and clinical considerations. J Neurol Sci 2020; 412:116755. [PMID: 32120132 DOI: 10.1016/j.jns.2020.116755] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/17/2020] [Accepted: 02/21/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Metastatic tumors are the most common malignancies of the central nervous system (CNS) in adults. CNS metastases are associated with unfavorable prognosis, high morbidity and mortality. Lung cancer is the most common source of brain metastases, followed by breast cancer and melanoma. Rising incidence is primarily due to improvements in systemic control of primary malignancies, prolonged survival and advances in cancer detection. PURPOSE To provide an overview of the metastatic cascade and the role of angiogenesis, neuroinflammation, metabolic adaptations, and clinical details about brain metastases from different primary tumors. METHODS A review of the literature on brain metastases was conducted, focusing on the pathophysiology and clinical aspects of the disease. PubMed was used to search for relevant articles published from January 1975 through December 2019 using the keywords brain metabolism, brain metastasis, metastatic cascade, molecular mechanisms, incidence, risk factors, and prognosis. 146 articles met the criteria and were included in this review. DISCUSSION Some primary tumors have a higher tendency to metastasize to the CNS. Establishing a suitable metastatic microenvironment is important in maintaining tumor cell growth and survival. Magnetic resonance imaging (MRI) is a widely used tool for diagnosis and treatment monitoring. Available treatments include surgery, radiotherapy, stereotactic radiosurgery, chemotherapy, immunotherapy, and systemic targeted therapies. CONCLUSIONS Prevention of metastases to the CNS remains a difficult challenge. Advances in screening of high-risk patients and future development of novel treatments may improve patient outcomes.
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The Acute and Early Effects of Whole-Brain Irradiation on Glial Activation, Brain Metabolism, and Behavior: a Positron Emission Tomography Study. Mol Imaging Biol 2020; 22:1012-1020. [PMID: 32052277 PMCID: PMC7343765 DOI: 10.1007/s11307-020-01483-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Purpose Radiotherapy is a frequently applied treatment modality for brain tumors. Concomitant irradiation of normal brain tissue can induce various physiological responses. The aim of this study was to investigate whether acute and early-delayed effects of brain irradiation on glial activation and brain metabolism can be detected with positron emission tomography (PET) and whether these effects are correlated with behavioral changes. Procedures Rats underwent 0-, 10-, or 25-Gy whole-brain irradiation. At 3 and 31 days post irradiation, 1-(2-chlorophenyl)-N-[11C]methyl-(1-methylpropyl)-3-isoquinoline carboxamide ([11C]PK11195) and 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) PET scans were acquired to detect changes in glial activation (neuroinflammation) and glucose metabolism, respectively. The open-field test (OFT) was performed on days 6 and 27 to assess behavioral changes. Results Twenty-five-gray-irradiated rats showed higher [11C]PK11195 uptake in most brain regions than controls on day 3 (striatum, hypothalamus, accumbens, septum p < 0.05), although some brain regions had lower uptake (cerebellum, parietal association/retrosplenial visual cortex, frontal association/motor cortex, somatosensory cortex, p < 0.05). On day 31, several brain regions in 25-Gy-irradiated rats still showed significantly higher [11C]PK11195 uptake than controls and 10-Gy-irradiated group (p < 0.05). Within-group analysis showed that [11C]PK11195 uptake in individual brain regions of 25-Gy treated rats remained stable or slightly increased between days 3 and 31. In contrast, a significant reduction (p < 0.05) in tracer uptake between days 3 and 31 was found in all brain areas of controls and 10-Gy-irradiated animals. Moreover, 10-Gy treatment led to a significantly higher [18F]FDG uptake on day 3 (p < 0.05). [18F]FDG uptake decreased between days 3 and 31 in all groups; no significant differences between groups were observed anymore on day 31, except for increased uptake in the hypothalamus in the 10-Gy group. The OFT did not show any significant differences between groups. Conclusions Non-invasive PET imaging indicated that brain irradiation induces neuroinflammation and a metabolic flare, without causing acute or early-delayed behavioral changes. Electronic supplementary material The online version of this article (10.1007/s11307-020-01483-y) contains supplementary material, which is available to authorized users.
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Karaszewski B, Jabłoński B, Żukowicz W. The salvageable brain in acute ischemic stroke. The concept of a reverse mismatch: a mini-review. Metab Brain Dis 2020; 35:237-240. [PMID: 31858389 DOI: 10.1007/s11011-019-00517-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/14/2019] [Indexed: 02/07/2023]
Abstract
Recent studies have opened a new era in treatment of acute ischemic stroke, enabling thrombolysis or thrombectomy far beyond the standard therapeutic "time windows". These therapeutic protocols are built on various combinations of perfusion parameters, lesion volume, and neurological assessment. However, on top of the brain perfusion, there are other multiple factors that might modify the probability of neuronal apoptosis and necrosis following focal cerebral ischemia. We hypothesize that a diagnostic approach with measurements of selected biochemical parameters in the brain, in addition to those based solely on perfusion or MR diffusion, might allow for more personalized management protocols. Moreover, some local processes in the brain, triggered by acute ischemia or its consequences other than hypoperfusion directly, like, for example, excitotoxicity, might lead to apoptosis of the cells in the brain localized also beyond the area of hypoperfusion. This phenomenon might be responsible for the expansion of the brain damage much beyond the initial perfusion deficit or beyond the initial diffusion (DWI) restriction area, reported for example in T2W or FLAIR MRI in some stroke patients who have no other reasons to deteriorate (a reverse DWI - T2W / FLAIR, a reverse perfusion - DWI, or a reverse DWI - DWI mismatch).
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Simon KU, Neto EW, Tramontin NDS, Canteiro PB, Pereira BDC, Zaccaron RP, Silveira PCL, Muller AP. Intranasal insulin treatment modulates the neurotropic, inflammatory, and oxidant mechanisms in the cortex and hippocampus in a low-grade inflammation model. Peptides 2020; 123:170175. [PMID: 31639435 DOI: 10.1016/j.peptides.2019.170175] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 01/05/2023]
Abstract
The inflammatory process plays a critical role in the development of neurodegenerative diseases. Insulin is used in preclinical and clinical studies of neurological disorders. Its intranasal (IN) administration directly in the brain allows for its peripheral metabolic effects to be avoided. Swiss male mice were injected with lipopolysaccharide (LPS) (0.1 mg/kg) to induce low-grade inflammation. IN insulin treatment was initiated 4 h later at a dose of 1.7 IU once daily for 5 days. LPS induced cognitive deficits, which the IN insulin treatment reversed. LPS significantly decreased, whereas IN insulin significantly increased the levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor-β in the cortex. In the hippocampus, IN insulin significantly decreased the BDNF level. LPS significantly increased the interleukin (IL)-6 levels in the cortex, while IN Insulin significantly decreased its levels in the hippocampus. The tumor necrosis factor-α levels were significantly decreased by IN insulin both in the cortex and hippocampus. Moreover, IN insulin significantly increased the IL-10 levels in the cortex. The levels of oxidative and nitrosative stress were significantly higher in the LPS-treated mice; however, IN insulin had a modulatory effect on both. LPS significantly increased the antioxidant enzyme activity both in the cortex and hippocampus, whereas IN insulin significantly increased the activity of both superoxide dismutase and catalase in the hippocampus and that of catalase in the cortex. The hydrogen peroxide levels revealed that LPS significantly affected the electron transport chain. Therefore, IN insulin could be useful in the treatment of neuroinflammatory diseases.
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Brain metabolic signatures across the Alzheimer's disease spectrum. Eur J Nucl Med Mol Imaging 2019; 47:256-269. [PMID: 31811345 DOI: 10.1007/s00259-019-04559-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 09/26/2019] [Indexed: 12/15/2022]
Abstract
PURPOSE Given the challenges posed by the clinical diagnosis of atypical Alzheimer's disease (AD) variants and the limited imaging evidence available in the prodromal phases of atypical AD, we assessed brain hypometabolism patterns at the single-subject level in the AD variants spectrum. Specifically, we tested the accuracy of [18F]FDG-PET brain hypometabolism, as a biomarker of neurodegeneration, in supporting the differential diagnosis of atypical AD variants in individuals with dementia and mild cognitive impairment (MCI). METHODS We retrospectively collected N = 67 patients with a diagnosis of typical AD and AD variants according to the IWG-2 criteria (22 typical-AD, 15 frontal variant-AD, 14 logopenic variant-AD and 16 posterior variant-AD). Further, we included N = 11 MCI subjects, who subsequently received a clinical diagnosis of atypical AD dementia at follow-up (21 ± 11 months). We assessed brain hypometabolism patterns at group- and single-subject level, using W-score maps, measuring their accuracy in supporting differential diagnosis. In addition, the regional prevalence of cerebral hypometabolism was computed to identify the most vulnerable core regions. RESULTS W-score maps pointed at distinct, specific patterns of hypometabolism in typical and atypical AD variants, confirmed by the assessment of core hypometabolism regions, showing that each variant was characterized by specific regional vulnerabilities, namely in occipital, left-sided, or frontal brain regions. ROC curves allowed discrimination among AD variants and also non-AD dementia (i.e., dementia with Lewy bodies and behavioral variant of frontotemporal dementia), with high sensitivity and specificity. Notably, we provide preliminary evidence that, even in AD prodromal phases, these specific [18F]FDG-PET patterns are already detectable and predictive of clinical progression to atypical AD variants at follow-up. CONCLUSIONS The AD variant-specific patterns of brain hypometabolism, highly consistent at single-subject level and already evident in the prodromal stages, represent relevant markers of disease neurodegeneration, with highly supportive diagnostic and prognostic role.
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Kiyatkin EA. Brain temperature and its role in physiology and pathophysiology: Lessons from 20 years of thermorecording. Temperature (Austin) 2019; 6:271-333. [PMID: 31934603 PMCID: PMC6949027 DOI: 10.1080/23328940.2019.1691896] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/11/2022] Open
Abstract
It is well known that temperature affects the dynamics of all physicochemical processes governing neural activity. It is also known that the brain has high levels of metabolic activity, and all energy used for brain metabolism is finally transformed into heat. However, the issue of brain temperature as a factor reflecting neural activity and affecting various neural functions remains in the shadow and is usually ignored by most physiologists and neuroscientists. Data presented in this review demonstrate that brain temperature is not stable, showing relatively large fluctuations (2-4°C) within the normal physiological and behavioral continuum. I consider the mechanisms underlying these fluctuations and discuss brain thermorecording as an important tool to assess basic changes in neural activity associated with different natural (sexual, drinking, eating) and drug-induced motivated behaviors. I also consider how naturally occurring changes in brain temperature affect neural activity, various homeostatic parameters, and the structural integrity of brain cells as well as the results of neurochemical evaluations conducted in awake animals. While physiological hyperthermia appears to be adaptive, enhancing the efficiency of neural functions, under specific environmental conditions and following exposure to certain psychoactive drugs, brain temperature could exceed its upper limits, resulting in multiple brain abnormalities and life-threatening health complications.
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Chung BT, Chen HY, Gordon J, Mammoli D, Sriram R, Autry AW, Le Page LM, Chaumeil MM, Shin P, Slater J, Tan CT, Suszczynski C, Chang S, Li Y, Bok RA, Ronen SM, Larson PEZ, Kurhanewicz J, Vigneron DB. First hyperpolarized [2- 13C]pyruvate MR studies of human brain metabolism. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 309:106617. [PMID: 31648132 PMCID: PMC6880930 DOI: 10.1016/j.jmr.2019.106617] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/04/2019] [Accepted: 10/06/2019] [Indexed: 05/04/2023]
Abstract
We developed methods for the preparation of hyperpolarized (HP) sterile [2-13C]pyruvate to test its feasibility in first-ever human NMR studies following FDA-IND & IRB approval. Spectral results using this MR stable-isotope imaging approach demonstrated the feasibility of investigating human cerebral energy metabolism by measuring the dynamic conversion of HP [2-13C]pyruvate to [2-13C]lactate and [5-13C]glutamate in the brain of four healthy volunteers. Metabolite kinetics, signal-to-noise (SNR) and area-under-curve (AUC) ratios, and calculated [2-13C]pyruvate to [2-13C]lactate conversion rates (kPL) were measured and showed similar but not identical inter-subject values. The kPL measurements were equivalent with prior human HP [1-13C]pyruvate measurements.
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Yoon SY, Lee SC, An YS, Kim YW. Neural correlates and gait characteristics for hypoxic-ischemic brain injury induced freezing of gait. Clin Neurophysiol 2019; 131:46-53. [PMID: 31751839 DOI: 10.1016/j.clinph.2019.09.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 09/04/2019] [Accepted: 09/29/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To investigate gait characteristics in patients with freezing of gait (FOG) after hypoxic-ischemic brain injury (HIBI) and to elucidate neural correlates for FOG using F-18 fluoro-2-deoxy-d-glucose positron emission tomography. METHODS We enrolled 12 patients with FOG after HIBI and 17 patients without FOG after HIBI. We performed three-dimensional gait analyses and compared each parameter and gait variability. Brain metabolism was measured, and we compared regional brain metabolism using a voxel-by-voxel-based statistical mapping analysis. RESULTS The FOG group revealed a significantly decreased joint range of motion (ROM), particularly in the sagittal plane for three-joint summated ROM (p < 0.0025). Spatiotemporal results demonstrated that stride length and step length were decreased in the with FOG group (p < 0.005). FOG severity was negatively correlated with brain metabolism in the left thalamus, and three-joint summated ROM in the sagittal plane was positively associated with brain metabolism in the left thalamus and midbrain (p < 0.05). CONCLUSIONS Central organizational level amplitude disorder may play an important role in the pathophysiology, and disturbance in the cholinergic pathway might contribute to the development of FOG in patients with HIBI. SIGNIFICANCE These findings contribute to understanding FOG in HIBI.
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Beheshti I, Nugent S, Potvin O, Duchesne S. Bias-adjustment in neuroimaging-based brain age frameworks: A robust scheme. Neuroimage Clin 2019; 24:102063. [PMID: 31795063 PMCID: PMC6861562 DOI: 10.1016/j.nicl.2019.102063] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/25/2019] [Accepted: 11/03/2019] [Indexed: 12/21/2022]
Abstract
The level of prediction error in the brain age estimation frameworks is associated with the authenticity of statistical inference on the basis of regression models. In this paper, we present an efficacious and plain bias-adjustment scheme using chronological age as a covariate through the training set for downgrading the prediction bias in a Brain-age estimation framework. We applied proposed bias-adjustment scheme coupled by a machine learning-based brain age framework on a large set of metabolic brain features acquired from 675 cognitively unimpaired adults through fluorodeoxyglucose positron emission tomography data as the training set to build a robust Brain-age estimation framework. Then, we tested the reliability of proposed bias-adjustment scheme on 75 cognitively unimpaired adults, 561 mild cognitive impairment patients as well as 362 Alzheimer's disease patients as independent test sets. Using the proposed method, we gained a strong R2 of 0.81 between the chronological age and brain estimated age, as well as an excellent mean absolute error of 2.66 years on 75 cognitively unimpaired adults as an independent set; whereas an R2 of 0.24 and a mean absolute error of 4.71 years was achieved without bias-adjustment. The simulation results demonstrated that the proposed bias-adjustment scheme has a strong capability to diminish prediction error in brain age estimation frameworks for clinical settings.
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Choi YS, Song JE, Lee JE, Kim E, Kim CH, Kim DH, Song HT. Hyperpolarized [1-13C]lactate flux increased in the hippocampal region in diabetic mice. Mol Brain 2019; 12:88. [PMID: 31675964 PMCID: PMC6824044 DOI: 10.1186/s13041-019-0505-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/01/2019] [Indexed: 01/01/2023] Open
Abstract
Increasing evidence suggests there is a relationship between cognitive impairment and metabolic dysfunction. Diabetes is a chronic disease, and metabolic factors affecting brain metabolisms, such as serum glucose, insulin, and glucagon, are altered according to disease progression. In our previous study, we applied hyperpolarized [1-13C] pyruvate magnetic resonance spectroscopy in prediabetic mice after feeding them a 60% high-fat diet (HFD) for 6 months. Ultimately, we detected significantly increased [1-13C]lactate conversion in the whole brain and an almost five-fold increased [1-13C]lactate/pyruvate ratio in the hippocampal region. In the present study, we induced diabetes in mice by injecting streptozotocin and feeding them an HFD for 6 months. Unlike in prediabetic mice, [1-13C]lactate conversion in the diabetic mice did not differ from that in the control group, but [1-13C]lactate/total 13C ratio showed an almost 1.4-fold increase in the hippocampal region. We measured the amount of the lactate and mRNA levels of glucose transporters from isolated hippocampus and cortex samples. In the hippocampus, significantly decreased GLUT1 mRNA levels and increased lactate were detected, suggesting an inconsistency between glucose and pyruvate metabolism. Pyruvate can be produced from oxaloacetate as well as glucose. We investigated ATP citrate lyase (ACLY) because it cleaves citrate into oxaloacetate and acetyl CoA. Phosphorylated ACLY (Ser455), the active form, was increased in both hippocampus and cortex samples of mice injected with streptozotocin and fed an HFD. Also, phosphorylated ACLY/total ACLY showed a positive correlation with lactate amount in the hippocampus. Our results suggest that the brain has different responses to diabetic progression, but, in the hippocampus, maintains metabolic alteration toward increasing lactate production from the prediabetic to the diabetic stage. We suggest that ACLY-mediated pyruvate be used to support lactate levels in the hippocampus in cases of limited glucose availability.
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Suzuki Y, Kiyosawa M, Wakakura M, Ishii K. Glucose hypometabolism in the visual cortex proportional to disease severity in patients with essential blepharospasm. NEUROIMAGE-CLINICAL 2019; 24:101995. [PMID: 31487599 PMCID: PMC6728873 DOI: 10.1016/j.nicl.2019.101995] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 07/25/2019] [Accepted: 08/25/2019] [Indexed: 11/30/2022]
Abstract
Essential blepharospasm (EB) causes difficulty in eyelid opening because of involuntary movements of the orbicularis oculi muscle. Patients with EB have functional visual loss due to sustained eyelid closure. We examined cerebral glucose metabolism in 39 patients with EB (12 men and 27 women; mean age, 52.1 years) by using positron emission tomography with 18F-fluorodeoxyglucose. Forty-eight eye open healthy subjects and 48 eye close healthy subjects served as controls. We analyzed and compared the data between the patients and controls by using both statistical parametric mapping (SPM) and regions of interest (ROIs). We defined ROIs on both sides of the posterior striate cortex, anterior striate cortex, extrastriate cortex, and thalamus. In SPM analysis, glucose hypometabolism were observed in both sides of the extrastriate cortex compared to eye open controls but not to eye close controls. We also observed a significant negative correlation between the Jankovic Rating Scale (JRS) sum score and relative glucose metabolism level in the striate cortex of these patients. ROI analysis, a significant correlation was observed between the JRS sum score and glucose metabolism level in the posterior (right: r = −0.53, P = .0005; left: r = −0.65, P = .00001) and anterior (right: r = −0.33, P = .04; left: r = −0.37, P = .02) striate cortices of patients with EB. We surmise that the interruption of visual input cause glucose hypometabolism in the visual cortex of patients with EB. Glucose hypometabolism (GM) in the visual cortex in patients with blepharospasm was observed. GM level in the visual cortex of blepharospasm was same as that of eye close healthy subjects. Negative correlation was observed between severity and GM level in the striate cortex of patients. The results of this study reflect the visual symptoms of patients with blepharospasm.
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Braissant O, Rackayová V, Pierzchala K, Grosse J, McLin VA, Cudalbu C. Longitudinal neurometabolic changes in the hippocampus of a rat model of chronic hepatic encephalopathy. J Hepatol 2019; 71:505-515. [PMID: 31173812 DOI: 10.1016/j.jhep.2019.05.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 05/24/2019] [Accepted: 05/27/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS The sequence of events in hepatic encephalopathy (HE) remains unclear. Using the advantages of in vivo 1H-MRS (9.4T) we aimed to analyse the time-course of disease in an established model of type C HE by analysing the longitudinal changes in a large number of brain metabolites together with biochemical, histological and behavioural assessment. We hypothesized that neurometabolic changes are detectable very early, and that these early changes will offer insight into the primary events underpinning HE. METHODS Wistar rats underwent bile-duct ligation (BDL) and were studied before BDL and at post-operative weeks 2, 4, 6 and 8 (n = 26). In vivo short echo-time 1H-MRS (9.4T) of the hippocampus was performed in a longitudinal manner, as were biochemical (plasma), histological and behavioural tests. RESULTS Plasma ammonium increased early after BDL and remained high during the study. Brain glutamine increased (+47%) as early as 2-4 weeks post-BDL while creatine (-8%) and ascorbate (-12%) decreased. Brain glutamine and ascorbate correlated closely with rising plasma ammonium, while brain creatine correlated with brain glutamine. The increases in brain glutamine and plasma ammonium were correlated, while plasma ammonium correlated negatively with distance moved. Changes in astrocyte morphology were observed at 4 weeks. These early changes were further accentuated at 6-8 weeks post-BDL, concurrently with the known decreases in brain organic osmolytes. CONCLUSION Using a multimodal, in vivo and longitudinal approach we have shown that neurometabolic changes are already noticeable 2 weeks after BDL. These early changes are suggestive of osmotic/oxidative stress and are likely the premise of some later changes. Early decreases in cerebral creatine and ascorbate are novel findings offering new avenues to explore neuroprotective strategies for HE treatment. LAY SUMMARY The sequence of events in chronic hepatic encephalopathy (HE) remains unclear, therefore using the advantages of in vivo proton magnetic resonance spectroscopy at 9.4T we aimed to test the hypothesis that neurometabolic changes are detectable very early in an established model of type C HE, offering insight into the primary events underpinning HE, before advanced liver disease confounds the findings. These early, previously unreported neurometabolic changes occurred as early as 2 to 4 weeks after bile-duct ligation, namely an increase in plasma ammonium and brain glutamine, a decrease in brain creatine and ascorbate together with behavioural and astrocyte morphology changes, and continued to progress throughout the 8-week course of the disease.
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Rousseau PF, Malbos E, Verger A, Nicolas F, Lançon C, Khalfa S, Guedj E. Increase of precuneus metabolism correlates with reduction of PTSD symptoms after EMDR therapy in military veterans: an 18F-FDG PET study during virtual reality exposure to war. Eur J Nucl Med Mol Imaging 2019; 46:1817-1821. [PMID: 31152209 DOI: 10.1007/s00259-019-04360-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/13/2019] [Indexed: 12/29/2022]
Abstract
PURPOSE The prevalence of posttraumatic stress disorder (PTSD) is higher among veterans, and can lead to disastrous consequences such as suicide. Eye movement desensitization and reprocessing (EMDR) is recommended in first-line psychotherapies for PTSD. Virtual reality exposure (VRE) coupled with 18F-FDG PET imaging can highlight the activated brain regions during stress exposure. The objective of this study is to identify, after EMDR therapy, the regions of brain metabolism that evolve during the stress exposure of a war scene with symptomatic remission in a group of military veterans suffering from PTSD, and to secondarily search for predictive metabolic features. METHODS We recruited 15 military veterans suffering from PTSD who performed an 18F-FDG PET sensitized by the exposure to a virtual war scene, before (T0) and after (T1) EMDR therapy. Statistical parametric mapping was used to compare brain metabolism before and after treatment and to study correlations between metabolism and evolution scores on PTSD clinical scales (PTSD Checklist Scale, PCLS; Clinician-Administered PTSD Scale, CAPS). RESULTS The metabolic activity of the precuneus was increased after EMDR therapy (p < 0.005 uncorrected, k > 180) and correlated with clinical improvement with the CAPS scale (r = -0.73 and p < 0.001). Moreover, the precuneus metabolic value before therapy predicted the clinical improvement on the PCLS scale (T1-T0) after EMDR (r = -0.667 and p < 0.006). CONCLUSION The clinical improvement in military patients with PTSD after EMDR is related to increased precuneus metabolism upon VR stress exposure.
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Insulin treatment protects the brain against neuroinflammation by reducing cerebral cytokines and modulating mitochondrial function. Brain Res Bull 2019; 149:120-128. [PMID: 31002914 DOI: 10.1016/j.brainresbull.2019.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/12/2019] [Accepted: 04/14/2019] [Indexed: 12/22/2022]
Abstract
In the central nervous system, glial cells protect the brain against neuronal stress by inducing inflammatory responses; namely, intracellular signaling and cytokine production. However, chronic inflammation is often associated with degenerative diseases that can damage hormone signaling and mitochondrial function. Lipopolysaccharide (LPS) induces neuroinflammation by stimulating the production of interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α); moreover, it generates oxidative stress and impairs cognitive functions. The aim of the present study was to assess the therapeutic efficacy of intracerebroventricular (i.c.v.) injections of insulin against neuroinflammation. Inflammation was first induced in male Wistar rats (60 days old, n = 12/group) through an intraperitoneal injection of 0.1 mg/kg LPS. The i.c.v. insulin treatment at a 0.5 mU dose was initiated 4 h later and administered once a day for 5 days. Thereafter, the spatial memory of the rats was assessed, and the hippocampus and cortex were later dissected for biochemical analyses. Our results showed that LPS induced cognitive function impairments, but the insulin treatment reversed these effects. Whereas the levels of brain-derived neurotrophic factor and beta-nerve growth factor in the hippocampus were not altered by LPS, they were decreased in the cortex by insulin. The IL-1β and TNF-α levels were increased in the cortex and hippocampus following exposure to LPS, but insulin reversed these effects. Evaluation of the H2O2levels and mitochondrial membrane potential revealed that LPS modulated mitochondrial function, an effect that was also reversed by insulin. Moreover, LPS induced oxidative stress by decreasing the superoxide dismutase and catalase activities and glutathione and sulfhydryl levels. Furthermore, the levels of oxidative stress probes/markers (i.e.,2',7'-dichlorodihydrofluoresceindiacetateand nitrite) were higher in the LPS-treated rats. These effects were all reversed in the cortex and hippocampus by insulin treatment. Our results suggest a potential role for insulin as a therapeutic drug against inflammatory diseases associated with mitochondrial dysfunction in the brain.
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Metabolic perturbations after pediatric TBI: It's not just about glucose. Exp Neurol 2019; 316:74-84. [PMID: 30951705 DOI: 10.1016/j.expneurol.2019.03.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/13/2019] [Accepted: 03/30/2019] [Indexed: 12/22/2022]
Abstract
Improved patient survival following pediatric traumatic brain injury (TBI) has uncovered a currently limited understanding of both the adaptive and maladaptive metabolic perturbations that occur during the acute and long-term phases of recovery. While much is known about the redundancy of metabolic pathways that provide adequate energy and substrates for normal brain growth and development, the field is only beginning to characterize perturbations in these metabolic pathways after pediatric TBI. To date, the majority of studies have focused on dysregulated oxidative glucose metabolism after injury; however, the immature brain is well-equipped to use alternative substrates to fuel energy production, growth, and development. A comprehensive understanding of metabolic changes associated with pediatric TBI cannot be limited to investigations of glucose metabolism alone. All energy substrates used by the brain should be considered in developing nutritional and pharmacological interventions for pediatric head trauma. This review summarizes post-injury changes in brain metabolism of glucose, lipids, ketone bodies, and amino acids with discussion of the therapeutic potential of altering substrate utilization to improve pediatric TBI outcomes.
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Akaishi T, Onishi E, Abe M, Toyama H, Ishizawa K, Kumagai M, Kubo R, Nakashima I, Aoki M, Yamauchi M, Ishii T. The human central nervous system discharges carbon dioxide and lactic acid into the cerebrospinal fluid. Fluids Barriers CNS 2019; 16:8. [PMID: 30922337 PMCID: PMC6440017 DOI: 10.1186/s12987-019-0128-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 03/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The central nervous system was previously thought to draw oxygen and nutrition from the arteries and discharge carbon dioxide and other metabolic wastes into the venous system. At present, the functional role of cerebrospinal fluid in brain metabolism is not fully known. METHODS In this prospective observational study, we performed gas analysis on venous blood and cerebrospinal fluid simultaneously acquired from 16 consecutive preoperative patients without any known neurological disorders. RESULTS The carbon dioxide partial pressure (pCO2) (p < 0.0001) and lactic acid level (p < 0.001) in the cerebrospinal fluid were significantly higher than those in the peripheral venous blood, suggesting that a considerable proportion of metabolic carbon dioxide and lactic acid is discharged from the central nervous system into the cerebrospinal fluid. The oxygen partial pressure (pO2) was much higher in the cerebrospinal fluid than in the venous blood, corroborating the conventional theory of cerebrospinal fluid circulatory dynamics. The pCO2 of the cerebrospinal fluid showed a strong negative correlation with age (R = - 0.65, p = 0.0065), but the other studied variables did not show significant correlation with age. CONCLUSION Carbon dioxide and lactic acid are discharged into the circulating cerebrospinal fluid, as well as into the venules. The level of carbon dioxide in the cerebrospinal fluid significantly decreased with age.
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Kopschina Feltes P, de Vries EFJ, Juarez-Orozco LE, Kurtys E, Dierckx RAJO, Moriguchi-Jeckel CM, Doorduin J. Repeated social defeat induces transient glial activation and brain hypometabolism: A positron emission tomography imaging study. J Cereb Blood Flow Metab 2019; 39:439-453. [PMID: 29271288 PMCID: PMC6399731 DOI: 10.1177/0271678x17747189] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/25/2017] [Accepted: 11/08/2017] [Indexed: 01/22/2023]
Abstract
Psychosocial stress is a risk factor for the development of depression. Recent evidence suggests that glial activation could contribute to the development of depressive-like behaviour. This study aimed to evaluate in vivo whether repeated social defeat (RSD) induces short- and long-term inflammatory and metabolic alterations in the brain through positron emission tomography (PET). Male Wistar rats ( n = 40) were exposed to RSD by dominant Long-Evans rats on five consecutive days. Behavioural and biochemical alterations were assessed at baseline, day 5/6 and day 24/25 after the RSD protocol. Glial activation (11C-PK11195 PET) and changes in brain metabolism (18F-FDG PET) were evaluated on day 6, 11 and 25 (short-term), and at 3 and 6 months (long-term). Defeated rats showed transient depressive- and anxiety-like behaviour, increased corticosterone and brain IL-1β levels, as well as glial activation and brain hypometabolism in the first month after RSD. During the third- and six-month follow-up, no between-group differences in any investigated parameter were found. Therefore, non-invasive PET imaging demonstrated that RSD induces transient glial activation and reduces brain glucose metabolism in rats. These imaging findings were associated with stress-induced behavioural changes and support the hypothesis that neuroinflammation could be a contributing factor in the development of depression.
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Caminiti SP, Sala A, Iaccarino L, Beretta L, Pilotto A, Gianolli L, Iannaccone S, Magnani G, Padovani A, Ferini-Strambi L, Perani D. Brain glucose metabolism in Lewy body dementia: implications for diagnostic criteria. ALZHEIMERS RESEARCH & THERAPY 2019; 11:20. [PMID: 30797240 PMCID: PMC6387558 DOI: 10.1186/s13195-019-0473-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 02/10/2019] [Indexed: 01/09/2023]
Abstract
BACKGROUND [18F]FDG-PET hypometabolism patterns are indicative of different neurodegenerative conditions, even from the earliest disease phase. This makes [18F]FDG-PET a valuable tool in the diagnostic workup of neurodegenerative diseases. The utility of [18F]FDG-PET in dementia with Lewy bodies (DLB) needs further validation by considering large samples of patients and disease comparisons and applying state-of-the-art statistical methods. Here, we aimed to provide an extensive validation of the [18F]FDG-PET metabolic signatures in supporting DLB diagnosis near the first clinical assessment, which is characterized by high diagnostic uncertainty, at the single-subject level. METHODS In this retrospective study, we included N = 72 patients with heterogeneous clinical classification at entry (mild cognitive impairment, atypical parkinsonisms, possible DLB, probable DLB, and other dementias) and an established diagnosis of DLB at a later follow-up. We generated patterns of [18F]FDG-PET hypometabolism in single cases by using a validated voxel-wise analysis (p < 0.05, FWE-corrected). The hypometabolism patterns were independently classified by expert raters blinded to any clinical information. The final clinical diagnosis at follow-up (2.94 ± 1.39 [0.34-6.04] years) was considered as the diagnostic reference and compared with clinical classification at entry and with [18F]FDG-PET classification alone. In addition, we calculated the diagnostic accuracy of [18F]FDG-PET maps in the differential diagnosis of DLB with Alzheimer's disease dementia (ADD) (N = 60) and Parkinson's disease (PD) (N = 36). RESULTS The single-subject [18F]FDG-PET hypometabolism pattern, showing temporo-parietal and occipital involvement, was highly consistent across DLB cases. Clinical classification at entry produced several misclassifications with an agreement of only 61.1% with the diagnostic reference. On the contrary, [18F]FDG-PET hypometabolism maps alone accurately predicted diagnosis of DLB at follow-up (88.9%). The high power of the [18F]FDG-PET hypometabolism signature in predicting the final clinical diagnosis allowed a ≈ 50% increase in accuracy compared to the first clinical assessment alone. Finally, [18F]FDG-PET hypometabolism maps yielded extremely high discriminative power, distinguishing DLB from ADD and PD conditions with an accuracy of > 90%. CONCLUSION The present validation of the diagnostic and prognostic accuracy of the disease-specific brain metabolic signature in DLB at the single-subject level argues for the consideration of [18F]FDG-PET in the early phase of the DLB diagnostic flowchart. The assessment of the [18F]FDG-PET hypometabolism pattern at entry may shorten the diagnostic time, resulting in benefits for treatment options and management of patients.
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