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Wang J, Huffman D, Ajwad A, McLouth CJ, Bachstetter A, Kohler K, Murphy MP, O'Hara BF, Duncan MJ, Sunderam S. Thermoneutral temperature exposure enhances slow-wave sleep with a correlated improvement in amyloid pathology in a triple-transgenic mouse model of Alzheimer's disease. Sleep 2024; 47:zsae078. [PMID: 38512801 DOI: 10.1093/sleep/zsae078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 01/14/2024] [Indexed: 03/23/2024] Open
Abstract
Accumulation of amyloid-β (Aβ) plays an important role in Alzheimer's disease (AD) pathology. There is growing evidence that disordered sleep may accelerate AD pathology by impeding the physiological clearance of Aβ from the brain that occurs in normal sleep. Therapeutic strategies for improving sleep quality may therefore help slow disease progression. It is well documented that the composition and dynamics of sleep are sensitive to ambient temperature. We therefore compared Aβ pathology and sleep metrics derived from polysomnography in 12-month-old female 3xTg-AD mice (n = 8) exposed to thermoneutral temperatures during the light period over 4 weeks to those of age- and sex-matched controls (n = 8) that remained at normal housing temperature (22°C) during the same period. The treated group experienced greater proportions of slow wave sleep (SWS)-i.e. epochs of elevated 0.5-2 Hz EEG slow wave activity during non-rapid eye movement (NREM) sleep-compared to controls. Assays performed on mouse brain tissue harvested at the end of the experiment showed that exposure to thermoneutral temperatures significantly reduced levels of DEA-soluble (but not RIPA- or formic acid-soluble) Aβ40 and Aβ42 in the hippocampus, though not in the cortex. With both groups pooled together and without regard to treatment condition, NREM sleep continuity and any measure of SWS within NREM at the end of the treatment period were inversely correlated with DEA-soluble Aβ40 and Aβ42 levels, again in the hippocampus but not in the cortex. These findings suggest that experimental manipulation of SWS could offer useful clues into the mechanisms and treatment of AD.
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Affiliation(s)
- Jun Wang
- F. Joseph Halcomb III, MD, Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Dillon Huffman
- F. Joseph Halcomb III, MD, Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Asma'a Ajwad
- F. Joseph Halcomb III, MD, Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
- Department of Physiology, University of Diyala College of Medicine, Diyala, Iraq
| | | | - Adam Bachstetter
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
| | - Katarina Kohler
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - M Paul Murphy
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Bruce F O'Hara
- Department of Biology, University of Kentucky, Lexington, KY, USA
| | - Marilyn J Duncan
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
| | - Sridhar Sunderam
- F. Joseph Halcomb III, MD, Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
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2
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Sinclair D, Canty AJ, Ziebell JM, Woodhouse A, Collins JM, Perry S, Roccati E, Kuruvilla M, Leung J, Atkinson R, Vickers JC, Cook AL, King AE. Experimental laboratory models as tools for understanding modifiable dementia risk. Alzheimers Dement 2024; 20:4260-4289. [PMID: 38687209 PMCID: PMC11180874 DOI: 10.1002/alz.13834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/29/2024] [Accepted: 03/18/2024] [Indexed: 05/02/2024]
Abstract
Experimental laboratory research has an important role to play in dementia prevention. Mechanisms underlying modifiable risk factors for dementia are promising targets for dementia prevention but are difficult to investigate in human populations due to technological constraints and confounds. Therefore, controlled laboratory experiments in models such as transgenic rodents, invertebrates and in vitro cultured cells are increasingly used to investigate dementia risk factors and test strategies which target them to prevent dementia. This review provides an overview of experimental research into 15 established and putative modifiable dementia risk factors: less early-life education, hearing loss, depression, social isolation, life stress, hypertension, obesity, diabetes, physical inactivity, heavy alcohol use, smoking, air pollution, anesthetic exposure, traumatic brain injury, and disordered sleep. It explores how experimental models have been, and can be, used to address questions about modifiable dementia risk and prevention that cannot readily be addressed in human studies. HIGHLIGHTS: Modifiable dementia risk factors are promising targets for dementia prevention. Interrogation of mechanisms underlying dementia risk is difficult in human populations. Studies using diverse experimental models are revealing modifiable dementia risk mechanisms. We review experimental research into 15 modifiable dementia risk factors. Laboratory science can contribute uniquely to dementia prevention.
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Affiliation(s)
- Duncan Sinclair
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Alison J. Canty
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
- Global Brain Health Institute, Trinity CollegeDublinIreland
| | - Jenna M. Ziebell
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Adele Woodhouse
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Jessica M. Collins
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Sharn Perry
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Eddy Roccati
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Maneesh Kuruvilla
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Jacqueline Leung
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Rachel Atkinson
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - James C. Vickers
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Anthony L. Cook
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
| | - Anna E. King
- Wicking Dementia Research and Education Centre, University of TasmaniaHobartTasmaniaAustralia
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Chen B, Schneeberger M. Neuro-Adipokine Crosstalk in Alzheimer's Disease. Int J Mol Sci 2024; 25:5932. [PMID: 38892118 PMCID: PMC11173274 DOI: 10.3390/ijms25115932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 05/24/2024] [Accepted: 05/27/2024] [Indexed: 06/21/2024] Open
Abstract
The connection between body weight alterations and Alzheimer's disease highlights the intricate relationship between the brain and adipose tissue in the context of neurological disorders. During midlife, weight gain increases the risk of cognitive decline and dementia, whereas in late life, weight gain becomes a protective factor. Despite their substantial impact on metabolism, the role of adipokines in the transition from healthy aging to neurological disorders remains largely unexplored. We aim to investigate how the adipose tissue milieu and the secreted adipokines are involved in the transition between biological and pathological aging, highlighting the bidirectional relationship between the brain and systemic metabolism. Understanding the function of these adipokines will allow us to identify biomarkers for early detection of Alzheimer's disease and uncover novel therapeutic options.
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Affiliation(s)
- Bandy Chen
- Laboratory of Neurovascular Control of Homeostasis, Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06510, USA;
| | - Marc Schneeberger
- Laboratory of Neurovascular Control of Homeostasis, Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06510, USA;
- Wu Tsai Institute for Mind and Brain, Yale University, New Haven, CT 06510, USA
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4
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Guo B, Zhang J, Zhang W, Chen F, Liu B. Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review. Crit Rev Food Sci Nutr 2023:1-22. [PMID: 37897083 DOI: 10.1080/10408398.2023.2272769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Neurodegenerative diseases associated with aging are often accompanied by cognitive decline and gut microbiota disorder. But the impact of gut microbiota on these cognitive disturbances remains incompletely understood. Short chain fatty acids (SCFAs) are major metabolites produced by gut microbiota during the digestion of dietary fiber, serving as an energy source for gut epithelial cells and/or circulating to other organs, such as the liver and brain, through the bloodstream. SCFAs have been shown to cross the blood-brain barrier and played crucial roles in brain metabolism, with potential implications in mediating Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanisms that SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, the dietary sources which determine these SCFAs production was not thoroughly evaluated yet. This comprehensive review explores the production of SCFAs by gut microbiota, their transportation through the gut-brain axis, and the potential mechanisms by which they influence age-related neurodegenerative disorders. Also, the review discusses the importance of dietary fiber sources and the challenges associated with harnessing dietary-derived SCFAs as promoters of neurological health in elderly individuals. Overall, this study suggests that gut microbiota-derived SCFAs and/or dietary fibers hold promise as potential targets and strategies for addressing age-related neurodegenerative disorders.
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Affiliation(s)
- Bingbing Guo
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Jingyi Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Weihao Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Feng Chen
- Shenzhen Key Laboratory of Food Nutrition and Health, Institute for Innovative Development of Food Industry, Department of Food Science and Engineering, College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Shenzhen University, Shenzhen, China
| | - Bin Liu
- Shenzhen Key Laboratory of Food Nutrition and Health, Institute for Innovative Development of Food Industry, Department of Food Science and Engineering, College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Shenzhen University, Shenzhen, China
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Association of late-life body mass index with the risk of Alzheimer disease: a 10-year nationwide population-based cohort study. Sci Rep 2022; 12:15298. [PMID: 36097042 PMCID: PMC9468036 DOI: 10.1038/s41598-022-19696-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 09/02/2022] [Indexed: 11/09/2022] Open
Abstract
Existing data for the association between late-life body mass index (BMI) and the risk of Alzheimer’s disease (AD) in the underweight population are limited with conflicting results. A large population-based cohort study of 148,534 individuals aged ≥ 65 years who participated in the national health screening program from 2002 to 2005 was performed using the Korean National Health Insurance Service-Senior cohort database 2006–2015. The risk of AD according to BMI category (kg/m2) in Asians was evaluated using a multivariable Cox regression model, after adjustments for age, sex, lifestyle, low-income status, and comorbidities. To evaluate the association between BMI and AD risk, the underweight population was further subdivided according to the degree of thinness. During the 10-year follow-up period, 22,279 individuals developed AD. Relative to the normal-weight population, the estimated adjusted hazard ratio (HR) for incident AD in the underweight, overweight, and obese populations was 1.17 (95% confidence interval [CI], 1.09–1.24), 0.90 (0.87–0.93), and 0.83 (0.80–0.85), respectively. In the underweight population, AD risk increased as the degree of thinness increased (p for the trend, < .001). Late-life BMI showed a significant inverse relationship with AD risk, especially in the underweight population. Public health strategies to screen for AD more actively in the underweight population and improve their weight status may help reduce the burden of AD.
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6
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Therapeutic potential of Short Chain Fatty acid production by gut microbiota in Neurodegenerative disorders. Nutr Res 2022; 106:72-84. [DOI: 10.1016/j.nutres.2022.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 07/30/2022] [Indexed: 11/20/2022]
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7
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Grasso P. Harnessing the Power of Leptin: The Biochemical Link Connecting Obesity, Diabetes, and Cognitive Decline. Front Aging Neurosci 2022; 14:861350. [PMID: 35527735 PMCID: PMC9072663 DOI: 10.3389/fnagi.2022.861350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/21/2022] [Indexed: 12/02/2022] Open
Abstract
In this review, the current understanding of leptin’s role in energy balance, glycemic regulation, and cognitive function is examined, and its involvement in maintaining the homeostatic “harmony” of these physiologies is explored. The effects of exercise on circulating leptin levels are summarized, and the results of clinical application of leptin to metabolic disease and neurologic dysfunction are reviewed. Finally, pre-clinical evidence is presented which suggests that synthetic peptide leptin mimetics may be useful in resolving not only the leptin resistance associated with common obesity and other elements of metabolic syndrome, but also the peripheral insulin resistance characterizing type 2 diabetes mellitus, and the central insulin resistance associated with certain neurologic deficits in humans.
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Affiliation(s)
- Patricia Grasso
- Department of Medicine, Albany Medical College, Albany, NY, United States
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
- *Correspondence: Patricia Grasso,
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8
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Duncan M, Guerriero L, Kohler K, Beechem L, Gillis B, Salisbury F, Wessel C, Wang J, Sunderam S, Bachstetter A, O’Hara B, Murphy M. Chronic Fragmentation of the Daily Sleep-Wake Rhythm Increases Amyloid-beta Levels and Neuroinflammation in the 3xTg-AD Mouse Model of Alzheimer's Disease. Neuroscience 2022; 481:111-122. [PMID: 34856352 PMCID: PMC8941625 DOI: 10.1016/j.neuroscience.2021.11.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 11/23/2021] [Accepted: 11/25/2021] [Indexed: 01/17/2023]
Abstract
Fragmentation of the daily sleep-wake rhythm with increased nighttime awakenings and more daytime naps is correlated with the risk of development of Alzheimer's disease (AD). To explore whether a causal relationship underlies this correlation, the present study tested the hypothesis that chronic fragmentation of the daily sleep-wake rhythm stimulates brain amyloid-beta (Aβ) levels and neuroinflammation in the 3xTg-AD mouse model of AD. Female 3xTg-AD mice were allowed to sleep undisturbed or were subjected to chronic sleep fragmentation consisting of four daily sessions of enforced wakefulness (one hour each) evenly distributed during the light phase, five days a week for four weeks. Piezoelectric sleep recording revealed that sleep fragmentation altered the daily sleep-wake rhythm to resemble the pattern observed in AD. Levels of amyloid-beta (Aβ40 and Aβ42) determined by ELISA were higher in hippocampal tissue collected from sleep-fragmented mice than from undisturbed controls. In contrast, hippocampal levels of tau and phospho-tau differed minimally between sleep fragmented and undisturbed control mice. Sleep fragmentation also stimulated neuroinflammation as shown by increased expression of markers of microglial activation and proinflammatory cytokines measured by q-RT-PCR analysis of hippocampal samples. No significant effects of sleep fragmentation on Aβ, tau, or neuroinflammation were observed in the cerebral cortex. These studies support the concept that improving sleep consolidation in individuals at risk for AD may be beneficial for slowing the onset or progression of this devastating neurodegenerative disease.
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Affiliation(s)
- M.J. Duncan
- Dept. of Neuroscience, University of Kentucky College of Medicine, Lexington, KY 40536,Co-senior authors, address correspondence to M.J. Duncan at
| | - L.E. Guerriero
- Dept. of Biology, University of Kentucky, Lexington, KY 40506
| | - K. Kohler
- Dept. of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536,Sanders-Brown Center on Aging and Alzheimer’s Disease Center, University of Kentucky College of Medicine, Lexington, KY 40536
| | - L.E. Beechem
- Dept. of Neuroscience, University of Kentucky College of Medicine, Lexington, KY 40536
| | - B.D. Gillis
- Dept. of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536
| | - F. Salisbury
- Dept. of Biology, University of Kentucky, Lexington, KY 40506
| | - C. Wessel
- Sanders-Brown Center on Aging and Alzheimer’s Disease Center, University of Kentucky College of Medicine, Lexington, KY 40536
| | - J. Wang
- Dept. of Biomedical Engineering, University of Kentucky, Lexington, KY 40506
| | - S. Sunderam
- Dept. of Biomedical Engineering, University of Kentucky, Lexington, KY 40506
| | - A.D. Bachstetter
- Dept. of Neuroscience, University of Kentucky College of Medicine, Lexington, KY 40536,Sanders-Brown Center on Aging and Alzheimer’s Disease Center, University of Kentucky College of Medicine, Lexington, KY 40536,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536
| | - B.F. O’Hara
- Dept. of Biology, University of Kentucky, Lexington, KY 40506
| | - M.P. Murphy
- Dept. of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536,Sanders-Brown Center on Aging and Alzheimer’s Disease Center, University of Kentucky College of Medicine, Lexington, KY 40536,Co-senior authors, address correspondence to M.J. Duncan at
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9
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Wu Y, Wang Z, Yin J, Yang B, Fan J, Cheng Z. Association Plasma Aβ42 Levels with Alzheimer's Disease and Its Influencing Factors in Chinese Elderly Population. Neuropsychiatr Dis Treat 2022; 18:1831-1841. [PMID: 36043117 PMCID: PMC9420413 DOI: 10.2147/ndt.s374722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/17/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND AND PURPOSE Intracerebral Aβ protein deposition is an important pathological mechanism of Alzheimer's disease (AD) and is one of the indicators of early diagnosis of AD. However, invasive lumbar puncture and Aβ PET are difficult to perform in primary units, resulting delays in early diagnosis of AD. In recent years, it has been found that plasma Aβ can reflect the pathological state of AD in early stage, but the results are not consistent. The objective of this study was to explore the association between plasma Aβ42 levels and AD cognitive impairment and its influencing factors in Chinese elderly population, so as to provide guidance for the clinical application of plasma Aβ42 as a blood biomarker of AD. METHODS This is a cross-sectional study based on the community population. Plasma samples were collected from 604 healthy controls (HC), 508 mild cognitive impairment (MCI) and 202 dementia with Alzheimer's type (DAT) patients from three cities. We analyzed the correlation between plasma Aβ42 levels and cognitive function and the influence of confounding factors on the relationship between plasma Aβ42 levels and AD. The independent influencing factors of plasma Aβ42 levels were determined by covariance and linear regression analysis. RESULTS Our results suggest that there is a special linear relationship between plasma Aβ42 and cognitive impairment of AD in Chinese elderly population, with Aβ42 levels slightly decreased in early AD and significantly increased in moderate-to-severe AD (P<0.01). There are many factors influencing the association between plasma Aβ42 levels and AD cognitive impairment, and sample source, gender and BMI are independent influencing factors of plasma Aβ42. CONCLUSION This indentifies that plasma Aβ42 may be a peripheral biomarker for AD screening in Chinese elderly population, but it is necessary to establish standardized detection methods and establish different demarcation criteria for various influencing factors.
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Affiliation(s)
- Yue Wu
- Department of Geriatric Psychiatry, The Affiliated Wuxi Mental Health Center of Jiangnan University, Wuxi, People's Republic of China
| | - Zhiqiang Wang
- Department of Clinical Psychology, The Affiliated Wuxi Mental Health Center of Jiangnan University, Wuxi, People's Republic of China
| | - Jiajun Yin
- Brain Science Basic Laboratory, The Affiliated Wuxi Mental Health Center of Jiangnan University, Wuxi, People's Republic of China
| | - Bixiu Yang
- Department of Clinical Psychology, The Affiliated Wuxi Mental Health Center of Jiangnan University, Wuxi, People's Republic of China
| | - Jie Fan
- Department of Geriatric Psychiatry, The Affiliated Wuxi Mental Health Center of Jiangnan University, Wuxi, People's Republic of China
| | - Zaohuo Cheng
- Department of Geriatric Psychiatry, The Affiliated Wuxi Mental Health Center of Jiangnan University, Wuxi, People's Republic of China
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10
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Tian J, Wang T, Jia K, Guo L, Swerdlow RH, Du H. Nonobese Male Patients with Alzheimer's Disease Are Vulnerable to Decrease in Plasma Leptin. J Alzheimers Dis 2022; 88:1017-1027. [PMID: 35723107 PMCID: PMC9553411 DOI: 10.3233/jad-220447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Metabolic dysfunction links to cognitive deficits in Alzheimer's disease (AD). Leptin is an anti-obesity hormone that modulates energy homeostasis and memory function. Although leptin deregulation is implicated in mouse models of AD-like brain pathology, clinical studies have shown inconsistent results regarding an association of leptin with the development of this neurodegenerative disorder. OBJECTIVE We investigated the changes of plasma leptin and the correlation of sex-stratified circulating leptin with cognitive performance, AD-related biological markers, and metabolic status in patients with AD and cognitively unimpaired (CU) counterparts. METHODS We used nonobese AD patients and CU controls in a University of Kansas Medical Center (KUMC) cohort. Plasma leptin levels, circulating AD-related molecules and metabolic profiles were examined and analyzed. RESULTS In contrast to unchanged circulating leptin in females, male patients exhibited decreased plasma leptin levels compared with male CU counterparts. Moreover, plasma leptin showed no correlation with cognitive performance and AD blood biomarkers in patients with either sex. Of note, females but not males demonstrated an association of plasma leptin with body mass index, high density lipoprotein-cholesterol and its ratio with total cholesterol and triglycerides. CONCLUSION Our findings suggest that leptin deficiency is associated with nonobese male AD patients, supporting systemic dysmetabolism in the development of this neurodegenerative disorder in certain populations. Although plasma leptin may have limited capacity to reflect disease severity or progression, future mechanistic studies on the regulation of leptin in nonobese patients with AD would deepen our understanding of the sex-related disparity of AD etiopathogenesis.
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Affiliation(s)
- Jing Tian
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Tienju Wang
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Kun Jia
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Lan Guo
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA
| | - Russell H. Swerdlow
- Department of Neurology, Alzheimer’s Disease Center, University of Kansas Medical Center, Lawrence, KS, USA
| | - Heng Du
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA
- Department of Neurology, Alzheimer’s Disease Center, University of Kansas Medical Center, Lawrence, KS, USA
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11
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Hamilton K, Harvey J. The Neuronal Actions of Leptin and the Implications for Treating Alzheimer's Disease. Pharmaceuticals (Basel) 2021; 14:ph14010052. [PMID: 33440796 PMCID: PMC7827292 DOI: 10.3390/ph14010052] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 12/13/2022] Open
Abstract
It is widely accepted that the endocrine hormone leptin controls food intake and energy homeostasis via activation of leptin receptors expressed on hypothalamic arcuate neurons. The hippocampal formation also displays raised levels of leptin receptor expression and accumulating evidence indicates that leptin has a significant impact on hippocampal synaptic function. Thus, cellular and behavioural studies support a cognitive enhancing role for leptin as excitatory synaptic transmission, synaptic plasticity and glutamate receptor trafficking at hippocampal Schaffer collateral (SC)-CA1 synapses are regulated by leptin, and treatment with leptin enhances performance in hippocampus-dependent memory tasks. Recent studies indicate that hippocampal temporoammonic (TA)-CA1 synapses are also a key target for leptin. The ability of leptin to regulate TA-CA1 synapses has important functional consequences as TA-CA1 synapses are implicated in spatial and episodic memory processes. Moreover, degeneration is initiated in the TA pathway at very early stages of Alzheimer's disease, and recent clinical evidence has revealed links between plasma leptin levels and the incidence of Alzheimer's disease (AD). Additionally, accumulating evidence indicates that leptin has neuroprotective actions in various AD models, whereas dysfunctions in the leptin system accelerate AD pathogenesis. Here, we review the data implicating the leptin system as a potential novel target for AD, and the evidence that boosting the hippocampal actions of leptin may be beneficial.
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12
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Pratap AA, Holsinger RMD. Altered Brain Leptin and Leptin Receptor Expression in the 5XFAD Mouse Model of Alzheimer's Disease. Pharmaceuticals (Basel) 2020; 13:E401. [PMID: 33218163 PMCID: PMC7698839 DOI: 10.3390/ph13110401] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/21/2022] Open
Abstract
Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by the accumulation of amyloid plaques and neurofibrillary tangles. Interestingly, individuals with metabolic syndromes share some pathologies with those diagnosed with AD including neuroinflammation, insulin resistance and cognitive deficits. Leptin, an adipocyte-derived hormone, regulates metabolism, energy expenditure and satiety via its receptor, LepR. To investigate the possible involvement of leptin in AD, we examined the distribution of leptin and LepR in the brains of the 5XFAD mouse model of AD, utilizing immunofluorescent staining in young (10-12-weeks; n = 6) and old (48-52-weeks; n = 6) transgenic (Tg) mice, together with age-matched wild-type (WT) controls for both age groups (young-WT, n = 6; old-WT, n = 6). We also used double immunofluorescent staining to examine the distribution of leptin and leptin receptor expression in astrocytes. In young 5XFAD, young-WT and old-WT mice, we observed neuronal and endothelial expression of leptin and LepR throughout the brain. However, neuronal leptin and LepR expression in the old 5XFAD brain was significantly diminished. Reduced neuronal leptin and LepR expression was accompanied by plaque loading and neuroinflammation in the AD brain. A marked increase in astrocytic leptin and LepR was also observed in old 5XFAD mice compared to younger 5XFAD mice. We postulate that astrocytes may utilize LepR signalling to mediate and drive their metabolically active state when degrading amyloid in the AD brain. Overall, these findings provide evidence of impaired leptin and LepR signalling in the AD brain, supporting clinical and epidemiological studies performed in AD patients.
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Affiliation(s)
- Anishchal A. Pratap
- Brain and Mind Centre, Laboratory of Molecular Neuroscience and Dementia, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2050, Australia;
- Discipline of Pathology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
| | - R. M. Damian Holsinger
- Brain and Mind Centre, Laboratory of Molecular Neuroscience and Dementia, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2050, Australia;
- Discipline of Pathology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
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13
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Bonfili L, Cecarini V, Gogoi O, Gong C, Cuccioloni M, Angeletti M, Rossi G, Eleuteri AM. Microbiota modulation as preventative and therapeutic approach in Alzheimer's disease. FEBS J 2020; 288:2836-2855. [PMID: 32969566 DOI: 10.1111/febs.15571] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/27/2020] [Accepted: 09/17/2020] [Indexed: 12/23/2022]
Abstract
The gut microbiota coevolves with its host, and numerous factors like diet, lifestyle, drug intake and geographical location continuously modify its composition, deeply influencing host health. Recent studies demonstrated that gut dysbiosis can alter normal brain function through the so-called gut-brain axis, a bidirectional communication network between the central nervous system and the gastrointestinal tract, thus playing a key role in the pathogenesis of neurodegenerative disorders, such as Alzheimer's disease (AD). In this perspective, in the constant search for novel treatments in AD, the rational modulation of gut microbiota composition could represent a promising approach to prevent or delay AD onset or to counteract its progression. Preclinical and human studies on microbiota modulation through oral bacteriotherapy and faecal transplantation showed anti-inflammatory and antioxidant effects, upregulation of plasma concentration of neuroprotective hormones, restoration of impaired proteolytic pathways, amelioration of energy homeostasis with consequent decrease of AD molecular hallmarks and improvement of behavioural and cognitive performances. In this review, we dissect the role of gut microbiota in AD and highlight recent advances in the development of new multitarget strategies for microbiota modulation to be used as possible preventative and therapeutic approaches in AD.
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Affiliation(s)
- Laura Bonfili
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Valentina Cecarini
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Olee Gogoi
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Chunmei Gong
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | | | - Mauro Angeletti
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Giacomo Rossi
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - Anna Maria Eleuteri
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy
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Zhang L, Fernandez-Kim SO, Beckett TL, Niedowicz DM, Kohler K, Dasuri K, Bruce-Keller AJ, Murphy MP, Keller JN. The db mutation improves memory in younger mice in a model of Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:2157-2167. [PMID: 31034991 DOI: 10.1016/j.bbadis.2019.04.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 01/09/2023]
Abstract
Alzheimer's disease (AD) is the most common age-related neurodegenerative disease, while obesity is a major global public health problem associated with the metabolic disorder type 2 diabetes mellitus (T2DM). Chronic obesity and T2DM have been identified as invariant risk factors for dementia and late-onset AD, while their impacts on the occurrence and development of AD remain unclear. As shown in our previous study, the diabetic mutation (db, Leprdb/db) induces mixed or vascular dementia in mature to middle-aged APPΔNL/ΔNL x PS1P264L/P264L knock-in mice (db/AD). In the present study, the impacts of the db mutation on young AD mice at 10 weeks of age were evaluated. The db mutation not only conferred young AD mice with severe obesity, impaired glucose regulation and activated mammalian target of rapamycin (mTOR) signaling pathway in the mouse cortex, but lead to a surprising improvement in memory. At this young age, mice also had decreased cerebral Aβ content, which we have not observed at older ages. This was unlikely to be related to altered Aβ synthesis, as both β- and γ-secretase were unchanged. The db mutation also reduced the cortical IL-1β mRNA level and IBA1 protein level in young AD mice, with no significant effect on the activation of microglia and astrocytes. We conclude that the db mutation could transitorily improve the memory of young AD mice, a finding that may be partially explained by the relatively improved glucose homeostasis in the brains of db/AD mice compared to their counterpart AD mice, suggesting that glucose regulation could be a strategy for prevention and treatment of neurodegenerative diseases like AD.
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Affiliation(s)
- Le Zhang
- Institute of Gerontology, Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 JieFang Avenue, Wuhan, Hubei 430030, China; Institute for Dementia Research and Prevention, Pennington Biomedical Research Center/LSU System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
| | - Sun-Ok Fernandez-Kim
- Institute for Dementia Research and Prevention, Pennington Biomedical Research Center/LSU System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
| | - Tina L Beckett
- Sanders Brown Center on Aging, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA; Department of Molecular and Cellular Biochemistry, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA
| | - Dana M Niedowicz
- Sanders Brown Center on Aging, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA; Department of Molecular and Cellular Biochemistry, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA
| | - Katharina Kohler
- Sanders Brown Center on Aging, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA; Department of Molecular and Cellular Biochemistry, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA
| | - Kalavathi Dasuri
- Institute for Dementia Research and Prevention, Pennington Biomedical Research Center/LSU System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
| | - Annadora J Bruce-Keller
- Institute for Dementia Research and Prevention, Pennington Biomedical Research Center/LSU System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
| | - M Paul Murphy
- Sanders Brown Center on Aging, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA; Department of Molecular and Cellular Biochemistry, University of Kentucky, 800 S. Limestone, Sanders Brown 211, Lexington, KY 40536-0230, USA.
| | - Jeffrey N Keller
- Institute for Dementia Research and Prevention, Pennington Biomedical Research Center/LSU System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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15
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Carter CJ. Autism genes and the leukocyte transcriptome in autistic toddlers relate to pathogen interactomes, infection and the immune system. A role for excess neurotrophic sAPPα and reduced antimicrobial Aβ. Neurochem Int 2019; 126:36-58. [PMID: 30862493 DOI: 10.1016/j.neuint.2019.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 02/22/2019] [Accepted: 03/06/2019] [Indexed: 12/20/2022]
Abstract
Prenatal and early childhood infections have been implicated in autism. Many autism susceptibility genes (206 Autworks genes) are localised in the immune system and are related to immune/infection pathways. They are enriched in the host/pathogen interactomes of 18 separate microbes (bacteria/viruses and fungi) and to the genes regulated by bacterial toxins, mycotoxins and Toll-like receptor ligands. This enrichment was also observed for misregulated genes from a microarray study of leukocytes from autistic toddlers. The upregulated genes from this leukocyte study also matched the expression profiles in response to numerous infectious agents from the Broad Institute molecular signatures database. They also matched genes related to sudden infant death syndrome and autism comorbid conditions (autoimmune disease, systemic lupus erythematosus, diabetes, epilepsy and cardiomyopathy) as well as to estrogen and thyrotropin responses and to those upregulated by different types of stressors including oxidative stress, hypoxia, endoplasmic reticulum stress, ultraviolet radiation or 2,4-dinitrofluorobenzene, a hapten used to develop allergic skin reactions in animal models. The oxidative/integrated stress response is also upregulated in the autism brain and may contribute to myelination problems. There was also a marked similarity between the expression signatures of autism and Alzheimer's disease, and 44 shared autism/Alzheimer's disease genes are almost exclusively expressed in the blood-brain barrier. However, in contrast to Alzheimer's disease, levels of the antimicrobial peptide beta-amyloid are decreased and the levels of the neurotrophic/myelinotrophic soluble APP alpha are increased in autism, together with an increased activity of α-secretase. sAPPα induces an increase in glutamatergic and a decrease in GABA-ergic synapses creating and excitatory/inhibitory imbalance that has also been observed in autism. A literature survey showed that multiple autism genes converge on APP processing and that many are able to increase sAPPalpha at the expense of beta-amyloid production. A genetically programmed tilt of this axis towards an overproduction of neurotrophic/gliotrophic sAPPalpha and underproduction of antimicrobial beta-amyloid may explain the brain overgrowth and myelination dysfunction, as well as the involvement of pathogens in autism.
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Affiliation(s)
- C J Carter
- PolygenicPathways, 41C Marina, Saint Leonard's on Sea, TN38 0BU, East Sussex, UK.
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16
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Matos TM, Souza-Talarico JND. How stress mediators can cumulatively contribute to Alzheimer's disease An allostatic load approach. Dement Neuropsychol 2019; 13:11-21. [PMID: 31073376 PMCID: PMC6497016 DOI: 10.1590/1980-57642018dn13-010002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/17/2018] [Indexed: 11/22/2022] Open
Abstract
Allostatic load is defined as the frequent activation of the neuroendocrine, immunological, metabolic and cardiovascular systems, which makes individuals more susceptible to stress-related health problems. According to this model, physiological dysregulations start to emerge decades before diseases manifest. Consequently, stress research has shifted its attention to anticipating the degree of this dysregulation to better understand the impact of stress hormones and other biomarkers on disease progression. In view of the growing number of studies that demonstrate the influence of modifiable risk factors on cognitive decline, in addition to the effects of chronic stress mediators, the objective of the present review was to present an overview of the development of cognitive changes based on studies on stress and its mediators.
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Affiliation(s)
- Tatiane Martins Matos
- Nurse, Master of Science from the School of Nursing, University of
São Paulo (EE-USP), SP, Brazil
| | - Juliana Nery De Souza-Talarico
- Professor at the Department of Medical-Surgical Nursing, School of
Nursing, University of São Paulo (EE-USP), SP, Brazil. PhD In the Area of
Neurobiology of Stress and Cognition
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17
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McGregor G, Harvey J. Regulation of Hippocampal Synaptic Function by the Metabolic Hormone, Leptin: Implications for Health and Neurodegenerative Disease. Front Cell Neurosci 2018; 12:340. [PMID: 30386207 PMCID: PMC6198461 DOI: 10.3389/fncel.2018.00340] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/13/2018] [Indexed: 11/13/2022] Open
Abstract
The role of the endocrine hormone leptin in controlling energy homeostasis in the hypothalamus are well documented. However the CNS targets for leptin are not restricted to the hypothalamus as a high density of leptin receptors are also expressed in several parts of the brain involved in higher cognitive functions including the hippocampus. Numerous studies have identified that in the hippocampus, leptin has cognitive enhancing actions as exogenous application of this hormone facilitates hippocampal-dependent learning and memory, whereas lack or insensitivity to leptin results in significant memory deficits. Leptin also markedly influences some of the main cellular changes that are involved in learning and memory including NMDA-receptor dependent synaptic plasticity and glutamate receptor trafficking. Like other metabolic hormones, there is a significant decline in neuronal sensitivity to leptin during the ageing process. Indeed, the capacity of leptin to modulate the functioning of hippocampal synapses is substantially reduced in aged compared to adult tissue. Clinical studies have also identified an association between circulating leptin levels and the risk of certain neurodegenerative disorders such as Alzheimer’s disease (AD). In view of this, targeting leptin and/or its receptor/signaling mechanisms may be an innovative approach for developing therapies to treat AD. In support of this, accumulating evidence indicates that leptin has cognitive enhancing and neuroprotective actions in various models of AD. Here we assess recent evidence that supports an important regulatory role for leptin at hippocampal CA1 synapses, and we discuss how age-related alterations in this hormonal system influences neurodegenerative disease.
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Affiliation(s)
- Gemma McGregor
- Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom
| | - Jenni Harvey
- Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom
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18
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de J.R. De-Paula V, Forlenza AS, Forlenza OV. Relevance of gutmicrobiota in cognition, behaviour and Alzheimer’s disease. Pharmacol Res 2018; 136:29-34. [DOI: 10.1016/j.phrs.2018.07.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 05/30/2018] [Accepted: 07/10/2018] [Indexed: 12/22/2022]
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19
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King A, Brain A, Hanson K, Dittmann J, Vickers J, Fernandez-Martos C. Disruption of leptin signalling in a mouse model of Alzheimer's disease. Metab Brain Dis 2018; 33:1097-1110. [PMID: 29546689 DOI: 10.1007/s11011-018-0203-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/15/2018] [Indexed: 12/12/2022]
Abstract
Disruption of leptin signalling has been implicated as playing a role in the development of Alzheimer's disease (AD). Leptin has previously been shown to be affected by amyloid-beta (Aβ)-related signalling; however, pathways that link leptin to the disease pathogenesis have not been determined. To characterize the association between increasing age-dependent Aβ levels with leptin signalling and the vulnerable brain regions in AD, we assessed the mRNA and protein expression profile of leptin and leptin receptor (Ob-Rb) at 9 and 18-month-age in APP/PS1 mice. Immunohistochemical labelling demonstrated that leptin and Ob-Rb proteins were localised to neocortical and hippocampal neurons in APP/PS1 and wildtype (WT) mice. Neuronal leptin and Ob-Rb immunolabelling was more prominent in the neocortex of both groups at 9 month of age, while, at 18 months, labelling was reduced in the hippocampus of APP/PS1 mice relative to WT. Immunoblotting analysis demonstrated decreased hippocampal leptin levels, concomitantly with an increased Ob-Rb levels, in APP/PS1 mice compared with WT controls at 18 month of age. While no leptin mRNA was found in either of the groups analysed, Ob-Rb mRNA was significantly decreased in the hippocampus of APP/PS1 mice at both ages analysed. In addition, a significant decreased protein kinase B (Akt) activity concomitantly with an upregulation of suppressor of cytokine signaling-3 (SOCS3) and protein-tyrosine phosphatase 1B (PTP1B) transcripts was present. Thus, these results collectively indicate alterations of leptin signalling in the hippocampus of APP/PS1 mice, providing novel insights about the pathways that could link aberrant leptin signaling to the pathological changes of AD.
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Affiliation(s)
- Anna King
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Private Bag 143, Hobart, TAS, 7000, Australia
| | - Anna Brain
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Private Bag 143, Hobart, TAS, 7000, Australia
| | - Kelsey Hanson
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Private Bag 143, Hobart, TAS, 7000, Australia
| | - Justin Dittmann
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Private Bag 143, Hobart, TAS, 7000, Australia
| | - James Vickers
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Private Bag 143, Hobart, TAS, 7000, Australia
| | - Carmen Fernandez-Martos
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Private Bag 143, Hobart, TAS, 7000, Australia.
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21
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Down Syndrome, Obesity, Alzheimer's Disease, and Cancer: A Brief Review and Hypothesis. Brain Sci 2018; 8:brainsci8040053. [PMID: 29587359 PMCID: PMC5924389 DOI: 10.3390/brainsci8040053] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 03/15/2018] [Accepted: 03/22/2018] [Indexed: 12/19/2022] Open
Abstract
Down syndrome (trisomy 21), a complex mix of physical, mental, and biochemical issues, includes an increased risk of Alzheimer’s disease and childhood leukemia, a decreased risk of other tumors, and a high frequency of overweight/obesity. Certain features related to the third copy of chromosome 21 (which carries the APP gene and several anti-angiogenesis genes) create an environment favorable for Alzheimer’s disease and unfavorable for cancer. This environment may be enhanced by two bioactive compounds from fat cells, leptin, and adiponectin. This paper outlines these fat-related disease mechanisms and suggests new avenues of research to reduce disease risk in Down syndrome.
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22
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Leptin and ghrelin: Sewing metabolism onto neurodegeneration. Neuropharmacology 2017; 136:307-316. [PMID: 29248481 DOI: 10.1016/j.neuropharm.2017.12.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 12/11/2017] [Accepted: 12/13/2017] [Indexed: 12/23/2022]
Abstract
Life expectancy has considerably increased over the last decades. The negative consequence of this augmented longevity has been a dramatic increase of age-related chronic neurodegenerative diseases, such as Alzheimer's, Parkinson's and multiple sclerosis. Epidemiology is telling us there exists a strong correlation between the neuronal loss characterizing these disorders and metabolic dysfunction. This review aims at presenting the evidence supporting the existence of a molecular system linking metabolism with neurodegeneration, with a specific focus on the role of two hormones with a key role in the regulatory cross talk between metabolic imbalance and the damage of nervous system: leptin and ghrelin. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'
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23
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McGregor G, Harvey J. Food for thought: Leptin regulation of hippocampal function and its role in Alzheimer's disease. Neuropharmacology 2017; 136:298-306. [PMID: 28987937 DOI: 10.1016/j.neuropharm.2017.09.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 09/27/2017] [Accepted: 09/30/2017] [Indexed: 01/08/2023]
Abstract
Accumulating evidence indicates that diet and body weight are important factors associated with Alzheimer's disease (AD), with a significant increase in AD risk linked to mid-life obesity, and weight loss frequently occurring in the early stages of AD. This has fuelled interest in the hormone leptin, as it is an important hypothalamic regulator of food intake and body weight, but leptin also markedly influences the functioning of the hippocampus; a key brain region that degenerates in AD. Increasing evidence indicates that leptin has cognitive enhancing properties as it facilitates the cellular events that underlie hippocampal-dependent learning and memory. However, significant reductions in leptin's capacity to regulate hippocampal synaptic function occurs with age and dysfunctions in the leptin system are associated with an increased risk of AD. Moreover, leptin is a potential novel target in AD as leptin treatment has beneficial effects in various models of AD. Here we summarise recent advances in leptin neurobiology with particular focus on regulation of hippocampal synaptic function by leptin and the implications of this for neurodegenerative disorders like AD. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'
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Affiliation(s)
- Gemma McGregor
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, United Kingdom
| | - Jenni Harvey
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, United Kingdom.
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24
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Bonfili L, Cecarini V, Berardi S, Scarpona S, Suchodolski JS, Nasuti C, Fiorini D, Boarelli MC, Rossi G, Eleuteri AM. Microbiota modulation counteracts Alzheimer's disease progression influencing neuronal proteolysis and gut hormones plasma levels. Sci Rep 2017; 7:2426. [PMID: 28546539 PMCID: PMC5445077 DOI: 10.1038/s41598-017-02587-2] [Citation(s) in RCA: 277] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/12/2017] [Indexed: 02/07/2023] Open
Abstract
Gut microbiota has a proven role in regulating multiple neuro-chemical pathways through the highly interconnected gut-brain axis. Oral bacteriotherapy thus has potential in the treatment of central nervous system-related pathologies, such as Alzheimer’s disease (AD). Current AD treatments aim to prevent onset, delay progression and ameliorate symptoms. In this work, 3xTg-AD mice in the early stage of AD were treated with SLAB51 probiotic formulation, thereby affecting the composition of gut microbiota and its metabolites. This influenced plasma concentration of inflammatory cytokines and key metabolic hormones considered therapeutic targets in neurodegeneration. Treated mice showed partial restoration of two impaired neuronal proteolytic pathways (the ubiquitin proteasome system and autophagy). Their cognitive decline was decreased compared with controls, due to a reduction in brain damage and reduced accumulation of amyloid beta aggregates. Collectively, our results clearly prove that modulation of the microbiota induces positive effects on neuronal pathways that are able to slow down the progression of Alzheimer’s disease.
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Affiliation(s)
- Laura Bonfili
- School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano, 62032, Camerino, (MC), Italy.
| | - Valentina Cecarini
- School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano, 62032, Camerino, (MC), Italy
| | - Sara Berardi
- School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano, 62032, Camerino, (MC), Italy
| | - Silvia Scarpona
- School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano, 62032, Camerino, (MC), Italy
| | - Jan S Suchodolski
- Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, USA
| | - Cinzia Nasuti
- School of Pharmacy, Pharmacology Unit, University of Camerino, via Madonna delle Carceri, 62032, Camerino, (MC), Italy
| | - Dennis Fiorini
- Division of Chemistry, School of Science and Technology, University of Camerino, I-62032, Camerino, MC, Italy
| | - Maria Chiara Boarelli
- Division of Chemistry, School of Science and Technology, University of Camerino, I-62032, Camerino, MC, Italy
| | - Giacomo Rossi
- School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano, 62032, Camerino, (MC), Italy
| | - Anna Maria Eleuteri
- School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano, 62032, Camerino, (MC), Italy
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Fernandez-Martos CM, Atkinson RAK, Chuah MI, King AE, Vickers JC. Combination treatment with leptin and pioglitazone in a mouse model of Alzheimer's disease. ALZHEIMERS & DEMENTIA-TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2016; 3:92-106. [PMID: 29067321 PMCID: PMC5651376 DOI: 10.1016/j.trci.2016.11.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Combination therapy approaches may be necessary to address the many facets of pathologic change in the brain in Alzheimer's disease (AD). The drugs leptin and pioglitazone have previously been shown individually to have neuroprotective and anti-inflammatory actions, respectively, in animal models. METHODS We studied the impact of combined leptin and pioglitazone treatment in 6-month-old APP/PS1 (APPswe/PSEN1dE9) transgenic AD mouse model. RESULTS We report that an acute 2-week treatment with combined leptin and pioglitazone resulted in a reduction of spatial memory deficits (Y maze) and brain β-amyloid levels (soluble β-amyloid and amyloid plaque burden) relative to vehicle-treated animals. Combination treatment was also associated with amelioration in plaque-associated neuritic pathology and synapse loss, and also a significantly reduced neocortical glial response. DISCUSSION Combination therapy with leptin and pioglitazone ameliorates pathologic changes in APP/PS1 mice and may represent a potential treatment approach for AD.
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Affiliation(s)
- Carmen M Fernandez-Martos
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Hobart, Tasmania, Australia
| | - Rachel A K Atkinson
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Hobart, Tasmania, Australia
| | - Meng I Chuah
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Hobart, Tasmania, Australia
| | - Anna E King
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Hobart, Tasmania, Australia
| | - James C Vickers
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Hobart, Tasmania, Australia
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McGuire MJ, Ishii M. Leptin Dysfunction and Alzheimer's Disease: Evidence from Cellular, Animal, and Human Studies. Cell Mol Neurobiol 2016; 36:203-17. [PMID: 26993509 DOI: 10.1007/s10571-015-0282-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/01/2015] [Indexed: 12/13/2022]
Abstract
There is accumulating evidence from epidemiological studies that changes in body weight are associated with Alzheimer's disease (AD) from mid-life obesity increasing the risk of developing AD to weight loss occurring at the earliest stages of AD. Therefore, factors that regulate body weight are likely to influence the development and progression of AD. The adipocyte-derived hormone leptin has emerged as a major regulator of body weight mainly by activating hypothalamic neural circuits. Leptin also has several pleotropic effects including regulating cognitive function and having neuroprotective effects, suggesting a potential link between leptin and AD. Here, we will examine the relationship between leptin and AD by reviewing the recent evidence from cellular and animal models to human studies. We present a model where leptin has a bidirectional role in AD. Not only can alterations in leptin levels and function worsen cognitive decline and progression of AD pathology, but AD pathology, in of itself, can disrupt leptin signaling, which together would lead to a downward spiral of progressive neurodegeneration and worsening body weight and systemic metabolic deficits. Collectively, these studies serve as a framework to highlight the importance of understanding the molecular mechanisms underlying the body weight and systemic metabolic deficits in AD, which has the potential to open new avenues that may ultimately lead to novel therapeutic targets and diagnostic tools.
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Affiliation(s)
- Matthew J McGuire
- Feil Family Brain and Mind Research Institute, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY, 10065, USA
| | - Makoto Ishii
- Feil Family Brain and Mind Research Institute, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY, 10065, USA.
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27
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Conti E, Nacinovich R, Bomba M, Raggi ME, Neri F, Ferrarese C, Tremolizzo L. Beta-amyloid plasma levels in adolescents with anorexia nervosa of the restrictive type. Neuropsychobiology 2016; 71:154-7. [PMID: 25998413 DOI: 10.1159/000381399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/04/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Reduced plasma leptin and elevated homocysteine (Hcy) are known to lead to increased β-amyloid (Aβ) production, besides being hallmarks of anorexia nervosa (AN) of the restrictive type. AN subjects display several neuropsychiatric manifestations, which may entail Aβ-mediated altered synaptic functions. The aim of this study consisted in assessing Aβ plasma levels in AN patients. METHODS A total of 24 adolescent female AN outpatients were recruited together with 12 age-comparable healthy controls. For each subject we assessed Aβ40 and leptin plasma levels, as well as APOE genotype. Hcy plasma levels were also determined in AN patients who underwent clinical characterization, including the Eating Disorder Inventory-3 (EDI-3), the Children's Depression Inventory (CDI) and the estimation of the speed of BMI loss (DPI, disease progression index). RESULTS Plasma Aβ40 levels were similar between patients and controls, while a marked reduction was observed for leptin (∼80%) in AN patients. Aβ40 plasma levels failed to correlate with leptin, while a linear correlation was present with Hcy (r = 0.50, p < 0.03). Examined clinical features were not related with Aβ40 plasma levels, with the only exception of the DPI (r = 0.47, p < 0.03). CONCLUSION This exploratory study does not support a significant role for altered Aβ production in AN-associated dysfunctions. Further studies are required to clarify whether exceptions to this conclusion can be drawn for those patients expressing significantly elevated Hcy plasma levels or for those progressing more rapidly.
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Affiliation(s)
- Elisa Conti
- Neurology Unit, Milan Center for Neuroscience (Neuro-MI), University of Milano-Bicocca, Monza, Italy
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28
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Platt TL, Beckett TL, Kohler K, Niedowicz DM, Murphy MP. Obesity, diabetes, and leptin resistance promote tau pathology in a mouse model of disease. Neuroscience 2015; 315:162-74. [PMID: 26701291 DOI: 10.1016/j.neuroscience.2015.12.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 12/04/2015] [Accepted: 12/04/2015] [Indexed: 01/22/2023]
Abstract
Obesity and type 2 diabetes mellitus (T2DM) convey an increased risk for developing dementia. The microtubule-associated protein tau is implicated in neurodegenerative disease by undergoing hyperphosphorylation and aggregation, leading to cytotoxicity and neurodegeneration. Enzymes involved in the regulation of tau phosphorylation, such as GSK3β, are tightly associated with pathways found to be dysregulated in T2DM. We have shown previously that leptin-resistant mice, which develop obesity and a diabetic phenotype, display elevated levels of tau phosphorylation. Here we show cells cultured with leptin, an adipokine shown to have neuroprotective effects, reduces tau phosphorylation. To explore how this mechanism works in vivo we transduced an existing diabetic mouse line (Lepr(db/db)) with a tau mutant (tau(P301L)) via adeno-associated virus (AAV). The resulting phenotype included a striking increase in tau phosphorylation and the number of neurofibrillary tangles (NFTs) found within the hippocampus. We conclude that leptin resistance-induced obesity and diabetes accelerates the development of tau pathology. This model of metabolic dysfunction and tauopathy provides a new system in which to explore the mechanisms underlying the ways in which leptin resistance and diabetes influence development of tau pathology, and may ultimately be related to the development of NFTs.
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Affiliation(s)
- T L Platt
- Department of Molecular and Cellular Biochemistry, University of Kentucky, United States
| | - T L Beckett
- Sanders Brown Center on Aging, University of Kentucky, United States
| | - K Kohler
- Sanders Brown Center on Aging, University of Kentucky, United States
| | - D M Niedowicz
- Department of Molecular and Cellular Biochemistry, University of Kentucky, United States; Sanders Brown Center on Aging, University of Kentucky, United States
| | - M P Murphy
- Department of Molecular and Cellular Biochemistry, University of Kentucky, United States; Sanders Brown Center on Aging, University of Kentucky, United States.
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Association between Plasma Leptin and Estrogen in Female Patients of Amnestic Mild Cognitive Impairment. DISEASE MARKERS 2015; 2015:450237. [PMID: 26693203 PMCID: PMC4677007 DOI: 10.1155/2015/450237] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 10/28/2015] [Accepted: 11/01/2015] [Indexed: 11/18/2022]
Abstract
Increasing evidences suggested the association between leptin and cognitive functions. Estrogen is an important factor that regulates the production and metabolism of leptin. However, little is known about the relationship between leptin and estrogen in mild cognitive impairment (MCI). Plasma levels of leptin, total estradiol, and β-amyloid protein (Aβ) were measured in a total of 23 female amnestic MCI (aMCI) patients and 19 female cognitively normal controls. This study showed that female aMCI patients had lower plasma levels of leptin and higher levels of estradiol compared to female normal controls. Leptin and estradiol levels were not correlated with cognitive performances or plasma Aβ levels in either aMCI patients or normal controls. There was a significant negative correlation between leptin and estrogen in female aMCI patients (r = -0.633, p = 0.002) but not in female normal controls. The potential mechanisms of this disease-stage-specific association between leptin and estrogen need further investigations.
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Magalhães CA, Carvalho MG, Sousa LP, Caramelli P, Gomes KB. Leptin in Alzheimer's disease. Clin Chim Acta 2015; 450:162-8. [PMID: 26279362 DOI: 10.1016/j.cca.2015.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/08/2015] [Accepted: 08/12/2015] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of progressive dementia in the elderly population. AD is histologically characterized by accumulation of amyloid-β protein (Aβ) on extracellular plaques and deposition of hyperphosphorylated tau protein in intracellular neurofibrillary tangles. Several studies have shown that obesity may precede dementia and that lifestyle factors play a critical role in the onset of AD. Furthermore, accumulating evidence indicates that obesity is an independent risk factor for developing AD. In this scenario, the understanding of the role of adipose tissue in brain health is essential to clarify the establishment of demential processes. The objective of this work was to review studies regarding leptin, an anorexigenic peptide hormone synthesized in adipocytes, in the context of dementia. Some authors proposed that leptin evaluation might be a better predictor of dementia than traditional anthropometric measures. Leptin, once established as a biomarker, could enhance the understanding of late-onset AD risk over the life course, as well as the clinical progression of prodromal state to manifested AD. Other studies have proposed that leptin presents neuroprotective activities, which could be explained by inhibiting the amyloidogenic process, reducing the levels of tau protein phosphorylation and improving the cognitive function.
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Affiliation(s)
- C A Magalhães
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - M G Carvalho
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - L P Sousa
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - P Caramelli
- Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - K B Gomes
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil..
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West S, Bhugra P. Emerging drug targets for Aβ and tau in Alzheimer's disease: a systematic review. Br J Clin Pharmacol 2015; 80:221-34. [PMID: 25753046 DOI: 10.1111/bcp.12621] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 02/24/2015] [Accepted: 03/02/2015] [Indexed: 01/20/2023] Open
Abstract
AIMS Currently, treatment for Alzheimer's disease (AD) focuses on the cholinergic hypothesis and provides limited symptomatic effects. Research currently focuses on other factors that are thought to contribute to AD development such as tau proteins and Aβ deposits, and how modification of the associated pathology affects outcomes in patients. This systematic review summarizes and appraises the evidence for the emerging drugs affecting Aβ and tau pathology in AD. METHODS A comprehensive, systematic online database search was conducted using the databases ScienceDirect and PubMed to include original research articles. A systematic review was conducted following a minimum set of standards, as outlined by The PRISMA Group . Specific inclusion and exclusion criteria were followed and studies fitting the criteria were selected. No human trials were included in this review. In vitro and in vivo AD models were used to assess efficacy to ensure studied agents were emerging targets without large bodies of evidence. RESULTS The majority of studies showed statistically significant improvement (P < 0.05) of Aβ and/or tau pathology, or cognitive effects. Many studies conducted in AD animal models have shown a reduction in Aβ peptide burden and a reduction in tau phosphorylation post-intervention. This has the potential to reduce plaque formation and neuronal degeneration. CONCLUSIONS There are many emerging targets showing promising results in the effort to modify the pathological effects associated with AD. Many of the trials also provided evidence of the clinical effects of such drugs reducing pathological outcomes, which was often demonstrated as an improvement of cognition.
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Affiliation(s)
- Sophie West
- Sunderland Pharmacy School, Department of Pharmacy, Health and Wellbeing, The University of Sunderland, City Campus, Chester Road, Sunderland, SR1 3SD, United Kingdom
| | - Praveen Bhugra
- Sunderland Pharmacy School, Department of Pharmacy, Health and Wellbeing, The University of Sunderland, City Campus, Chester Road, Sunderland, SR1 3SD, United Kingdom
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Wan Z, Mah D, Simtchouk S, Kluftinger A, Little JP. Human adipose tissue conditioned media from lean subjects is protective against H2O2 induced neurotoxicity in human SH-SY5Y neuronal cells. Int J Mol Sci 2015; 16:1221-31. [PMID: 25569096 PMCID: PMC4307300 DOI: 10.3390/ijms16011221] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/24/2014] [Indexed: 01/15/2023] Open
Abstract
Adipose tissue secretes numerous hormone-like factors, which are known as adipokines. Adipokine receptors have been identified in the central nervous system but the potential role of adipokine signaling in neuroprotection is unclear. The aim of this study is to determine (1) Whether adipokines secreted from cultured adipose tissue of lean humans is protective against oxidative stress-induced neurotoxicity in human SH-SY5Y neuronal cells; and (2) To explore potential signaling pathways involved in these processes. Adipose tissue conditioned media (ATCM) from healthy lean subjects completely prevented H2O2 induced neurotoxicity, while this effect is lost after heating ATCM. ATCM activated the phosphorylation of ERK1/2, JNK and Akt at serine 308 in SH-SY5Y cells. PD98059 (25 µM), SP600125 (5 µM) and LY29400 (20 µM) partially blocked the protective effects of ATCM against H2O2 induced neurotoxicity. Findings demonstrate that heat-sensitive factors secreted from human adipose tissue of lean subjects are protective against H2O2 induced neurotoxicity and ERK1/2, JNK, and PI3K signaling pathways are involved in these processes. In conclusion, this study demonstrates preliminary but encouraging data to further support that adipose tissue secreted factors from lean human subjects might possess neuroprotective properties and unravel the specific roles of ERK1/2, JNK and PI3K in these processes.
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Affiliation(s)
- Zhongxiao Wan
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada.
| | - Dorrian Mah
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada.
| | - Svetlana Simtchouk
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada.
| | - Andreas Kluftinger
- Department of Surgery, University of British Columbia; General, Laparoscopic, Endocrine and Gastric Band Surgery, 203-3040 Tutt St., Kelowna, BC V1Y 2H5, Canada.
| | - Jonathan P Little
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada.
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Niedowicz DM, Reeves VL, Platt TL, Kohler K, Beckett TL, Powell DK, Lee TL, Sexton TR, Song ES, Brewer LD, Latimer CS, Kraner SD, Larson KL, Ozcan S, Norris CM, Hersh LB, Porter NM, Wilcock DM, Murphy MP. Obesity and diabetes cause cognitive dysfunction in the absence of accelerated β-amyloid deposition in a novel murine model of mixed or vascular dementia. Acta Neuropathol Commun 2014; 2:64. [PMID: 24916066 PMCID: PMC4229778 DOI: 10.1186/2051-5960-2-64] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 06/04/2014] [Indexed: 01/18/2023] Open
Abstract
Mid-life obesity and type 2 diabetes mellitus (T2DM) confer a modest, increased risk for Alzheimer's disease (AD), though the underlying mechanisms are unknown. We have created a novel mouse model that recapitulates features of T2DM and AD by crossing morbidly obese and diabetic db/db mice with APPΔNL/ΔNLx PS1P264L/P264L knock-in mice. These mice (db/AD) retain many features of the parental lines (e.g. extreme obesity, diabetes, and parenchymal deposition of β-amyloid (Aβ)). The combination of the two diseases led to additional pathologies-perhaps most striking of which was the presence of severe cerebrovascular pathology, including aneurysms and small strokes. Cortical Aβ deposition was not significantly increased in the diabetic mice, though overall expression of presenilin was elevated. Surprisingly, Aβ was not deposited in the vasculature or removed to the plasma, and there was no stimulation of activity or expression of major Aβ-clearing enzymes (neprilysin, insulin degrading enzyme, or endothelin-converting enzyme). The db/AD mice displayed marked cognitive impairment in the Morris Water Maze, compared to either db/db or APPΔNLx PS1P264L mice. We conclude that the diabetes and/or obesity in these mice leads to a destabilization of the vasculature, leading to strokes and that this, in turn, leads to a profound cognitive impairment and that this is unlikely to be directly dependent on Aβ deposition. This model of mixed or vascular dementia provides an exciting new avenue of research into the mechanisms underlying the obesity-related risk for age-related dementia, and will provide a useful tool for the future development of therapeutics.
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Cheng X, Wu J, Geng M, Xiong J. Role of synaptic activity in the regulation of amyloid beta levels in Alzheimer's disease. Neurobiol Aging 2013; 35:1217-32. [PMID: 24368087 DOI: 10.1016/j.neurobiolaging.2013.11.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 11/03/2013] [Accepted: 11/24/2013] [Indexed: 01/27/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia. Accumulation of amyloid-beta (Aβ) peptides is regarded as the critical component associated with AD pathogenesis, which is derived from the amyloid precursor protein (APP) cleavage. Recent studies suggest that synaptic activity is one of the most important factors that regulate Aβ levels. It has been found that synaptic activity facilitates APP internalization and influences APP cleavage. Glutamatergic, cholinergic, serotonergic, leptin, adrenergic, orexin, and gamma-amino butyric acid receptors, as well as the activity-regulated cytoskeleton-associated protein (Arc) are all involved in these processes. The present review summarizes the evidence for synaptic activity-modulated Aβ levels and the mechanisms underlying this regulation. Interestingly, the immediate early gene product Arc may also be the downstream signaling molecule of several receptors in the synaptic activity-modulated Aβ levels. Elucidating how Aβ levels are regulated by synaptic activity may provide new insights in both the understanding of the pathogenesis of AD and in the development of therapies to slow down the progression of AD.
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Affiliation(s)
- Xiaofang Cheng
- Department of Physiology, Third Military Medical University, Chongqing, China
| | - Jian Wu
- Department of Physiology, Third Military Medical University, Chongqing, China
| | - Miao Geng
- Institute of Geriatrics, General Hospital of Chinese PLA, Beijing, China
| | - Jiaxiang Xiong
- Department of Physiology, Third Military Medical University, Chongqing, China.
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Liu J, Chi N, Chen H, Zhang J, Bian Y, Cui G, Xiu C. Resistin protection against endogenous Aβ neuronal cytotoxicity from mitochondrial pathway. Brain Res 2013; 1523:77-84. [PMID: 23747409 DOI: 10.1016/j.brainres.2013.05.041] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/23/2013] [Accepted: 05/24/2013] [Indexed: 01/08/2023]
Abstract
Neurotoxicity of amyloid β (Aβ) plays an important role in Alzheimer's disease (AD) pathogenesis. In this study, we researched the potential protective effects of resistin against Aβ neurotoxicity in mouse Neuro2a (N2a) cells transfected with the Swedish amyloid precursor protein (Sw-APP) mutant and Presenilin exon 9 deletion mutant (N2a/D9), which overproduced Aβ with abnormal intracellular Aβ accumulation. The results show increased levels of ROS, NO, protein carbonyls, and 4HNE in N2a/D9 cells, which were attenuated by resistin treatment in a dose dependent manner. We also found that resistin could improve mitochondrial function in N2a/D9 cells through increasing the level of ATP and mitochondrial membrane potential. MTT and LDH assay indicated that N2a/D9 cells show increased vulnerability to H2O2-induced insult, which could be ameliorated by resistin. Mechanically, we found that resistin prevented apoptosis signals through reducing the ratio of Bax/Bcl2, the level of cleaved caspase-3, and attenuating cytochrome C release. Finally, the results demonstrated that resistin did not change the production of Aβ1-40 and Aβ1-42 in N2a/D9 cells, which suggests that the protective effects of resistin are independent of APP metabolism. This raises the possibility of novel AD therapies using resistin.
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Affiliation(s)
- Jie Liu
- The Department of Neurosurgery, Yantai Yu Huang Ding Hospital, Yantai 264000, Shandong, China
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