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Liao MH, Lin YK, Gau FY, Tseng CC, Wu DC, Hsu CY, Chung KH, Li RC, Hu CJ, Then CK, Shen SC. Antidepressant sertraline increases thioflavin-S and Congo red deposition in APPswe/PSEN1dE9 transgenic mice. Front Pharmacol 2024; 14:1260838. [PMID: 38259283 PMCID: PMC10800414 DOI: 10.3389/fphar.2023.1260838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 12/14/2023] [Indexed: 01/24/2024] Open
Abstract
Introduction: Depression is strongly associated with Alzheimer's disease (AD). Antidepressants are commonly used in patients before and after their diagnosis of AD. To date, the relationship between antidepressants and AD remains unclear. Methods: In our study, we administered sertraline or paroxetine to wild type (WT) and APPswe/PSEN1dE9 (APP/PSEN1) transgenic mouse models for up to 12 months. We quantified the drug concentrations using LC-MS/MS analysis and measured serum serotonin level using an ELISA assay. Additionally, we evaluated the amyloid burdens through thioflavin-S and Congo red stainings, and recognition memory using the novel object recognition test. Results: Our findings revealed that mice treated with paroxetine exhibited a significantly higher level of weight gain compared to the control group and increased mortality in APP/PSEN1 mice. After 12 months of antidepressant treatment, the sertraline level was measured at 289.8 ng/g for cerebellum, while the paroxetine level was 792.9 ng/g for cerebellum. Sertraline significantly increased thioflavin-S and Congo red depositions, along with gliosis, in both isocortex and hippocampus of APP/PSEN1 mice compared to the control group. Both antidepressants also led to a decreased recognition index in APP/PSEN1 mice. Conclusion: These findings suggest a potential role of sertraline in AD pathogenesis, emphasizing the need to reassess the use of these antidepressants in patients with AD.
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Affiliation(s)
- Ming-Hsuan Liao
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yen-Kuang Lin
- Graduate Institute of Athletics and Coaching Science, National Taiwan Sport University, Taoyuan, Taiwan
| | - Fong-Ying Gau
- School of Nursing, College of Nursing, Taipei Medical University, Taipei, Taiwan
| | - Chun-Che Tseng
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Da-Chih Wu
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chu-Yuan Hsu
- School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei, Taiwan
| | - Kuo-Hsuan Chung
- Department of Psychiatry and Psychiatric Research Center, Taipei Medical University Hospital, Taipei, Taiwan
- Department of Psychiatry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Rung-Chi Li
- Division of Allergy and Immunology, University of Virginia, Charlottesville, VA, United States
| | - Chaur-Jong Hu
- Department of Neurology, Shuang Ho Hospital, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chee Kin Then
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
- Department of Radiation Oncology, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan
| | - Shing-Chuan Shen
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
- International Master/Ph.D. Program in Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Department of Dermatology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
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Reyna NC, Clark BJ, Hamilton DA, Pentkowski NS. Anxiety and Alzheimer's disease pathogenesis: focus on 5-HT and CRF systems in 3xTg-AD and TgF344-AD animal models. Front Aging Neurosci 2023; 15:1251075. [PMID: 38076543 PMCID: PMC10699143 DOI: 10.3389/fnagi.2023.1251075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/25/2023] [Indexed: 02/12/2024] Open
Abstract
Dementia remains one of the leading causes of morbidity and mortality in older adults. Alzheimer's disease (AD) is the most common type of dementia, affecting over 55 million people worldwide. AD is characterized by distinct neurobiological changes, including amyloid-beta protein deposits and tau neurofibrillary tangles, which cause cognitive decline and subsequent behavioral changes, such as distress, insomnia, depression, and anxiety. Recent literature suggests a strong connection between stress systems and AD progression. This presents a promising direction for future AD research. In this review, two systems involved in regulating stress and AD pathogenesis will be highlighted: serotonin (5-HT) and corticotropin releasing factor (CRF). Throughout the review, we summarize critical findings in the field while discussing common limitations with two animal models (3xTg-AD and TgF344-AD), novel pharmacotherapies, and potential early-intervention treatment options. We conclude by highlighting promising future pharmacotherapies and translational animal models of AD and anxiety.
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Affiliation(s)
- Nicole C. Reyna
- Department of Psychology, University of New Mexico, Albuquerque, NM, United States
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3
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Collins HM, Pinacho R, Tam SKE, Sharp T, Bannerman DM, Peirson SN. Continuous home cage monitoring of activity and sleep in mice during repeated paroxetine treatment and discontinuation. Psychopharmacology (Berl) 2023; 240:2403-2418. [PMID: 37584734 PMCID: PMC10593620 DOI: 10.1007/s00213-023-06442-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 07/27/2023] [Indexed: 08/17/2023]
Abstract
RATIONALE Non-invasive home cage monitoring is emerging as a valuable tool to assess the effects of experimental interventions on mouse behaviour. A field in which these techniques may prove useful is the study of repeated selective serotonin reuptake inhibitor (SSRI) treatment and discontinuation. SSRI discontinuation syndrome is an under-researched condition that includes the emergence of sleep disturbances following treatment cessation. OBJECTIVES We used passive infrared (PIR) monitoring to investigate changes in activity, sleep, and circadian rhythms during repeated treatment with the SSRI paroxetine and its discontinuation in mice. METHODS Male mice received paroxetine (10 mg/kg/day, s.c.) for 12 days, then were swapped to saline injections for a 13 day discontinuation period and compared to mice that received saline injections throughout. Mice were continuously tracked using the Continuous Open Mouse Phenotyping of Activity and Sleep Status (COMPASS) system. RESULTS Repeated paroxetine treatment reduced activity and increased behaviourally-defined sleep in the dark phase. These effects recovered to saline-control levels within 24 h of paroxetine cessation, yet there was also evidence of a lengthening of sleep bouts in the dark phase for up to a week following discontinuation. CONCLUSIONS This study provides the first example of how continuous non-invasive home cage monitoring can be used to detect objective behavioural changes in activity and sleep during and after drug treatment in mice. These data suggest that effects of paroxetine administration reversed soon after its discontinuation but identified an emergent change in sleep bout duration, which could be used as a biomarker in future preclinical studies to prevent or minimise SSRI discontinuation symptoms.
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Affiliation(s)
- Helen M Collins
- University Department of Pharmacology, Oxford, UK
- University Department of Experimental Psychology, Oxford, UK
| | - Raquel Pinacho
- University Department of Pharmacology, Oxford, UK
- University Department of Experimental Psychology, Oxford, UK
| | - S K Eric Tam
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Trevor Sharp
- University Department of Pharmacology, Oxford, UK
| | | | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK.
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Wang J, Mei Y, Zhang X, Wei X, Zhang Y, Wang D, Huang J, Zhu K, Peng G, Sun B. Aberrant serotonergic signaling contributes to the hyperexcitability of CA1 pyramidal neurons in a mouse model of Alzheimer's disease. Cell Rep 2023; 42:112152. [PMID: 36821438 DOI: 10.1016/j.celrep.2023.112152] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 11/29/2022] [Accepted: 02/08/2023] [Indexed: 02/24/2023] Open
Abstract
Hyperactivity of pyramidal neurons (PNs) in CA1 is an early event in Alzheimer's disease. However, factors accounting for the hyperactivity of CA1 PNs remain to be completely investigated. In the present study, we report that the serotonergic signaling is abnormal in the hippocampus of hAPP-J20 mice. Interestingly, chemogenetic activation of serotonin (5-hydroxytryptamine; 5-HT) neurons in the median raphe nucleus (MRN) attenuates the activity of CA1 PNs in hAPP-J20 mice by regulating the intrinsic properties or inhibitory synaptic transmission of CA1 PNs through 5-HT3aR and/or 5-HT1aR. Furthermore, activating MRN 5-HT neurons improves memory in hAPP-J20 mice, and this effect is mediated by 5-HT3aR and 5-HT1aR. Direct activation of 5-HT3aR and 5-HT1aR with their selective agonists also improves the memory of hAPP-J20 mice. Together, we identify the impaired 5-HT/5-HT3aR and/or 5-HT/5-HT1aR signaling as pathways contributing to the hyperexcitability of CA1 PNs and the impaired cognition in hAPP-J20 mice.
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Affiliation(s)
- Jing Wang
- Department of Neurobiology and Department of Anesthesiology, the Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yufei Mei
- Department of Neurobiology and Department of Anesthesiology, the Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; Brain Science and Advanced Technology Institute, School of Medicine, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China.
| | - Xiaoqin Zhang
- Department of Physiology and Pharmacology, Medical School of Ningbo University, Ningbo, Zhejiang 315211, China
| | - Xiaojie Wei
- Department of Neurobiology and Department of Anesthesiology, the Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yiping Zhang
- Department of Neurobiology and Department of Anesthesiology, the Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Dongpi Wang
- Department of Anesthesiology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310003, China
| | - Jinjin Huang
- Department of Anesthesiology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310003, China
| | - Keqing Zhu
- National Human Brain Bank for Health and Disease and Department of Neurology in Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Guoping Peng
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, China.
| | - Binggui Sun
- Department of Neurobiology and Department of Anesthesiology, the Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China.
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Delport A, Hewer R. The amyloid precursor protein: a converging point in Alzheimer's disease. Mol Neurobiol 2022; 59:4501-4516. [PMID: 35579846 DOI: 10.1007/s12035-022-02863-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 04/30/2022] [Indexed: 11/30/2022]
Abstract
The decades of evidence that showcase the role of amyloid precursor protein (APP), and its fragment amyloidβ (Aβ), in Alzheimer's disease (AD) pathogenesis are irrefutable. However, the absolute focus on the single APP metabolite Aβ as the cause for AD has resulted in APP and its other fragments that possess toxic propensity, to be overlooked as targets for treatment. The complexity of its processing and its association with systematic metabolism suggests that, if misregulated, APP has the potential to provoke an array of metabolic dysfunctions. This review discusses APP and several of its cleaved products with a particular focus on their toxicity and ability to disrupt healthy cellular function, in relation to AD development. We subsequently argue that the reduction of APP, which would result in a concurrent decrease in Aβ as well as all other toxic APP metabolites, would alleviate the toxic environment associated with AD and slow disease progression. A discussion of those drug-like compounds already identified to possess this capacity is also included.
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Affiliation(s)
- Alexandré Delport
- Discipline of Biochemistry, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, 3201, South Africa.
| | - Raymond Hewer
- Discipline of Biochemistry, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, 3201, South Africa
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Sivasaravanaparan M, Olesen LØ, Severino M, von Linstow MCU, Lambertsen KL, Gramsbergen JB, Hasselstrøm J, Metaxas A, Wiborg O, Finsen B. Efficacy of Chronic Paroxetine Treatment in Mitigating Amyloid Pathology and Microgliosis in APPSWE/PS1ΔE9 Transgenic Mice. J Alzheimers Dis 2022; 87:685-699. [PMID: 35342093 DOI: 10.3233/jad-220019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Modulation of serotonergic signaling by treatment with selective serotonin reuptake inhibitors (SSRIs) has been suggested to mitigate amyloid-β (Aβ) pathology in Alzheimer's disease, in addition to exerting an anti-depressant action. OBJECTIVE To investigate the efficacy of chronic treatment with the SSRI paroxetine, in mitigating Aβ pathology and Aβ plaque-induced microgliosis in the hippocampus of 18-month-old APPswe/PS1 ΔE9 mice. METHODS Plaque-bearing APPswe/PS1 ΔE9 and wildtype mice were treated with paroxetine per os at a dose of 5 mg/kg/day, from 9 to 18 months of age. The per os treatment was monitored by recording of the body weights and serum paroxetine concentrations, and by assessment of the serotonin transporter occupancy by [3H]DASB-binding in wildtype mice. Additionally, 5,7-dihydroxytryptamine was administered to 9-month-old APPswe/PS1 ΔE9 mice, to examine the effect of serotonin depletion on Aβ pathology. Aβ pathology was evaluated by Aβ plaque load estimation and the Aβ 42/Aβ 40 ratio by ELISA. RESULTS Paroxetine treatment led to > 80% serotonin transporter occupancy. The treatment increased the body weight of wildtype mice, but not of APPswe/PS1 ΔE9 mice. The treatment had no effect on the Aβ plaque load (p = 0.39), the number and size of plaques, or the Aβ plaque-induced increases in microglial numbers in the dentate gyrus. Three months of serotonin depletion did not significantly impact the Aβ plaque load or Aβ 42/Aβ 40 ratio in APPswe/PS1 ΔE9 mice at 12 months. CONCLUSION Our results show that chronic treatment with the SSRI paroxetine does not mitigate Aβ pathology and Aβ plaque-induced microgliosis in the hippocampus of APPswe/PS1 ΔE9 mice.
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Affiliation(s)
- Mithula Sivasaravanaparan
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark
| | | | - Maurizio Severino
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark
| | | | - Kate Lykke Lambertsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark.,Department of Neurology, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, BRIDGE-Brain Research-Inter-Disciplinary Guided Excellence, University of Southern Denmark, Denmark
| | - Jan Bert Gramsbergen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark
| | | | - Athanasios Metaxas
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark.,Department of Life Sciences, School of Science, European University Cyprus, Nicosia, Cyprus
| | - Ove Wiborg
- Department of Clinical Medicine, Aarhus University Hospital, Denmark.,Department of Health Science and Technology, Aalborg University, Denmark
| | - Bente Finsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark.,Department of Clinical Research, BRIDGE-Brain Research-Inter-Disciplinary Guided Excellence, University of Southern Denmark, Denmark
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7
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Aaldijk E, Vermeiren Y. The role of serotonin within the microbiota-gut-brain axis in the development of Alzheimer's disease: A narrative review. Ageing Res Rev 2022; 75:101556. [PMID: 34990844 DOI: 10.1016/j.arr.2021.101556] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/20/2021] [Accepted: 12/30/2021] [Indexed: 12/26/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia, accounting for more than 50 million patients worldwide. Current evidence suggests the exact mechanism behind this devastating disease to be of multifactorial origin, which seriously complicates the quest for an effective disease-modifying therapy, as well as impedes the search for strategic preventative measures. Of interest, preclinical studies point to serotonergic alterations, either induced via selective serotonin reuptake inhibitors or serotonin receptor (ant)agonists, in mitigating AD brain neuropathology next to its clinical symptoms, the latter being supported by a handful of human intervention trials. Additionally, a substantial amount of preclinical trials highlight the potential of diet, fecal microbiota transplantations, as well as pre- and probiotics in modulating the brain's serotonergic neurotransmitter system, starting from the gut. Whether such interventions could truly prevent, reverse or slow down AD progression likewise, should be initially tested in preclinical studies with AD mouse models, including sufficient analytical measurements both in gut and brain. Thereafter, its potential therapeutic effect could be confirmed in rigorously randomized controlled trials in humans, preferentially across the Alzheimer's continuum, but especially from the prodromal up to the mild stages, where both high adherence to such therapies, as well as sufficient room for noticeable enhancement are feasible still. In the end, such studies might aid in the development of a comprehensive approach to tackle this complex multifactorial disease, since serotonin and its derivatives across the microbiota-gut-brain axis might serve as possible biomarkers of disease progression, next to forming a valuable target in AD drug development. In this narrative review, the available evidence concerning the orchestrating role of serotonin within the microbiota-gut-brain axis in the development of AD is summarized and discussed, and general considerations for future studies are highlighted.
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Affiliation(s)
- Emma Aaldijk
- Division of Human Nutrition and Health, Chair Group of Nutritional Biology, Wageningen University & Research (WUR), Wageningen, Netherlands
| | - Yannick Vermeiren
- Division of Human Nutrition and Health, Chair Group of Nutritional Biology, Wageningen University & Research (WUR), Wageningen, Netherlands; Faculty of Medicine & Health Sciences, Translational Neurosciences, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium.
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Cope ZA, Murai T, Sukoff Rizzo SJ. Emerging Electroencephalographic Biomarkers to Improve Preclinical to Clinical Translation in Alzheimer's Disease. Front Aging Neurosci 2022; 14:805063. [PMID: 35250541 PMCID: PMC8891809 DOI: 10.3389/fnagi.2022.805063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/26/2022] [Indexed: 11/18/2022] Open
Abstract
Continually emerging data indicate that sub-clinical, non-convulsive epileptiform activity is not only prevalent in Alzheimer's disease (AD) but is detectable early in the course of the disease and predicts cognitive decline in both humans and animal models. Epileptiform activity and other electroencephalographic (EEG) measures may hold powerful, untapped potential to improve the translational validity of AD-related biomarkers in model animals ranging from mice, to rats, and non-human primates. In this review, we will focus on studies of epileptiform activity, EEG slowing, and theta-gamma coupling in preclinical models, with particular focus on its role in cognitive decline and relevance to AD. Here, each biomarker is described in the context of the contemporary literature and recent findings in AD relevant animal models are discussed.
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Affiliation(s)
| | | | - Stacey J. Sukoff Rizzo
- Aging Institute, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
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von Linstow CU, Waider J, Bergh MSS, Anzalone M, Madsen C, Nicolau AB, Wirenfeldt M, Lesch KP, Finsen B. The Combined Effects of Amyloidosis and Serotonin Deficiency by Tryptophan Hydroxylase-2 Knockout Impacts Viability of the APP/PS1 Mouse Model of Alzheimer’s Disease. J Alzheimers Dis 2021; 85:1283-1300. [DOI: 10.3233/jad-210581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Background: A decline of brain serotonin (5-HT) is held responsible for the changes in mood that can be observed in Alzheimer’s disease (AD). However, 5-HT’ergic signaling is also suggested to reduce the production of pathogenic amyloid-4β (Aβ). Objective: To investigate the effect of targeted inactivation of tryptophan hydroxylase-2 (Tph2), which is essential for neuronal 5-HT synthesis, on amyloidosis in amyloid precursor protein (APP)swe/presenilin 1 (PS1) ΔE9 transgenic mice. Methods: Triple-transgenic (3xTg) APP/PS1 mice with partial (+/-) or complete Tph2 knockout (–/–) were allowed to survive until 6 months old with APP/PS1, Tph2–/–, and wildtype mice. Survival and weight were recorded. Levels of Aβ 42/40/38, soluble APPα (sAβPPα) and sAβPPβ, and cytokines were analyzed by mesoscale, neurotransmitters by mass spectrometry, and gene expression by quantitative PCR. Tph2, microglia, and Aβ were visualized histologically. Results: Tph2 inactivation in APP/PS1 mice significantly reduced viability, without impacting soluble and insoluble Aβ 42 and Aβ 40 in neocortex and hippocampus, and with only mild changes of soluble Aβ 42/Aβ 40. However, sAβPPα and sAβPPβ in hippocampus and Aβ 38 and Aβ 40 in cerebrospinal fluid were reduced. 3xTg–/–mice were devoid of Tph2 immunopositive fibers and 5-HT. Cytokines were unaffected by genotype, as were neocortical TNF, HTR2a and HTR2b mRNA levels in Tph2–/– mice. Microglia clustered around Aβ plaques regardless of genotype. Conclusion: The results suggest that Tph2 inactivation influences AβPP processing, at least in the hippocampus, although levels of Aβ are unchanged. The reduced viability of 3xTg–/–mice could indicate that 5-HT protects against the seizures that can impact the viability of APP/PS1 mice.
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Affiliation(s)
- Christian Ulrich von Linstow
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
- Center for Neurodegenerative Science, Van Andel Institute, Grand Rapids, MI, USA
| | - Jonas Waider
- Division of Molecular Psychiatry, Center of Mental Health, University of Wuerzburg, Würzburg, Germany
| | - Marianne Skov-Skov Bergh
- Section for Drug Abuse Research, Department of Forensic Sciences, Division of Laboratory Medicine, Oslo University Hospital, Oslo, Norway
| | - Marco Anzalone
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
- BRIDGE - Brain Research-Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
| | - Cecilie Madsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
- BRIDGE - Brain Research-Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
| | - Aina Battle Nicolau
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
| | - Martin Wirenfeldt
- BRIDGE - Brain Research-Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
- Department of Pathology, Institute of Clinical Science, Odense University Hospital, Denmark
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Center of Mental Health, University of Wuerzburg, Würzburg, Germany
- Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
- Department of Neuropsychology and Psychiatry, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Maastricht, The Netherlands
| | - Bente Finsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
- BRIDGE - Brain Research-Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
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Ashford JW. Treatment of Alzheimer's Disease: Trazodone, Sleep, Serotonin, Norepinephrine, and Future Directions. J Alzheimers Dis 2020; 67:923-930. [PMID: 30776014 PMCID: PMC6398534 DOI: 10.3233/jad-181106] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In this issue, an article by La et al. provides evidence that trazodone delayed cognitive decline in 25 participants with Alzheimer's disease (AD), mild cognitive impairment, or normal cognition. For participants considered to have AD pathology, trazodone non-users declined at a rate 2.4 times greater than those taking trazodone for sleep over a 4-year period. In the analysis of sleep complaints, the relationship between trazodone, a widely used medication for sleep problems in the elderly, and cognition was associated with subjective improvement of sleep disruption. Due to the design of the study, it was not possible to prove that the benefit of slowing cognitive decline was due specifically to the improvement in sleep. However, trazodone uniquely improves the deeper phases of slow-wave sleep. Other sedative medications are generally associated with worse cognitive function over time, and they do not improve sleep characteristics as does trazodone. Trazodone has a variety of effects on several monoaminergic mechanisms: a potent serotonin 5-HT2A and α1-adrenergic receptor antagonist, a weak serotonin reuptake inhibitor, and a weak antihistamine or histamine H1 receptor inverse agonist. Because of the potential importance of this finding, further discussion is provided on the roles that trazodone may play in the modulation of monoamines, cognition, and the development of AD. If trazodone really does provide such a dramatic slowing in the development of dementia associated with AD, a great deal more research on trazodone is needed, including environmental and behavioral factors related to improvement of sleep, energy management, and neuroplasticity.
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Affiliation(s)
- John Wesson Ashford
- War Related Illness and Injury Study Center, VA Palo Alto Health Care System and Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, CA, USA
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The Challenge of Antidepressant Therapeutics in Alzheimer's Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020. [PMID: 32304037 DOI: 10.1007/978-3-030-42667-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
The link between depression and Alzheimer's disease (AD) is controversial, because it is not clear if depression is an independent risk factor for the disease or a prodromal symptom in the older population. Cerebral amyloid-β (Aβ) peptide deposition is associated with both cognitive symptoms and neuropsychiatric symptoms (NPS), which may be a biological mechanism of compensation. Despite the widespread use of antidepressant therapeutics (30-50% of patients with AD/dementia are on antidepressants), there is mixed evidence regarding the benefits from their use in AD depression. Monoaminergic antidepressant drugs have shown only modest or no clinical benefits. Therefore, it is important to understand the reason of this drug-resistance and the relationship between antidepressant drugs and the Aβ peptide. The goal of the present review is to highlight the etiology of depression in patients affected by AD in comparison to depressive disorders without AD, and to speculate on more appropriate and alternative therapeutics.
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Abstract
Given the failure to develop disease-modifying therapies for Alzheimer’s disease (AD), strategies aiming at preventing or delaying the onset of the disease are being prioritized. While the debate regarding whether depression is an etiological risk factor or a prodrome of AD rages on, a key determining factor may be the timing of depression onset in older adults. There is increasing evidence that untreated early-onset depression is a risk factor and that late-onset depression may be a catalyst of cognitive decline. Data from animal studies have shown a beneficial impact of selective serotonin reuptake inhibitors on pathophysiological biomarkers of AD including amyloid burden, tau deposits and neurogenesis. In humans, studies focusing on subjects with a prior history of depression also showed a delay in the onset of AD in those treated with most selective serotonin reuptake inhibitors. Paroxetine, which has strong anticholinergic properties, was associated with increased mortality and mixed effects on amyloid and tau deposits in mice, as well as increased odds of developing AD in humans. Although most of the data regarding selective serotonin reuptake inhibitors is promising, findings should be interpreted cautiously because of notable methodological heterogeneity between studies. There is thus a need to conduct large scale randomized controlled trials with long follow up periods to clarify the dose-effect relationship of specific serotonergic antidepressants on AD prevention.
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Affiliation(s)
- Bernadette Mdawar
- Department of Psychiatry, American University of Beirut Medical Center, Beirut, Lebanon
| | - Elias Ghossoub
- Department of Psychiatry and Behavioral Neuroscience, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Rita Khoury
- Department of Psychiatry and Behavioral Neuroscience, Saint Louis University School of Medicine, St. Louis, MO, USA
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Metaxas A, Anzalone M, Vaitheeswaran R, Petersen S, Landau AM, Finsen B. Neuroinflammation and amyloid-beta 40 are associated with reduced serotonin transporter (SERT) activity in a transgenic model of familial Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2019; 11:38. [PMID: 31043179 PMCID: PMC6495598 DOI: 10.1186/s13195-019-0491-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/04/2019] [Indexed: 12/18/2022]
Abstract
Background Discrepant and often contradictory results have accumulated regarding the antidepressant and pro-cognitive effects of serotonin transporter (SERT) antagonists in Alzheimer’s disease. Methods To address the discrepancy, we measured the activity and density of SERT in the neocortex of 3–24-month-old APPswe/PS1dE9 and wild-type littermate mice, by using [3H]DASB autoradiography and the [3H]5-HT uptake assay. Levels of soluble amyloid-β (Aβ), and pro-inflammatory cytokines that can regulate SERT function, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF), were measured in parallel. Neuroinflammation in aging APPswe/PS1dE9 mice was further evaluated by [3H]PK11195 autoradiography. Results Decreased SERT density was observed in the parietal and frontal cortex of 18–24-month-old APPswe/PS1dE9 mice, compared to age-matched, wild-type animals. The maximal velocity uptake rate (Vmax) of [3H]5-HT was reduced in neocortical preparations from 20-month-old transgenic vs. wild-type mice. The reduction was observed when the proportion of soluble Aβ40 in the Aβ40/42 ratio increased in the aged transgenic brain. At concentrations compatible with those measured in 20-month-old APPswe/PS1dE9 mice, synthetic human Aβ40, but not Aβ42, reduced the baseline Vmax of [3H]5-HT by ~ 20%. Neuroinflammation in APPswe/PS1dE9 vs. wild-type mice was evidenced by elevated [3H]PK11195 binding levels and increased concentration of IL-1β protein, which preceded the reductions in neocortical SERT density and activity. Age-induced increases in the levels of IL-1β, IL-6, and TNF were observed in both transgenic and wild-type animals. Conclusions The progression of cerebral amyloidosis is associated with neuroinflammation and decreased presynaptic markers of serotonergic integrity and activity. The Aβ40-induced reduction in the uptake kinetics of [3H]5-HT suggests that the activity of SERT, and potentially the effects of SERT antagonism, depend on the levels of interstitial Aβ40.
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Affiliation(s)
- Athanasios Metaxas
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 25, DK-5000, Odense C, Denmark.
| | - Marco Anzalone
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 25, DK-5000, Odense C, Denmark
| | - Ramanan Vaitheeswaran
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 25, DK-5000, Odense C, Denmark
| | - Sussanne Petersen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 25, DK-5000, Odense C, Denmark
| | - Anne M Landau
- Department of Nuclear Medicine & PET Center, Aarhus University and Hospital, Nørrebrogade 44, Building 10G, DK-8000, Aarhus, Denmark.,Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, DK-8240, Risskov, Denmark
| | - Bente Finsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 25, DK-5000, Odense C, Denmark
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14
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Morsy A, Trippier PC. Current and Emerging Pharmacological Targets for the Treatment of Alzheimer's Disease. J Alzheimers Dis 2019; 72:S145-S176. [PMID: 31594236 DOI: 10.3233/jad-190744] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
No cure or disease-modifying therapy for Alzheimer's disease (AD) has yet been realized. However, a multitude of pharmacological targets have been identified for possible engagement to enable drug discovery efforts for AD. Herein, we review these targets comprised around three main therapeutic strategies. First is an approach that targets the main pathological hallmarks of AD: amyloid-β (Aβ) oligomers and hyperphosphorylated tau tangles which primarily focuses on reducing formation and aggregation, and/or inducing their clearance. Second is a strategy that modulates neurotransmitter signaling. Comprising this strategy are the cholinesterase inhibitors and N-methyl-D-aspartate receptor blockade treatments that are clinically approved for the symptomatic treatment of AD. Additional targets that aim to stabilize neuron signaling through modulation of neurotransmitters and their receptors are also discussed. Finally, the third approach comprises a collection of 'sensitive targets' that indirectly influence Aβ or tau accumulation. These targets are proteins that upon Aβ accumulation in the brain or direct Aβ-target interaction, a modification in the target's function is induced. The process occurs early in disease progression, ultimately causing neuronal dysfunction. This strategy aims to restore normal target function to alleviate Aβ-induced toxicity in neurons. Overall, we generally limit our analysis to targets that have emerged in the last decade and targets that have been validated using small molecules in in vitro and/or in vivo models. This review is not an exhaustive list of all possible targets for AD but serves to highlight the most promising and critical targets suitable for small molecule drug intervention.
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Affiliation(s)
- Ahmed Morsy
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, USA
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Paul C Trippier
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, USA
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
- UNMC Center for Drug Discovery, University of Nebraska Medical Center, Omaha, NE, USA
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15
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Thygesen C, Ilkjær L, Kempf SJ, Hemdrup AL, von Linstow CU, Babcock AA, Darvesh S, Larsen MR, Finsen B. Diverse Protein Profiles in CNS Myeloid Cells and CNS Tissue From Lipopolysaccharide- and Vehicle-Injected APP SWE/PS1 ΔE9 Transgenic Mice Implicate Cathepsin Z in Alzheimer's Disease. Front Cell Neurosci 2018; 12:397. [PMID: 30459560 PMCID: PMC6232379 DOI: 10.3389/fncel.2018.00397] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/15/2018] [Indexed: 12/20/2022] Open
Abstract
Neuroinflammation, characterized by chronic activation of the myeloid-derived microglia, is a hallmark of Alzheimer’s disease (AD). Systemic inflammation, typically resulting from infection, has been linked to the progression of AD due to exacerbation of the chronic microglial reaction. However, the mechanism and the consequences of this exacerbation are largely unknown. Here, we mimicked systemic inflammation in AD with weekly intraperitoneal (i.p.) injections of APPSWE/PS1ΔE9 transgenic mice with E. coli lipopolysaccharide (LPS) from 9 to 12 months of age, corresponding to the period with the steepest increase in amyloid pathology. We found that the repeated LPS injections ameliorated amyloid pathology in the neocortex while increasing the neuroinflammatory reaction. To elucidate mechanisms, we analyzed the proteome of the hippocampus from the same mice as well as in unique samples of CNS myeloid cells. The repeated LPS injections stimulated protein pathways of the complement system, retinoid receptor activation and oxidative stress. CNS myeloid cells from transgenic mice showed enrichment in pathways of amyloid-beta clearance and elevated levels of the lysosomal protease cathepsin Z, as well as amyloid precursor protein, apolipoprotein E and clusterin. These proteins were found elevated in the proteome of both LPS and vehicle injected transgenics, and co-localized to CD11b+ microglia in transgenic mice and in primary murine microglia. Additionally, cathepsin Z, amyloid precursor protein, and apolipoprotein E appeared associated with amyloid plaques in neocortex of AD cases. Interestingly, cathepsin Z was expressed in microglial-like cells and co-localized to CD68+ microglial lysosomes in AD cases, and it was expressed in perivascular cells in AD and control cases. Taken together, our results implicate systemic LPS administration in ameliorating amyloid pathology in early-to-mid stage disease in the APPSWE/PS1ΔE9 mouse and attract attention to the potential disease involvement of cathepsin Z expressed in CNS myeloid cells in AD.
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Affiliation(s)
- Camilla Thygesen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.,Brain Research - Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Laura Ilkjær
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Stefan J Kempf
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Anne Louise Hemdrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | - Alicia A Babcock
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Sultan Darvesh
- Department of Medicine (Neurology and Geriatric Medicine) - Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada.,Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, NS, Canada
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Bente Finsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Brain Research - Inter-Disciplinary Guided Excellence, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
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16
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Welcome MO. Current Perspectives and Mechanisms of Relationship between Intestinal Microbiota Dysfunction and Dementia: A Review. Dement Geriatr Cogn Dis Extra 2018; 8:360-381. [PMID: 30483303 PMCID: PMC6244112 DOI: 10.1159/000492491] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/26/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Accumulating data suggest a crucial role of the intestinal microbiota in the development and progression of neurodegenerative diseases. More recently, emerging reports have revealed an association between intestinal microbiota dysfunctions and dementia, a debilitating multifactorial disorder, characterized by progressive deterioration of cognition and behavior that interferes with the social and professional life of the sufferer. However, the mechanisms of this association are not fully understood. SUMMARY In this review, I discuss recent data that suggest mechanisms of cross-talk between intestinal microbiota dysfunction and the brain that underlie the development of dementia. Potential therapeutic options for dementia are also discussed. The pleiotropic signaling of the metabolic products of the intestinal microbiota together with their specific roles in the maintenance of both the intestinal and blood-brain barriers as well as regulation of local, distant, and circulating immunocytes, and enteric, visceral, and central neural functions are integral to a healthy gut and brain. KEY MESSAGES Research investigating the effect of intestinal microbiota dysfunctions on brain health should focus on multiple interrelated systems involving local and central neuroendocrine, immunocyte, and neural signaling of microbial products and transmitters and neurohumoral cells that not only maintain intestinal, but also blood brain-barrier integrity. The change in intestinal microbiome/dysbiome repertoire is crucial to the development of dementia.
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Affiliation(s)
- Menizibeya O. Welcome
- Department of Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Nile University of Nigeria, Abuja, Nigeria
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