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Jibril TI, Alzoubi KH, Mhaidat NM, Khabour OF, Alqudah MA, Rababa’h AM, Alrabadi N, Al-udatt D. Sildenafil prevents chronic psychosocial stress-induced working memory impairment: Role of brain-derived neurotrophic factor. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2024; 6:100182. [PMID: 38706525 PMCID: PMC11067328 DOI: 10.1016/j.crphar.2024.100182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/29/2024] [Accepted: 04/12/2024] [Indexed: 05/07/2024] Open
Abstract
Background Psychosocial stress, a common feature in modern societies, impairs cognitive functions. It is suggested that stress hormones and elevated excitatory amino acids during stress are responsible for stress-induced cognitive deficits. Reduced brain-derived neurotrophic factor (BDNF) levels, increased oxidative stress, and alteration of synaptic plasticity biomarkers are also possible contributors to the negative impact of stress on learning and memory. Sildenafil citrate is a selective phosphodiesterase type 5 (PDE5) inhibitor and the first oral therapy for the treatment of erectile dysfunction. It has been shown that sildenafil improves learning and memory and possesses antioxidant properties. We hypothesized that administering sildenafil to stressed rats prevents the cognitive deficit induced by chronic psychosocial stress. Methods Psychosocial stress was generated using the intruder model. Sildenafil 3 mg/kg/day was administered intraperitoneally to animals. Behavioral studies were conducted to test spatial learning and memory using the radial arm water maze. Then, the hippocampal BDNF level and several antioxidant markers were assessed. Results This study revealed that chronic psychosocial stress impaired short-term but not long-term memory. The administration of sildenafil prevented this short-term memory impairment. Chronic psychosocial stress markedly reduced the level of hippocampal BDNF (P˂0.05), and this reduction in BDNF was normalized by sildenafil treatment. In addition, neither chronic psychosocial stress nor sildenafil significantly altered the activity of measured oxidative parameters (P > 0.05). Conclusion Chronic psychosocial stress induces short-term memory impairment. The administration of sildenafil citrate prevented this impairment, possibly by normalizing the level of BDNF.
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Affiliation(s)
- Tareq I. Jibril
- Department of Clinical Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Karem H. Alzoubi
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates
- Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Nizar M. Mhaidat
- Department of Clinical Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Omar F. Khabour
- Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Mohammad A.Y. Alqudah
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates
- Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Abeer M. Rababa’h
- Department of Clinical Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Nasr Alrabadi
- Department of Pharmacology, Faculty of Medicine, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Doaa Al-udatt
- Department of Physiology and Biochemistry, Faculty of Medicine, Jordan University of Science and Technology, Irbid, 22110, Jordan
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Sose PM, Kale PP, Doshi GM. Deciphering the Role of Peroxisome Proliferator-activated Receptor α and Phosphodiesterase Type 5 Targets in Alzheimer's Disease. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2024; 23:956-970. [PMID: 37670711 DOI: 10.2174/1871527323666230904150841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 07/05/2023] [Accepted: 07/20/2023] [Indexed: 09/07/2023]
Abstract
The most prevalent cause of dementia is Alzheimer's disease (AD). Although the global AD rate is on a constant rise, medical research is yet to find a cure for this neurological condition. Current available therapeutic drugs for AD treatment only provide symptomatic alleviation. Therefore, it is essential to establish effective AD treatment strategies in addressing clinical needs. The development of disease-modifying treatments for use in the disease's early stages and the advancement of symptomatic drugs principally used in the disease's later stages are priorities in AD research. Given that the etiology of AD is difficult to comprehend, using a multimodal therapy intervention that targets molecular targets of AD-related degenerative processes is a practical strategy to change the course of AD progression. The current review article discussed PPAR-α (Peroxisome proliferator-activated receptor-α) and PDE5 (Phosphodiesterase type 5) targets with evidence for their preclinical and clinical importance. Furthermore, we support the targets with AD-related processes, functions, and remedial measures. A unique synergistic method for treating AD may involve the beneficial combinatorial targeting of these two receptors. Furthermore, we reviewed different PDE chemical families in this research and identified PDE5 inhibitors as one of the promising AD-related experimental and clinical disease-modifying medications. Lastly, we suggest jointly targeting these two pathways would be more beneficial than monotherapy in AD treatments.
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Affiliation(s)
- Parnika M Sose
- Department of Pharmacology, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, V.M. Road, Vile Parle West, Mumbai-400056, India
| | - Pravin P Kale
- Department of Pharmacology, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, V.M. Road, Vile Parle West, Mumbai-400056, India
| | - Gaurav M Doshi
- Department of Pharmacology, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, V.M. Road, Vile Parle West, Mumbai-400056, India
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Gohel D, Zhang P, Gupta AK, Li Y, Chiang CW, Li L, Hou Y, Pieper AA, Cummings J, Cheng F. Sildenafil as a Candidate Drug for Alzheimer's Disease: Real-World Patient Data Observation and Mechanistic Observations from Patient-Induced Pluripotent Stem Cell-Derived Neurons. J Alzheimers Dis 2024; 98:643-657. [PMID: 38427489 PMCID: PMC10977448 DOI: 10.3233/jad-231391] [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] [Accepted: 01/18/2024] [Indexed: 03/03/2024]
Abstract
Background Alzheimer's disease (AD) is a chronic neurodegenerative disease needing effective therapeutics urgently. Sildenafil, one of the approved phosphodiesterase-5 inhibitors, has been implicated as having potential effect in AD. Objective To investigate the potential therapeutic benefit of sildenafil on AD. Methods We performed real-world patient data analysis using the MarketScan® Medicare Supplemental and the Clinformatics® databases. We conducted propensity score-stratified analyses after adjusting confounding factors (i.e., sex, age, race, and comorbidities). We used both familial and sporadic AD patient induced pluripotent stem cells (iPSC) derived neurons to evaluate the sildenafil's mechanism-of-action. Results We showed that sildenafil usage is associated with reduced likelihood of AD across four new drug compactor cohorts, including bumetanide, furosemide, spironolactone, and nifedipine. For instance, sildenafil usage is associated with a 54% reduced incidence of AD in MarketScan® (hazard ratio [HR] = 0.46, 95% CI 0.32- 0.66) and a 30% reduced prevalence of AD in Clinformatics® (HR = 0.70, 95% CI 0.49- 1.00) compared to spironolactone. We found that sildenafil treatment reduced tau hyperphosphorylation (pTau181 and pTau205) in a dose-dependent manner in both familial and sporadic AD patient iPSC-derived neurons. RNA-sequencing data analysis of sildenafil-treated AD patient iPSC-derived neurons reveals that sildenafil specifically target AD related genes and pathobiological pathways, mechanistically supporting the beneficial effect of sildenafil in AD. Conclusions These real-world patient data validation and mechanistic observations from patient iPSC-derived neurons further suggested that sildenafil is a potential repurposable drug for AD. Yet, randomized clinical trials are warranted to validate the causal treatment effects of sildenafil in AD.
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Affiliation(s)
- Dhruv Gohel
- Genomic Medicine Institute,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Pengyue Zhang
- Department of Biostatistics and Health Data Science, Indiana University, Indianapolis, IN, USA
| | - Amit Kumar Gupta
- Genomic Medicine Institute,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Yichen Li
- Genomic Medicine Institute,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Chien-Wei Chiang
- Department of Biomedical Informatics, College of Medicine, Ohio State University, Columbus, OH, USA
| | - Lang Li
- Department of Biomedical Informatics, College of Medicine, Ohio State University, Columbus, OH, USA
| | - Yuan Hou
- Genomic Medicine Institute,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Andrew A. Pieper
- Brain Health Medicines Center, Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Department of Psychiatry, Case Western Reserve University, Cleveland, OH, USA
- Geriatric Psychiatry, GRECC, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA
- Institute for Transformative Molecular Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH, USA
| | - Jeffrey Cummings
- Department of Brain Health, School of Integrated Health Sciences, Chambers-Grundy Center for Transformative Neuroscience, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Feixiong Cheng
- Genomic Medicine Institute,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Cleveland Clinic Genome Center, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
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Henry DS, Pellegrino RG. A case-control study of phosphodiesterase-5 inhibitor use and Alzheimer's disease and related dementias among male and female patients aged 65 years and older supporting the need for a phase III clinical trial. PLoS One 2023; 18:e0292863. [PMID: 37851623 PMCID: PMC10584171 DOI: 10.1371/journal.pone.0292863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 10/02/2023] [Indexed: 10/20/2023] Open
Abstract
BACKGROUND Phosphodiesterase-5 inhibitors (PDE5i) have been evaluated as a novel treatment for Alzheimer's disease and related dementias (ADRD), but two recent cohort studies have offered opposing conclusions. METHODS We performed an unmatched case-control study using electronic medical records from a large healthcare system to evaluate the association of PDE5i use and ADRD in patients ≥65 years old. RESULTS Odds of PDE5i exposure were 64.2%, 55.7%, and 54.0% lower in patients with ADRD than controls among populations with erectile dysfunction, benign prostatic hyperplasia, and pulmonary hypertension, respectively. We observed odds ratios less than unity among males and females and with exposure to the PDE5i sildenafil (Viagra®) and tadalafil (Cialis®). We also evaluated the odds of exposure to two other common treatments for pulmonary hypertension: endothelin receptor antagonists (ERA) and calcium channel blockers (CCB). The odds of ERA exposure were 63.2% lower, but the odds of CCB exposure were 30.7% higher, in patients with ADRD than controls among the population with pulmonary hypertension. CONCLUSIONS Our results reconcile the opposing conclusions from the previous observational studies and support further research into using PDE5i for prevention and treatment of ADRD.
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Affiliation(s)
- David S. Henry
- Baptist Health Center for Clinical Research, Little Rock, Arkansas, United States of America
| | - Richard G. Pellegrino
- Baptist Health Center for Clinical Research, Little Rock, Arkansas, United States of America
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Pauls MMH, Fish J, Binnie LR, Benjamin P, Betteridge S, Clarke B, Dhillon MPK, Ghatala R, Hainsworth FAH, Howe FA, Khan U, Kruuse C, Madigan JB, Moynihan B, Patel B, Pereira AC, Rostrup E, Shtaya ABY, Spilling CA, Trippier S, Williams R, Young R, Barrick TR, Isaacs JD, Hainsworth AH. Testing the cognitive effects of tadalafil. Neuropsychological secondary outcomes from the PASTIS trial. CEREBRAL CIRCULATION - COGNITION AND BEHAVIOR 2023; 5:100187. [PMID: 37811523 PMCID: PMC10550803 DOI: 10.1016/j.cccb.2023.100187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/25/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023]
Abstract
Cerebral small vessel disease (SVD) is a major cause of cognitive impairment in older people. As secondary endpoints in a phase-2 randomised clinical trial, we tested the effects of single administration of a widely-used PDE5 inhibitor, tadalafil, on cognitive performance in older people with SVD. In a double-blinded, placebo-controlled, cross-over trial, participants received tadalafil (20 mg) and placebo on two visits ≥ 7 days apart (randomised to order of treatment). The Montreal Cognitive Assessment (MOCA) was administered at baseline, alongside a measure to estimate optimal intellectual ability (Test of Premorbid Function). Then, before and after treatment, a battery of neuropsychological tests was administered, assessing aspects of attention, information processing speed, working memory and executive function. Sixty-five participants were recruited and 55 completed the protocol (N = 55, age: 66.8 (8.6) years, range 52-87; 15/40 female/male). Median MOCA score was 26 (IQR: 23, 27], range 15-30). No significant treatment effects were seen in any of the neuropsychological tests. There was a trend towards improved performance on Digit Span Forward (treatment effect 0.37, C.I. 0.01, 0.72; P = 0.0521). We did not identify significant treatment effects of single-administration tadalafil on neuropsychological performance in older people with SVD. The trend observed on Digit Span Forward may help to inform future studies. Clinical trial registration http://www.clinicaltrials.gov. Unique identifier: NCT00123456, https://eudract.ema.europa.eu. Unique identifier: 2015-001,235-20NCT00123456.
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Affiliation(s)
- Mathilde MH Pauls
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Jessica Fish
- Neuropsychology, St George's University Hospitals NHS Foundation Trust, London, UK
- School of Health & Wellbeing, University of Glasgow, UK
| | - Lauren R Binnie
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
| | - Philip Benjamin
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
- Neuroradiology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Shai Betteridge
- Neuropsychology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Brian Clarke
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | | | - Rita Ghatala
- South London Stroke Research Network, London, UK
| | | | - Franklyn A Howe
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
| | - Usman Khan
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Christina Kruuse
- Department of Neurology and Neurovascular Research Unit, Herlev Gentofte Hospital, Denmark
| | - Jeremy B Madigan
- Neuroradiology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Barry Moynihan
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
- Department of Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland
| | - Bhavini Patel
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Anthony C Pereira
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Egill Rostrup
- Mental Health Centre, University of Copenhagen, Glostrup, Denmark
| | - Anan BY Shtaya
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
| | - Catherine A Spilling
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
| | | | | | - Robin Young
- Robertson Centre for Biostatistics, University of Glasgow, UK
| | - Thomas R Barrick
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
| | - Jeremy D Isaacs
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Atticus H Hainsworth
- Molecular & Clinical Sciences Research Institute, St George's University of London, UK
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
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6
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ElHady AK, El-Gamil DS, Abdel-Halim M, Abadi AH. Advancements in Phosphodiesterase 5 Inhibitors: Unveiling Present and Future Perspectives. Pharmaceuticals (Basel) 2023; 16:1266. [PMID: 37765073 PMCID: PMC10536424 DOI: 10.3390/ph16091266] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/25/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023] Open
Abstract
Phosphodiesterase 5 (PDE5) inhibitors presented themselves as important players in the nitric oxide/cGMP pathway, thus exerting a profound impact on various physiological and pathological processes. Beyond their well-known efficacy in treating male erectile dysfunction (ED) and pulmonary arterial hypertension (PAH), a plethora of studies have unveiled their significance in the treatment of a myriad of other diseases, including cognitive functions, heart failure, multiple drug resistance in cancer therapy, immune diseases, systemic sclerosis and others. This comprehensive review aims to provide an updated assessment of the crucial role played by PDE5 inhibitors (PDE5-Is) as disease-modifying agents taking their limiting side effects into consideration. From a medicinal chemistry and drug discovery perspective, the published PDE5-Is over the last 10 years and their binding characteristics are systemically discussed, and advancement in properties is exposed. A persistent challenge encountered with these agents lies in their limited isozyme selectivity; considering this obstacle, this review also highlights the breakthrough development of the recently reported PDE5 allosteric inhibitors, which exhibit an unparalleled level of selectivity that was rarely achievable by competitive inhibitors. The implications and potential impact of these novel allosteric inhibitors are meticulously explored. Additionally, the concept of multi-targeted ligands is critically evaluated in relation to PDE5-Is by inspecting the broader spectrum of their molecular interactions and effects. The objective of this review is to provide insight into the design of potent, selective PDE5-Is and an overview of their biological function, limitations, challenges, therapeutic potentials, undergoing clinical trials, future prospects and emerging uses, thus guiding upcoming endeavors in both academia and industry within this domain.
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Affiliation(s)
- Ahmed K. ElHady
- School of Life and Medical Sciences, University of Hertfordshire Hosted by Global Academic Foundation, New Administrative Capital, Cairo 11865, Egypt;
| | - Dalia S. El-Gamil
- Department of Chemistry, Faculty of Pharmacy, Ahram Canadian University, Cairo 12451, Egypt;
| | - Mohammad Abdel-Halim
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt;
| | - Ashraf H. Abadi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt;
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Hainsworth AH, Arancio O, Elahi FM, Isaacs JD, Cheng F. PDE5 inhibitor drugs for use in dementia. ALZHEIMER'S & DEMENTIA (NEW YORK, N. Y.) 2023; 9:e12412. [PMID: 37766832 PMCID: PMC10520293 DOI: 10.1002/trc2.12412] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 07/07/2023] [Accepted: 07/08/2023] [Indexed: 09/29/2023]
Abstract
Alzheimer's disease and related dementias (ADRD) remain a major health-care challenge with few licensed medications. Repurposing existing drugs may afford prevention and treatment. Phosphodiesterase-5 (PDE5) is widely expressed in vascular myocytes, neurons, and glia. Potent, selective, Food and Drug Administration-approved PDE5 inhibitors are already in clinical use (sildenafil, vardenafil, tadalafil) as vasodilators in erectile dysfunction and pulmonary arterial hypertension. Animal data indicate cognitive benefits of PDE5 inhibitors. In humans, real-world patient data suggest that sildenafil and vardenafil are associated with reduced dementia risk. While a recent clinical trial of acute tadalafil on cerebral blood flow was neutral, there may be chronic actions of PDE5 inhibition on cerebrovascular or synaptic function. We provide a perspective on the potential utility of PDE5 inhibitors for ADRD. We conclude that further prospective clinical trials with PDE5 inhibitors are warranted. The choice of drug will depend on brain penetration, tolerability in older people, half-life, and off-target effects. HIGHLIGHTS Potent phosphodiesterase-5 (PDE5) inhibitors are in clinical use as vasodilators.In animals PDE5 inhibitors enhance synaptic function and cognitive ability.In humans the PDE5 inhibitor sildenafil is associated with reduced risk of Alzheimer's disease.Licensed PDE5 inhibitors have potential for repurposing in dementia.Prospective clinical trials of PDE5 inhibitors are warranted.
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Affiliation(s)
- Atticus H. Hainsworth
- Molecular & Clinical Sciences Research InstituteSt George's University of LondonLondonUK
- Department of NeurologySt George's University Hospitals NHS Foundation TrustLondonUK
| | - Ottavio Arancio
- Department of Pathology and Cell BiologyTaub Institute for Research on Alzheimer's Disease and the Aging BrainDepartment of MedicineColumbia UniversityNew YorkNew YorkUSA
| | - Fanny M. Elahi
- Departments of Neurology and NeuroscienceRonald M. Loeb Center for Alzheimer's DiseaseFriedman Brain InstituteIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
| | - Jeremy D. Isaacs
- Molecular & Clinical Sciences Research InstituteSt George's University of LondonLondonUK
- Department of NeurologySt George's University Hospitals NHS Foundation TrustLondonUK
| | - Feixiong Cheng
- Genomic Medicine InstituteLerner Research InstituteCleveland ClinicClevelandOhioUSA
- Department of Molecular MedicineCleveland Clinic Lerner College of MedicineCase Western Reserve UniversityClevelandOhioUSA
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Pilarzyk K, Porcher L, Capell WR, Burbano SD, Davis J, Fisher JL, Gorny N, Petrolle S, Kelly MP. Conserved age-related increases in hippocampal PDE11A4 cause unexpected proteinopathies and cognitive decline of social associative memories. Aging Cell 2022; 21:e13687. [PMID: 36073342 PMCID: PMC9577960 DOI: 10.1111/acel.13687] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/06/2022] [Accepted: 07/22/2022] [Indexed: 01/25/2023] Open
Abstract
In humans, associative memories are more susceptible to age-related cognitive decline (ARCD) than are recognition memories. Reduced cAMP/cGMP signaling in the hippocampus may contribute to ARCD. Here, we found that both aging and traumatic brain injury-associated dementia increased the expression of the cAMP/cGMP-degrading enzyme phosphodiesterase 11A (PDE11A) in the human hippocampus. Further, age-related increases in hippocampal PDE11A4 mRNA and protein were conserved in mice, as was the increased vulnerability of associative versus recognition memories to ARCD. Interestingly, mouse PDE11A4 protein in the aged ventral hippocampus (VHIPP) ectopically accumulated in the membrane fraction and filamentous structures we term "ghost axons." These age-related increases in expression were driven by reduced exoribonuclease-mediated degradation of PDE11A mRNA and increased PDE11A4-pS117/pS124, the latter of which also drove the punctate accumulation of PDE11A4. In contrast, PDE11A4-pS162 caused dispersal. Importantly, preventing age-related increases in PDE11 expression via genetic deletion protected mice from ARCD of short-term and remote long-term associative memory (aLTM) in the social transmission of food preference assay, albeit at the expense of recent aLTM. Further, mimicking age-related overexpression of PDE11A4 in CA1 of old KO mice caused aging-like impairments in CREB function and remote social-but not non-social-LTMs. RNA sequencing and phosphoproteomic analyses of VHIPP identified cGMP-PKG-as opposed to cAMP-PKA-as well as circadian entrainment, glutamatergic/cholinergic synapses, calcium signaling, oxytocin, and retrograde endocannabinoid signaling as mechanisms by which PDE11A deletion protects against ARCD. Together, these data suggest that PDE11A4 proteinopathies acutely impair signaling in the aged brain and contribute to ARCD of social memories.
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Affiliation(s)
- Katy Pilarzyk
- Department of Pharmacology, Physiology & NeuroscienceUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
| | - Latarsha Porcher
- Department of Pharmacology, Physiology & NeuroscienceUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
| | - William R. Capell
- Department of Pharmacology, Physiology & NeuroscienceUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
| | - Steven D. Burbano
- Department of Pharmacology, Physiology & NeuroscienceUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
| | - Jeff Davis
- Instrument Resource FacilityUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
| | - Janet L. Fisher
- Department of Pharmacology, Physiology & NeuroscienceUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
| | - Nicole Gorny
- Department of Anatomy & NeurobiologyUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Siena Petrolle
- Department of Anatomy & NeurobiologyUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Michy P. Kelly
- Department of Pharmacology, Physiology & NeuroscienceUniversity of South Carolina School of MedicineColumbiaSouth CarolinaUSA
- Department of Anatomy & NeurobiologyUniversity of Maryland School of MedicineBaltimoreMarylandUSA
- Center for Research on AgingUniversity of Maryland School of MedicineBaltimoreMarylandUSA
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Li F, Zhou SN, Zeng X, Li Z, Yang R, Wang XX, Meng B, Pei WL, Lu L. Activation of the TREK-1 Potassium Channel Improved Cognitive Deficits in a Mouse Model of Alzheimer's Disease by Modulating Glutamate Metabolism. Mol Neurobiol 2022; 59:5193-5206. [PMID: 35678977 DOI: 10.1007/s12035-022-02776-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 02/10/2022] [Indexed: 10/18/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive dysfunction. The glutamate (Glu) metabolic pathway may be a major contributor to the memory dysfunction associated with AD. The TWIK-related potassium channel-1 (TREK-1) protects against brain ischemia, but any specific role for the channel in AD remains unknown. In this study, we used SAMP8 mice as an AD model and age-matched SAMR1 mice as controls. We explored the trends of changes in TREK-1 channel activity and the levels of AD-related molecules in the brains of SAMP8 mice. We found that the expression level of TREK-1 increased before 3 months of age and then began to decline. The levels of Tau and Glu increased with age whereas the acetylcholine level decreased with age. α-Linolenic acid (ALA), an activator of the TREK-1 channel, significantly increased the TREK-1 level, and improved the learning and memory deficits of SAMP8 mice aged 6 months. The mechanism in play may involve the Glu metabolic pathway. After activation of the TREK-1 channel, damaged neurons and astrocytes were rescued, the levels of Glu and the N-methyl-D-aspartate receptor were downregulated, and the level of glutamate transporter-1 was upregulated. These findings suggest that TREK-1 plays a crucial role in the pathological progression of AD; activation of the TREK-1 channel improved cognitive deficits in SAMP8 mice via a mechanism that involved Glu metabolism. The TREK-1 potassium channel may thus be a valuable therapeutic target in AD patients.
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Affiliation(s)
- Fang Li
- School of Basic Medical Sciences, Lanzhou University, Lanzhou, 73000, Gansu, China
| | - Shu-Ning Zhou
- School of Basic Medical Sciences, Lanzhou University, Lanzhou, 73000, Gansu, China.,The College of Traditional Chinese Medicine, Zhejiang Pharmaceutical College, Ningbo, 315000, Zhejiang, China
| | - Xin Zeng
- School of Basic Medical Sciences, Lanzhou University, Lanzhou, 73000, Gansu, China
| | - Zhen Li
- School of Basic Medical Sciences, Lanzhou University, Lanzhou, 73000, Gansu, China
| | - Rui Yang
- The Endocrinology Department, Lanzhou Hospital of Traditional Chinese Medicine, Lanzhou, 73000, Gansu, China.
| | - Xue-Xi Wang
- School of Basic Medical Sciences, Lanzhou University, Lanzhou, 73000, Gansu, China
| | - Bin Meng
- The Second Clinical Medical College, Lanzhou University, Lanzhou, 73000, Gansu, China
| | - Wei-Lin Pei
- The Second Clinical Medical College, Lanzhou University, Lanzhou, 73000, Gansu, China
| | - Li Lu
- School of Basic Medical Sciences, Lanzhou University, Lanzhou, 73000, Gansu, China.
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Lazic A, Balint V, Stanisavljevic Ninkovic D, Peric M, Stevanovic M. Reactive and Senescent Astroglial Phenotypes as Hallmarks of Brain Pathologies. Int J Mol Sci 2022; 23:ijms23094995. [PMID: 35563385 PMCID: PMC9100382 DOI: 10.3390/ijms23094995] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/23/2022] [Accepted: 04/27/2022] [Indexed: 02/06/2023] Open
Abstract
Astrocytes, as the most abundant glial cells in the central nervous system, are tightly integrated into neural networks and participate in numerous aspects of brain physiology and pathology. They are the main homeostatic cells in the central nervous system, and the loss of astrocyte physiological functions and/or gain of pro-inflammatory functions, due to their reactivation or cellular senescence, can have profound impacts on the surrounding microenvironment with pathological outcomes. Although the importance of astrocytes is generally recognized, and both senescence and reactive astrogliosis have been extensively reviewed independently, there are only a few comparative overviews of these complex processes. In this review, we summarize the latest data regarding astrocyte reactivation and senescence, and outline similarities and differences between these phenotypes from morphological, functional, and molecular points of view. A special focus has been given to neurodegenerative diseases, where these phenotypic alternations of astrocytes are significantly implicated. We also summarize current perspectives regarding new advances in model systems based on astrocytes as well as data pointing to these glial cells as potential therapeutic targets.
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Affiliation(s)
- Andrijana Lazic
- Laboratory for Human Molecular Genetics, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia; (V.B.); (D.S.N.); (M.P.); (M.S.)
- Correspondence:
| | - Vanda Balint
- Laboratory for Human Molecular Genetics, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia; (V.B.); (D.S.N.); (M.P.); (M.S.)
| | - Danijela Stanisavljevic Ninkovic
- Laboratory for Human Molecular Genetics, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia; (V.B.); (D.S.N.); (M.P.); (M.S.)
| | - Mina Peric
- Laboratory for Human Molecular Genetics, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia; (V.B.); (D.S.N.); (M.P.); (M.S.)
| | - Milena Stevanovic
- Laboratory for Human Molecular Genetics, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia; (V.B.); (D.S.N.); (M.P.); (M.S.)
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia
- Serbian Academy of Sciences and Arts, Kneza Mihaila 35, 11001 Belgrade, Serbia
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Xi M, Sun T, Chai S, Xie M, Chen S, Deng L, Du K, Shen R, Sun H. Therapeutic potential of phosphodiesterase inhibitors for cognitive amelioration in Alzheimer's disease. Eur J Med Chem 2022; 232:114170. [DOI: 10.1016/j.ejmech.2022.114170] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/27/2022] [Accepted: 01/30/2022] [Indexed: 02/07/2023]
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12
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Taoro-González L, Cabrera-Pastor A, Sancho-Alonso M, Felipo V. Intracellular and extracelluar cyclic GMP in the brain and the hippocampus. VITAMINS AND HORMONES 2022; 118:247-288. [PMID: 35180929 DOI: 10.1016/bs.vh.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cyclic Guanosine-Monophosphate (cGMP) is implicated as second messenger in a plethora of pathways and its effects are executed mainly by cGMP-dependent protein kinases (PKG). It is involved in both peripheral (cardiovascular regulation, intestinal secretion, phototransduction, etc.) and brain (hippocampal synaptic plasticity, neuroinflammation, cognitive function, etc.) processes. Stimulation of hippocampal cGMP signaling have been proved to be beneficial in animal models of aging, Alzheimer's disease or hepatic encephalopathy, restoring different cognitive functions such as passive avoidance, object recognition or spatial memory. However, even when some inhibitors of cGMP-degrading enzymes (PDEs) are already used against peripheral pathologies, their utility as neurological treatments is still under clinical investigation. Additionally, it has been demonstrated a list of cGMP roles as not second but first messenger. The role of extracellular cGMP has been specially studied in hippocampal function and cognitive impairment in animal models and it has emerged as an important modulator of neuroinflammation-mediated cognitive alterations and hippocampal synaptic plasticity malfunction. Specifically, it has been demonstrated that extracellular cGMP decreases hippocampal IL-1β levels restoring membrane expression of glutamate receptors in the hippocampus and cognitive function in hyperammonemic rats. The mechanisms implicated are still unclear and might involve complex interactions between hippocampal neurons, astrocytes and microglia. Membrane targets for extracellular cGMP are still poorly understood and must be addressed in future studies.
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Affiliation(s)
- Lucas Taoro-González
- Department of Clinical Psychology, Psychobiology and Methodology, Area of Psycobiology, University of La Laguna, Tenerife, Spain
| | - Andrea Cabrera-Pastor
- Fundación Investigación Hospital Clínico, Instituto de Investigación Sanitaria (INCLIVA), Valencia, Spain; Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - María Sancho-Alonso
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Vicente Felipo
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain.
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Abstract
Substantial evidence, composed of drug mechanisms of action, in vivo testing, and epidemiological data, exists to support clinical testing of FDA-approved drugs for repurposing to the treatment of Alzheimer’s disease (AD). Licensed compound investigation can often proceed at a faster and more cost-effective manner than un-approved compounds moving through the drug pipeline. As the prevalence of AD increases with life expectancy, the current rise in life expectancy amalgamated with the lack of an effective drug for the treatment of AD unnecessarily burdens our medical system and is an urgent public health concern. The unfounded reluctance to examine repurposing existing drugs for possible AD therapy further impedes the possibility of improving the quality of patient lives with a terminal disease. This review summarizes some evidence which exists to suggest certain already-approved drugs may be considered for the treatment of AD and will perhaps encourage physicians to off-label prescribe these safe therapeutics.
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14
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Targeting impaired nutrient sensing with repurposed therapeutics to prevent or treat age-related cognitive decline and dementia: A systematic review. Ageing Res Rev 2021; 67:101302. [PMID: 33609776 DOI: 10.1016/j.arr.2021.101302] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 02/13/2021] [Accepted: 02/15/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND Dementia is a debilitating syndrome that significantly impacts individuals over the age of 65 years. There are currently no disease-modifying treatments for dementia. Impairment of nutrient sensing pathways has been implicated in the pathogenesis of dementia, and may offer a novel treatment approach for dementia. AIMS This systematic review collates all available evidence for Food and Drug Administration (FDA)-approved therapeutics that modify nutrient sensing in the context of preventing cognitive decline or improving cognition in ageing, mild cognitive impairment (MCI), and dementia populations. METHODS PubMed, Embase and Web of Science databases were searched using key search terms focusing on available therapeutics such as 'metformin', 'GLP1', 'insulin' and the dementias including 'Alzheimer's disease' and 'Parkinson's disease'. Articles were screened using Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia). The risk of bias was assessed using the Cochrane Risk of Bias tool v 2.0 for human studies and SYRCLE's risk of bias tool for animal studies. RESULTS Out of 2619 articles, 114 were included describing 31 different 'modulation of nutrient sensing pathway' therapeutics, 13 of which specifically were utilized in human interventional trials for normal ageing or dementia. Growth hormone secretagogues improved cognitive outcomes in human mild cognitive impairment, and potentially normal ageing populations. In animals, all investigated therapeutic classes exhibited some cognitive benefits in dementia models. While the risk of bias was relatively low in human studies, this risk in animal studies was largely unclear. CONCLUSIONS Modulation of nutrient sensing pathway therapeutics, particularly growth hormone secretagogues, have the potential to improve cognitive outcomes. Overall, there is a clear lack of translation from animal models to human populations.
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15
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Ungerleider K, Beck J, Lissa D, Turnquist C, Horikawa I, Harris BT, Harris CC. Astrocyte senescence and SASP in neurodegeneration: tau joins the loop. Cell Cycle 2021; 20:752-764. [PMID: 33818291 DOI: 10.1080/15384101.2021.1909260] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Tau accumulation is a core component of Alzheimer's disease and other neurodegenerative tauopathies. While tau's impact on neurons is a major area of research, the effect of extracellular tau on astrocytes is largely unknown. This article summarizes our recent studies showing that astrocyte senescence plays a critical role in neurodegenerative diseases and integrates extracellular tau into the regulatory loop of senescent astrocyte-mediated neurotoxicity. Human astrocytes in vitro undergoing senescence were shown to acquire the inflammatory senescence-associated secretory phenotype (SASP) and toxicity to neurons, which may recapitulate aging- and disease-associated neurodegeneration. Here, we show that human astrocytes exposed to extracellular tau in vitro also undergo cellular senescence and acquire a neurotoxic SASP (e.g. IL-6 secretion), with oxidative stress response (indicated by upregulated NRF2 target genes) and a possible activation of inflammasome (indicated by upregulated ASC and IL-1β). These findings suggest that senescent astrocytes induced by various conditions and insults, including tau exposure, may represent a therapeutic target to inhibit or delay the progression of neurodegenerative diseases. We also discuss the pathological activity of extracellular tau in microglia and astrocytes, the disease relevance and diversity of tau forms, therapeutics targeting senescence in neurodegeneration, and the roles of p53 and its isoforms in astrocyte-mediated neurotoxicity and neuroprotection.
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Affiliation(s)
- Kyra Ungerleider
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jessica Beck
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Department of Comparative Pathobiology, Purdue University, West Layfette, Indiana, USA
| | - Delphine Lissa
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Casmir Turnquist
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,University of Oxford Medical School, John Radcliffe Hospital, Oxford, UK
| | - Izumi Horikawa
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Brent T Harris
- Department of Neurology, Georgetown University Medical Center, Washington, DC, USA
| | - Curtis C Harris
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Lapatinib ditosylate rescues memory impairment in D-galactose/ovariectomized rats: Potential repositioning of an anti-cancer drug for the treatment of Alzheimer's disease. Exp Neurol 2021; 341:113697. [PMID: 33727095 DOI: 10.1016/j.expneurol.2021.113697] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 02/08/2021] [Accepted: 03/11/2021] [Indexed: 12/16/2022]
Abstract
Epidermal growth factor receptor (EGFR) signaling plays a substantial role in learning and memory. The upregulation of EGFR has been embroiled in the pathophysiology of Alzheimer's disease (AD). Nevertheless, most of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have been extensively studied for non-CNS diseases such as cancer and rheumatoid arthritis. TKIs targeting-based research in neurodegenerative disorders sounds to be lagging behind those of other diseases. Hence, this study aims to explore the molecular signaling pathways and the efficacy of treatment with lapatinib ditosylate (LAP), as one of EGFR-TKIs that has not yet been investigated in AD, on cognitive decline induced by ovariectomy (OVX) with chronic administration of D-galactose (D-gal) in female Wistar albino rats. OVX rats were injected with 150 mg/kg/day D-gal ip for 8 weeks to induce AD. Administration of 100 mg/kg/day LAP p.o. for 3 weeks starting after the 8th week of D-gal administration improved memory and debilitated histopathological alterations. LAP decreased the expression of GFAP, p-tau, and Aβ 1-42. Besides, it reduced EGFR, HER-2, TNF-α, NOX-1, GluR-II, p38 MAPK, and p-mTOR. LAP increased nitrite, and neuronal pro-survival transduction proteins; p-PI3K, p-AKT, and p-GSK-3β levels. Taken together, these findings suggest the role of LAP in ameliorating D-gal-induced AD in OVX rats via activating the pro-survival pathway; PI3K-Akt-GSK-3β, while inhibiting p-mTOR, NOX-1, and p38 MAPK pathways. Moreover, this research offered a significant opportunity to advance awareness of the repositioning of TKI anti-cancer drugs for the treatment of AD.
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17
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Gorny N, Kelly MP. Alterations in cyclic nucleotide signaling are implicated in healthy aging and age-related pathologies of the brain. VITAMINS AND HORMONES 2021; 115:265-316. [PMID: 33706951 DOI: 10.1016/bs.vh.2020.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It is not only important to consider how hormones may change with age, but also how downstream signaling pathways that couple to hormone receptors may change. Among these hormone-coupled signaling pathways are the 3',5'-cyclic guanosine monophosphate (cGMP) and 3',5'-cyclic adenosine monophosphate (cAMP) intracellular second messenger cascades. Here, we test the hypothesis that dysfunction of cAMP and/or cGMP synthesis, execution, and/or degradation occurs in the brain during healthy and pathological diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. Although most studies report lower cyclic nucleotide signaling in the aged brain, with further reductions noted in the context of age-related diseases, there are select examples where cAMP signaling may be elevated in select tissues. Thus, therapeutics would need to target cAMP/cGMP in a tissue-specific manner if efficacy for select symptoms is to be achieved without worsening others.
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Affiliation(s)
- Nicole Gorny
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Michy P Kelly
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States.
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18
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Montalto G, Caudano F, Sturla L, Bruzzone S, Salis A, Damonte G, Prickaerts J, Fedele E, Ricciarelli R. Protein kinase G phosphorylates the Alzheimer's disease-associated tau protein at distinct Ser/Thr sites. Biofactors 2021; 47:126-134. [PMID: 33469985 DOI: 10.1002/biof.1705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 11/10/2022]
Abstract
Intraneuronal accumulation of hyperphosphorylated tau is a pathological hallmark of several neurodegenerative disorders, including Alzheimer's disease. Phosphorylation plays a crucial role in modulating the tau-microtubule interaction and the ability of the protein to aggregate, but despite efforts during the past decades, the real identity of the kynases involved in vivo remains uncertain. Here, for the first time, we demonstrate that the cGMP-dependent protein kinase G (PKG) phosphorylates tau in both in vitro and in vivo models. More intriguingly, we provide evidence that PKG phosphorylates tau at Ser214 but not at Ser202, a condition that could reduce the pathological aggregation of the protein shifting tau from a pro-aggregant to a neuroprotective anti-aggregant conformation.
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Affiliation(s)
- Giulia Montalto
- Section of General Pathology, Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Francesca Caudano
- Section of General Pathology, Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Laura Sturla
- Section of Biochemistry, Department of Experimental Medicine, Center for Excellence in Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Santina Bruzzone
- Section of Biochemistry, Department of Experimental Medicine, Center for Excellence in Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Annalisa Salis
- Section of Biochemistry, Department of Experimental Medicine, Center for Excellence in Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Gianluca Damonte
- Section of Biochemistry, Department of Experimental Medicine, Center for Excellence in Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Jos Prickaerts
- Department of Psychiatric and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Ernesto Fedele
- Section of Pharmacology and Toxicology, Department of Pharmacy, University of Genoa, Genoa, Italy
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Roberta Ricciarelli
- Section of General Pathology, Department of Experimental Medicine, University of Genoa, Genoa, Italy
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy
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Ribaudo G, Ongaro A, Zagotto G, Memo M, Gianoncelli A. Therapeutic Potential of Phosphodiesterase Inhibitors against Neurodegeneration: The Perspective of the Medicinal Chemist. ACS Chem Neurosci 2020; 11:1726-1739. [PMID: 32401481 PMCID: PMC8007108 DOI: 10.1021/acschemneuro.0c00244] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
![]()
Increasing human
life expectancy prompts the development of novel
remedies for cognitive decline: 44 million people worldwide are affected
by dementia, and this number is predicted to triple by 2050. Acetylcholinesterase
and N-methyl-d-aspartate receptors represent
the targets of currently available drugs for Alzheimer’s disease,
which are characterized by limited efficacy. Thus, the search for
therapeutic agents with alternative or combined mechanisms of action
is wide open. Since variations in 3′,5′-cyclic adenosine
monophosphate, 3′,5′-cyclic guanosine monophosphate,
and/or nitric oxide levels interfere with downstream pathways involved
in memory processes, evidence supporting the potential of phosphodiesterase
(PDE) inhibitors in contrasting neurodegeneration should be
critically considered. For the preparation of this Review, more than
140 scientific papers were retrieved by searching PubMed and Scopus
databases. A systematic approach was adopted when overviewing the
different PDE isoforms, taking into account details on brain localization,
downstream molecular mechanisms, and inhibitors currently under study,
according to available in vitro and in vivo data. In the context of drug repurposing, a section focusing on
PDE5 was introduced. Original computational studies were performed
to rationalize the emerging evidence that suggests the role of PDE5
inhibitors as multi-target agents against neurodegeneration.
Moreover, since such compounds must cross the blood–brain barrier
and reach inhibitory concentrations in the central nervous system
to exert their therapeutic activity, physicochemical parameters
were analyzed and discussed. Taken together, literature and computational
data suggest that some PDE5 inhibitors, such as tadalafil, represent
promising candidates.
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Affiliation(s)
- Giovanni Ribaudo
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Alberto Ongaro
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Giuseppe Zagotto
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy
| | - Maurizio Memo
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Alessandra Gianoncelli
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
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Duarte-Silva E, Filho AJMC, Barichello T, Quevedo J, Macedo D, Peixoto C. Phosphodiesterase-5 inhibitors: Shedding new light on the darkness of depression? J Affect Disord 2020; 264:138-149. [PMID: 32056743 DOI: 10.1016/j.jad.2019.11.114] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/22/2019] [Accepted: 11/26/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Phosphodiesterase-5 inhibitors (PDE5Is) are used to treat erectile dysfunction (ED). Recently, the antidepressant-like effect of PDE5Is was demonstrated in animal models of depression. In clinical settings, PDE5Is were studied only for ED associated depression. Hence, there are no studies evaluating the effects of PDE5Is for the treatment of major depressive disorder (MDD) without ED. In this review article, we aimed to discuss the use of PDE5Is in the context of MDD, highlighting the roles of PDE genes in the development of MDD, the potential mechanisms by which PDE5Is can be beneficial for MDD and the potentials and limitations of PDE5Is repurposing to treat MDD. METHODS We used PubMed (MEDLINE) database to collect the studies cited in this review. Papers written in English language regardless the year of publication were selected. RESULTS A few preclinical studies support the antidepressant-like activity of PDE5Is. Clinical studies in men with ED and depression suggest that PDE5Is improve depressive symptoms. No clinical studies were conducted in subjects suffering from depression without ED. Antidepressant effect of PDE5Is may be explained by multiple mechanisms including inhibition of brain inflammation and modulation of neuroplasticity. LIMITATIONS The low number of preclinical and absence of clinical studies to support the antidepressant effect of PDE5Is. CONCLUSIONS No clinical trial was conducted to date evaluating PDE5Is in depressed patients without ED. PDE5Is' anti-inflammatory and neuroplasticity mechanisms may justify the potential antidepressant effect of these drugs. Despite this, clinical trials evaluating their efficacy in depressed patients need to be conducted.
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Affiliation(s)
- Eduardo Duarte-Silva
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Oswaldo Cruz Foundation (FIOCRUZ-PE), Recife, PE, Brazil; Graduate Program in Biosciences and Biotechnology for Health (PPGBBS), Aggeu Magalhães Institute (IAM), Recife, PE, Brazil.
| | - Adriano José Maia Chaves Filho
- Neuropsychopharmacology Laboratory, Drug Research and Development Center, Faculty of Medicine, Universidade Federal do Ceará, Fortaleza, CE, Brazil
| | - Tatiana Barichello
- Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, 1941 East Road, Houston, TX 77054, United States; Laboratory of Neurosciences, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina-UNESC, Criciúma, SC, Brazil; Center of Excellence on Mood Disorders, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States.
| | - João Quevedo
- Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, 1941 East Road, Houston, TX 77054, United States; Laboratory of Neurosciences, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina-UNESC, Criciúma, SC, Brazil; Center of Excellence on Mood Disorders, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States.
| | - Danielle Macedo
- Neuropsychopharmacology Laboratory, Drug Research and Development Center, Faculty of Medicine, Universidade Federal do Ceará, Fortaleza, CE, Brazil; Department of Physiology and Pharmacology, Faculty of Medicine, Universidade Federal do Ceará, Fortaleza, CE, Brazil; National Institute for Translational Medicine (INCT-TM, CNPq), Ribeirão Preto, Brazil
| | - Christina Peixoto
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Oswaldo Cruz Foundation (FIOCRUZ-PE), Recife, PE, Brazil; National Institute of Science and Technology on Neuroimmunomodulation (INCT-NIM), Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
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21
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Early sirtuin 2 inhibition prevents age-related cognitive decline in a senescence-accelerated mouse model. Neuropsychopharmacology 2020; 45:347-357. [PMID: 31471557 PMCID: PMC6901465 DOI: 10.1038/s41386-019-0503-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 08/02/2019] [Accepted: 08/22/2019] [Indexed: 02/07/2023]
Abstract
The senescence-accelerated mouse prone-8 (SAMP8) model has been considered as a good model for aged-related cognitive decline and Alzheimer's disease (AD). Since epigenetic alterations represent a crucial mechanism during aging, in the present study we tested whether the inhibition of the histone deacetylase sirtuin 2 (SIRT2) could ameliorate the age-dependent cognitive impairments and associated neuropathology shown by SAMP8 mice. To this end, the potent SIRT2-selective inhibitor, 33i (5 mg/kg i.p. 8 weeks) was administered to 5-month-old (early treatment) and 8-month-old (late treatment) SAMP8 and aged matched control, senescence-accelerated mouse resistant-1 (SAMR1) mice. 33i administration to 5-month-old SAMP8 mice improved spatial learning and memory impairments shown by this strain in the Morris water maze. SAMP8 showed hyperphosphorylation of tau protein and decrease levels of SIRT1 in the hippocampus, which were not altered by 33i treatment. However, this treatment upregulated the glutamate receptor subunits GluN2A, GluN2B, and GluA1 in both SAMR1 and SAMP8. Moreover, early SIRT2 inhibition prevented neuroinflammation evidenced by reduced levels of GFAP, IL-1β, Il-6, and Tnf-α, providing a plausible explanation for the improvement of cognitive deficits shown by 33i-treated SAMP8 mice. When 33i was administered to 8-month-old SAMP8 with a severe established pathology, increases in GluN2A, GluN2B, and GluA1 were observed; however, it was not able to reverse the cognitive decline or the neuroinflammation. These results suggest that early SIRT2 inhibition might be beneficial in preventing age-related cognitive deficits, neuroinflammation, and AD progression and could be an emerging candidate for the treatment of other diseases linked to dementia.
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22
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Zhu L, Zhang Z, Hou XJ, Wang YF, Yang JY, Wu CF. Inhibition of PDE5 attenuates streptozotocin-induced neuroinflammation and tau hyperphosphorylation in a streptozotocin-treated rat model. Brain Res 2019; 1722:146344. [DOI: 10.1016/j.brainres.2019.146344] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 06/10/2019] [Accepted: 07/20/2019] [Indexed: 01/10/2023]
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23
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El-Bakly W, Wagdy O, Sobhy A, abo elenain O, Riad MS, El Sayed M, Tarkhan S, Yassen M, Mahmoud A, Bassiony M, Nabil N. The efficacy and underlying mechanism of phosphodiesterase- 5 inhibitors in preventing cognitive impairment and Alzheimer pathology: A systematic review of animal studies. Behav Brain Res 2019; 372:112004. [DOI: 10.1016/j.bbr.2019.112004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 12/13/2022]
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24
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Liu L, Xu H, Ding S, Wang D, Song G, Huang X. Phosphodiesterase 5 inhibitors as novel agents for the treatment of Alzheimer's disease. Brain Res Bull 2019; 153:223-231. [PMID: 31493542 DOI: 10.1016/j.brainresbull.2019.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/18/2019] [Accepted: 09/01/2019] [Indexed: 01/21/2023]
Abstract
Alzheimer's disease (AD), characterized by a progressive impairment of memory and cognition, is a major health problem in both developing and developed countries. Currently, no drugs can reverse the progression of AD. Phosphodiesterase 5 (PDE5) is a critical component of the cyclic guanosine monophosphate/protein kinase G (cGMP/PKG) signaling pathway in neurons, the inhibition of which has produced neuroprotective effects, and PDE5 inhibitors have recently been thought to be potential therapeutic agents for AD. In this paper, we summarized the outstanding progress that has been made in PDE5 inhibitors as anti-AD agents with encouraging results in animal studies, clinical trials and the investigations on the underlying mechanisms. The novel PDE5 inhibitors reported recently in the treatment of AD were also reviewed and discussed.
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Affiliation(s)
- Li Liu
- School of Pharmaceutical Engineering & Life Science, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Huang Xu
- School of Pharmaceutical Engineering & Life Science, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Shumin Ding
- School of Pharmaceutical Engineering & Life Science, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Dongyan Wang
- Department of Medicine, Yangzhou Polytechnic College, Yangzhou, Jiangsu 225009, China
| | - Guoqiang Song
- School of Pharmaceutical Engineering & Life Science, Changzhou University, Changzhou, Jiangsu 213164, China.
| | - Xianfeng Huang
- School of Pharmaceutical Engineering & Life Science, Changzhou University, Changzhou, Jiangsu 213164, China.
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Griñán-Ferré C, Corpas R, Puigoriol-Illamola D, Palomera-Ávalos V, Sanfeliu C, Pallàs M. Understanding Epigenetics in the Neurodegeneration of Alzheimer's Disease: SAMP8 Mouse Model. J Alzheimers Dis 2019; 62:943-963. [PMID: 29562529 PMCID: PMC5870033 DOI: 10.3233/jad-170664] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Epigenetics is emerging as the missing link among genetic inheritance, environmental influences, and body and brain health status. In the brain, specific changes in nucleic acids or their associated proteins in neurons and glial cells might imprint differential patterns of gene activation that will favor either cognitive enhancement or cognitive loss for more than one generation. Furthermore, derangement of age-related epigenetic signaling is appearing as a significant risk factor for illnesses of aging, including neurodegeneration and Alzheimer’s disease (AD). In addition, better knowledge of epigenetic mechanisms might provide hints and clues in the triggering and progression of AD. Intense research in experimental models suggests that molecular interventions for modulating epigenetic mechanisms might have therapeutic applications to promote cognitive maintenance through an advanced age. The SAMP8 mouse is a senescence model with AD traits in which the study of epigenetic alterations may unveil epigenetic therapies against the AD.
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Affiliation(s)
- Christian Griñán-Ferré
- Department of Pharmacology, Toxicology and Therapeutic Chemistry (Pharmacology Section) and Institute of Neuroscience, University of Barcelona and CIBERNED, Barcelona, Spain
| | - Rubén Corpas
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC, IDIBAPS and CIBERESP, Barcelona, Spain
| | - Dolors Puigoriol-Illamola
- Department of Pharmacology, Toxicology and Therapeutic Chemistry (Pharmacology Section) and Institute of Neuroscience, University of Barcelona and CIBERNED, Barcelona, Spain
| | - Verónica Palomera-Ávalos
- Department of Pharmacology, Toxicology and Therapeutic Chemistry (Pharmacology Section) and Institute of Neuroscience, University of Barcelona and CIBERNED, Barcelona, Spain
| | - Coral Sanfeliu
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC, IDIBAPS and CIBERESP, Barcelona, Spain
| | - Mercè Pallàs
- Department of Pharmacology, Toxicology and Therapeutic Chemistry (Pharmacology Section) and Institute of Neuroscience, University of Barcelona and CIBERNED, Barcelona, Spain
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26
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Sheng M, Lu H, Liu P, Li Y, Ravi H, Peng SL, Diaz-Arrastia R, Devous MD, Womack KB. Sildenafil Improves Vascular and Metabolic Function in Patients with Alzheimer's Disease. J Alzheimers Dis 2018; 60:1351-1364. [PMID: 29036811 DOI: 10.3233/jad-161006] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Alzheimer's disease (AD) is the leading cause of degenerative dementia in the aging population. Patients with AD have alterations in cerebral hemodynamic function including reduced cerebral blood flow (CBF) and cerebral metabolic rate. Therefore, improved cerebrovascular function may be an attractive goal for pharmaceutical intervention in AD. OBJECTIVE We wished to observe the acute effects of sildenafil on cerebrovascular function and brain metabolism in patients with AD. METHODS We used several novel non-invasive MRI techniques to investigate the alterations of CBF, cerebral metabolic rate of oxygen (CMRO2), and cerebrovascular reactivity (CVR) after a single dose of sildenafil administration in order to assess its physiological effects in patients with AD. CBF, CMRO2, and CVR measurements using MRI were performed before and one hour after the oral administration of 50 mg sildenafil. Baseline Montreal Cognitive Assessment score was also obtained. RESULTS Complete CBF and CMRO2 data were obtained in twelve patients. Complete CVR data were obtained in eight patients. Global CBF and CMRO2 significantly increased (p = 0.03, p = 0.05, respectively) following sildenafil administration. Voxel-wise analyses of CBF maps showed that increased CBF was most pronounced in the bilateral medial temporal lobes. CVR significantly decreased after administration of sildenafil. CONCLUSION Our data suggest that a single dose of sildenafil improves cerebral hemodynamic function and increases cerebral oxygen metabolism in patients with AD.
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Affiliation(s)
- Min Sheng
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Beijing Eden Hospital, Beijing, China
| | - Hanzhang Lu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peiying Liu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yang Li
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Harshan Ravi
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shin-Lei Peng
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Penn Presbyterian Medical Center, Philadelphia, PA, USA
| | - Michael D Devous
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kyle B Womack
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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Hou XQ, Song HP, Chen YB, Cheng SY, Fang SH, Zhang JG, Wang Q. Effects of Bushen-Yizhi formula on age-related inflammation and oxidative stress in senescence-accelerated mice. Mol Med Rep 2018; 17:6947-6960. [PMID: 29568888 PMCID: PMC5928649 DOI: 10.3892/mmr.2018.8736] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 04/27/2017] [Indexed: 11/09/2022] Open
Abstract
The present study aimed to investigate the possible effects and underlying molecular mechanism of Bushen-Yizhi formula (BSYZ), a traditional Chinese medicine, on age-related degeneration of brain physiology in senescence-accelerated mouse prone 8 (SAMP8) mice. SAMP8 mice (age, 6 months) were administered BSYZ (1.46, 2.92 and 5.84 g/kg/day) for 30 days. Morris water maze and step-down tests demonstrated that BSYZ significantly improved memory impairments in SAMP8 mice. In addition, BSYZ significantly enhanced the expression levels of peroxisome proliferator-activated receptor-γ and B-cell lymphoma extra-large, and downregulated the expression levels of inflammatory mediators, glial fibrillary acidic protein, cyclooxygenase-2, nuclear factor-κB and interleukin-1β in the brain compared with untreated SAMP8 mice. Furthermore, BSYZ reversed disordered superoxide dismutase activity, malondialdehyde content and glutathione peroxidase activity, and ameliorated apoptosis and histological alterations. The present study indicated that BSYZ may attenuate cognitive impairment in SAMP8 mice, and modulate inflammation, oxidative stress and neuronal apoptosis. These results suggested that BSYZ may have the potential to be further developed into a therapeutic agent for protection against age-related neurodegenerative diseases.
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Affiliation(s)
- Xue-Qin Hou
- Institute of Pharmacology, Taishan Medical College, Tai'an, Shandong 271016, P.R. China
| | - Hou-Pan Song
- Hunan Provincial Key Laboratory of Diagnostics in Chinese Medicine, Hunan University of Chinese Medicine, Changsha, Hunan 410208, P.R. China
| | - Yun-Bo Chen
- Design, Measurement and Evaluation in Clinical Research Center, Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Shu-Yi Cheng
- Design, Measurement and Evaluation in Clinical Research Center, Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Shu-Huan Fang
- Design, Measurement and Evaluation in Clinical Research Center, Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Ji-Guo Zhang
- Institute of Pharmacology, Taishan Medical College, Tai'an, Shandong 271016, P.R. China
| | - Qi Wang
- Design, Measurement and Evaluation in Clinical Research Center, Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
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28
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Wu Y, Li Z, Huang YY, Wu D, Luo HB. Novel Phosphodiesterase Inhibitors for Cognitive Improvement in Alzheimer's Disease. J Med Chem 2018; 61:5467-5483. [PMID: 29363967 DOI: 10.1021/acs.jmedchem.7b01370] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is one of the greatest public health challenges. Phosphodiesterases (PDEs) are a superenzyme family responsible for the hydrolysis of two second messengers: cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Since several PDE subfamilies are highly expressed in the human brain, the inhibition of PDEs is involved in neurodegenerative processes by regulating the concentration of cAMP and/or cGMP. Currently, PDEs are considered as promising targets for the treatment of AD since many PDE inhibitors have exhibited remarkable cognitive improvement effects in preclinical studies and over 15 of them have been subjected to clinical trials. The aim of this review is to summarize the outstanding progress that has been made by PDE inhibitors as anti-AD agents with encouraging results in preclinical studies and clinical trials. The binding affinity, pharmacokinetics, underlying mechanisms, and limitations of these PDE inhibitors in the treatment of AD are also reviewed and discussed.
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Affiliation(s)
- Yinuo Wu
- School of Pharmaceutical Sciences , Sun Yat-sen University , Guangzhou 510006 , P. R. China
| | - Zhe Li
- School of Pharmaceutical Sciences , Sun Yat-sen University , Guangzhou 510006 , P. R. China
| | - Yi-You Huang
- School of Pharmaceutical Sciences , Sun Yat-sen University , Guangzhou 510006 , P. R. China
| | - Deyan Wu
- School of Pharmaceutical Sciences , Sun Yat-sen University , Guangzhou 510006 , P. R. China
| | - Hai-Bin Luo
- School of Pharmaceutical Sciences , Sun Yat-sen University , Guangzhou 510006 , P. R. China
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29
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Kelly MP. Cyclic nucleotide signaling changes associated with normal aging and age-related diseases of the brain. Cell Signal 2018; 42:281-291. [PMID: 29175000 PMCID: PMC5732030 DOI: 10.1016/j.cellsig.2017.11.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 11/21/2017] [Indexed: 01/23/2023]
Abstract
Deficits in brain function that are associated with aging and age-related diseases benefit very little from currently available therapies, suggesting a better understanding of the underlying molecular mechanisms is needed to develop improved drugs. Here, we review the literature to test the hypothesis that a break down in cyclic nucleotide signaling at the level of synthesis, execution, and/or degradation may contribute to these deficits. A number of findings have been reported in both the human and animal model literature that point to brain region-specific changes in Galphas (a.k.a. Gαs or Gsα), adenylyl cyclase, 3',5'-adenosine monophosphate (cAMP) levels, protein kinase A (PKA), cAMP response element binding protein (CREB), exchange protein activated by cAMP (Epac), hyperpolarization-activated cyclic nucleotide-gated ion channels (HCNs), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), soluble and particulate guanylyl cyclase, 3',5'-guanosine monophosphate (cGMP), protein kinase G (PKG) and phosphodiesterases (PDEs). Among the most reproducible findings are 1) elevated circulating ANP and BNP levels being associated with cognitive dysfunction or dementia independent of cardiovascular effects, 2) reduced basal and/or NMDA-stimulated cGMP levels in brain with aging or Alzheimer's disease (AD), 3) reduced adenylyl cyclase activity in hippocampus and specific cortical regions with aging or AD, 4) reduced expression/activity of PKA in temporal cortex and hippocampus with AD, 5) reduced phosphorylation of CREB in hippocampus with aging or AD, 6) reduced expression/activity of the PDE4 family in brain with aging, 7) reduced expression of PDE10A in the striatum with Huntington's disease (HD) or Parkinson's disease, and 8) beneficial effects of select PDE inhibitors, particularly PDE10 inhibitors in HD models and PDE4 and PDE5 inhibitors in aging and AD models. Although these findings generally point to a reduction in cyclic nucleotide signaling being associated with aging and age-related diseases, there are exceptions. In particular, there is evidence for increased cAMP signaling specifically in aged prefrontal cortex, AD cerebral vessels, and PD hippocampus. Thus, if cyclic nucleotide signaling is going to be targeted effectively for therapeutic gain, it will have to be manipulated in a brain region-specific manner.
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Affiliation(s)
- Michy P Kelly
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina School of Medicine, 6439 Garners Ferry Road, VA Bldg 1, 3rd Floor, D-12, Columbia, SC 29209, United States.
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30
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Abstract
High levels of amyloid-β peptide (Aβ) have been related to Alzheimer's disease pathogenesis. However, in the healthy brain, low physiologically relevant concentrations of Aβ are necessary for long-term potentiation (LTP) and memory. Because cGMP plays a key role in these processes, here we investigated whether the cyclic nucleotide cGMP influences Aβ levels and function during LTP and memory. We demonstrate that the increase of cGMP levels by the phosphodiesterase-5 inhibitors sildenafil and vardenafil induces a parallel release of Aβ due to a change in the approximation of amyloid precursor protein (APP) and the β-site APP cleaving enzyme 1. Moreover, electrophysiological and behavioral studies performed on animals of both sexes showed that blocking Aβ function, by using anti-murine Aβ antibodies or APP knock-out mice, prevents the cGMP-dependent enhancement of LTP and memory. Our data suggest that cGMP positively regulates Aβ levels in the healthy brain which, in turn, boosts synaptic plasticity and memory.SIGNIFICANCE STATEMENT Amyloid-β (Aβ) is a key pathogenetic factor in Alzheimer's disease. However, low concentrations of endogenous Aβ, mimicking levels of the peptide in the healthy brain, enhance hippocampal long-term potentiation (LTP) and memory. Because the second messenger cGMP exerts a central role in LTP mechanisms, here we studied whether cGMP affects Aβ levels and function during LTP. We show that cGMP enhances Aβ production by increasing the APP/BACE-1 convergence in endolysosomal compartments. Moreover, the cGMP-induced enhancement of LTP and memory was disrupted by blockade of Aβ, suggesting that the physiological effect of the cyclic nucleotide on LTP and memory is dependent upon Aβ.
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31
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Zanoni DS, Da Silva GA, Ezra‐Elia R, Carvalho M, Quitzan JG, Ofri R, Laus JL, Laufer‐Amorim R. Histological, morphometric, protein and gene expression analyses of rat retinas with ischaemia-reperfusion injury model treated with sildenafil citrate. Int J Exp Pathol 2017; 98:147-157. [PMID: 28849621 PMCID: PMC5573770 DOI: 10.1111/iep.12233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 04/25/2017] [Indexed: 12/27/2022] Open
Abstract
The aim of this study was to better understand the role of apoptosis in a retinal ischaemia-reperfusion injury model and to determine whether sildenafil citrate treatment can prevent retinal cell apoptosis. Thirty-six rats were divided into a control group (n = 6) and two experimentally induced ischaemia-reperfusion groups (7 and 21 days; n = 15 per group). The induced ischaemia-reperfusion groups were treated with sildenafil for 7 and 21 days (n = 10 per group), and 10 animals were treated with a placebo for the same period (n = 5 per group). Paracentesis of the anterior chamber was performed with a 30-G needle attached to a saline solution (0.9%) bag positioned at a height of 150 cm above the eye for 60 min. Intraocular pressure was measured by rebound tonometer (TonoVet® ). The eyes were analysed by histology and morphometry, and by immunohistochemistry and qRT-PCR for expression of Caspase-7, Caspase-6, Caspase-9, Tnf-r2, Fas-l, Bcl-2 and Bax. Sildenafil-treated animals showed lower levels of histopathological changes (inflammatory, cellular and tissue) than their placebo-treated counterparts at both 7 and 21 days. The retinal ganglion cell layer (RGC) was preserved in the sildenafil groups (SG), with a cell count closer to control than in the placebo groups (PG). Caspase-7 expression was significantly higher in both treated groups at 7 days compared to controls. Gene expression levels in both treatment groups differed from the controls, but in SG Bax and Caspase-6 expression levels were similar to control animals. These results suggest that the main mechanism of retinal cell death in this model is apoptosis, as there is an increase in pro-apoptotic factors and decrease in the anti-apoptotic ones. Also, sildenafil seems to protect the retinal ganglion cell layer from apoptosis. Cell survival was evident in the histological and morphometric analyses, and sildenafil treatment had a protective effect in the apoptosis pathways, with gene expression levels in SG similar to the controls.
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Affiliation(s)
- Diogo S. Zanoni
- Department of Veterinary ClinicSchool of Veterinary Medicine and Animal ScienceUniversity Estadual PaulistaBotucatuSPBrazil
| | - Germana A. Da Silva
- Department of Veterinary Clinic and SurgerySchool of Veterinary Medicine and Animal ScienceUniversity Estadual PaulistaJaboticabalSPBrazil
| | - Raaya Ezra‐Elia
- Koret School of Veterinary MedicineThe Hebrew University of JerusalemIsrael
| | - Márcio Carvalho
- Department of Veterinary ClinicSchool of Veterinary Medicine and Animal ScienceUniversity Estadual PaulistaBotucatuSPBrazil
| | - Juliany G. Quitzan
- Department of Surgery and AnesthesiologySchool of Veterinary Medicine and Animal ScienceUniversity Estadual PaulistaBotucatuSPBrazil
| | - Ron Ofri
- Koret School of Veterinary MedicineThe Hebrew University of JerusalemIsrael
| | - José L. Laus
- Department of Veterinary Clinic and SurgerySchool of Veterinary Medicine and Animal ScienceUniversity Estadual PaulistaJaboticabalSPBrazil
| | - Renee Laufer‐Amorim
- Department of Veterinary ClinicSchool of Veterinary Medicine and Animal ScienceUniversity Estadual PaulistaBotucatuSPBrazil
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32
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Castano-Prat P, Perez-Zabalza M, Perez-Mendez L, Escorihuela RM, Sanchez-Vives MV. Slow and Fast Neocortical Oscillations in the Senescence-Accelerated Mouse Model SAMP8. Front Aging Neurosci 2017; 9:141. [PMID: 28620295 PMCID: PMC5449444 DOI: 10.3389/fnagi.2017.00141] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/27/2017] [Indexed: 11/28/2022] Open
Abstract
The senescence-accelerated mouse prone 8 (SAMP8) model is characterized by accelerated, progressive cognitive decline as well as Alzheimer’s disease (AD)-like neurodegenerative changes, and resembles the etiology of multicausal, sporadic late-onset/age-related AD in humans. Our aim was to find whether these AD-like pathological features, together with the cognitive deficits present in the SAMP8 strain, are accompanied by disturbances in cortical network activity with respect to control mice (SAM resistance 1, SAMR1) and, if so, how the alterations in cortical activity progress with age. For this purpose, we characterized the extracellular spontaneous oscillatory activity in different regions of the cerebral cortex of SAMP8 and SAMR1 mice under ketamine anesthesia at 5 and 7 months of age. Under these conditions, slow oscillations and fast rhythms generated in the cortical network were recorded and different parameters of these oscillations were quantified and compared between SAMP8 and their control, SAMR1 mice. The average frequency of slow oscillations in SAMP8 mice was decreased with respect to the control mice at both studied ages. An elongation of the silent periods or Down states was behind the decreased slow oscillatory frequency while the duration of active or Up states remained stable. SAMP8 mice also presented increased cycle variability and reduced high frequency components during Down states. During Up states, the power peak in the gamma range was displaced towards lower frequencies in all the cortical areas of SAMP8 with respect to control mice suggesting that the spectral profile of SAMP8 animals is shifted towards lower frequencies. This shift is reminiscent to one of the principal hallmarks of electroencephalography (EEG) abnormalities in patients with Alzheimer’s disease, and adds evidence in support of the suitability of the SAMP8 mouse as a model of this disease. Although some of the differences between SAMP8 and control mice were emphasized with age, the evolution of the studied parameters as SAMR1 mice got older indicates that the SAMR1 phenotype tends to converge with that of SAMP8 animals. To our knowledge, this is the first systematic characterization of the cortical slow and fast rhythms in the SAMP8 strain and it provides useful insights about the cellular and synaptic mechanisms underlying the reported alterations.
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Affiliation(s)
- Patricia Castano-Prat
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)Barcelona, Spain
| | - Maria Perez-Zabalza
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)Barcelona, Spain
| | - Lorena Perez-Mendez
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)Barcelona, Spain
| | - Rosa M Escorihuela
- Departament de Psiquiatria i Medicina Legal, Institut de Neurociències, Universitat Autònoma de BarcelonaBarcelona, Spain
| | - Maria V Sanchez-Vives
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)Barcelona, Spain.,ICREABarcelona, Spain
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33
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SIRT2 inhibition modulate glutamate and serotonin systems in the prefrontal cortex and induces antidepressant-like action. Neuropharmacology 2017; 117:195-208. [DOI: 10.1016/j.neuropharm.2017.01.033] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/11/2017] [Accepted: 01/29/2017] [Indexed: 11/20/2022]
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34
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Heckman PRA, Blokland A, Prickaerts J. From Age-Related Cognitive Decline to Alzheimer's Disease: A Translational Overview of the Potential Role for Phosphodiesterases. ADVANCES IN NEUROBIOLOGY 2017; 17:135-168. [PMID: 28956332 DOI: 10.1007/978-3-319-58811-7_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Phosphodiesterase inhibitors (PDE-Is) are pharmacological compounds enhancing cAMP and/or cGMP signaling. Both these substrates affect neural communication by influencing presynaptic neurotransmitter release and postsynaptic intracellular pathways after neurotransmitter binding to its receptor. Both cAMP and cGMP play an important role in a variety of cellular functions including neuroplasticity and neuroprotection. This chapter provides a translational overview of the effects of different classes of PDE-Is on cognition enhancement in age-related cognitive decline and Alzheimer's disease (AD). The most effective PDE-Is in preclinical models of aging and AD appear to be PDE2-Is, PDE4-Is and PDE5-Is. Clinical studies are relatively sparse and so far PDE1-Is and PDE4-Is showed some promising results. In the future, the demonstration of clinical proof of concept and the generation of isoform selective PDE-Is are the hurdles to overcome in developing safe and efficacious novel PDE-Is for the treatment of age-related cognitive decline and cognitive dysfunction in AD.
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Affiliation(s)
- Pim R A Heckman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands
| | - Arjan Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands
| | - Jos Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands.
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35
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Moreno LCGEI, Puerta E, Suárez-Santiago JE, Santos-Magalhães NS, Ramirez MJ, Irache JM. Effect of the oral administration of nanoencapsulated quercetin on a mouse model of Alzheimer's disease. Int J Pharm 2016; 517:50-57. [PMID: 27915007 DOI: 10.1016/j.ijpharm.2016.11.061] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 12/19/2022]
Abstract
Quercetin has been identified as a promising compound with a neuroprotective potential against age-related neurodegenerative diseases such as Alzheimer's disease (AD). Nevertheless, the clinical application of quercetin is hampered by its low oral bioavailability. The aim of this work was to evaluate the capability of nanoencapsulated quercetin in zein nanoparticles (NPQ), that significantly improves the oral absorption and bioavailability of the flavonoid, as potential oral treatment for AD. For this purpose, SAMP8 mice were orally treated for two months with either NPQ (25mg/kg every 48h) or a solution of quercetin (Q; 25mg/kg daily). NPQ displayed a size of 260nm and a payload of about 70μg/mg. For Q, no significant effects were observed in animals. On the contrary, the oral administration of NPQ improved the cognition and memory impairments characteristics of SAMP8 mice. These observations appeared to be related with a decreased expression of the hippocampal astrocyte marker GFAP. Furthermore, significant levels of quercetin were quantified in the brain of mice treated with nanoparticles. These findings highlight the potential of zein nanoparticles to promote the oral absorption of quercetin as well as the therapeutic potential of this flavonoid in AD pathogenesis.
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Affiliation(s)
- Lina Clara Gayoso E Ibiapina Moreno
- Department of Pharmacy and Pharmaceutical Technology, University of Navarra, Pamplona, Spain; Immunopathology Keizo-Asami Laboratory, Federal University of Pernambuco, Recife, Brazil
| | - Elena Puerta
- Department of Pharmacology and Toxicology, University of Navarra, Pamplona, Spain
| | | | | | - Maria J Ramirez
- Department of Pharmacology and Toxicology, University of Navarra, Pamplona, Spain
| | - Juan M Irache
- Department of Pharmacy and Pharmaceutical Technology, University of Navarra, Pamplona, Spain.
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36
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Gómez-Vallejo V, Ugarte A, García-Barroso C, Cuadrado-Tejedor M, Szczupak B, Dopeso-Reyes IG, Lanciego JL, García-Osta A, Llop J, Oyarzabal J, Franco R. Pharmacokinetic investigation of sildenafil using positron emission tomography and determination of its effect on cerebrospinal fluid cGMP levels. J Neurochem 2016; 136:403-15. [PMID: 26641206 DOI: 10.1111/jnc.13454] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/17/2015] [Accepted: 11/20/2015] [Indexed: 11/29/2022]
Abstract
Sildenafil (Viagra) is a selective inhibitor of phosphodiesterase type 5 (PDE5), which degrades cyclic guanosine monophosphate to the linear nucleotide. Sildenafil is acutely used in erectile dysfunction and chronically in pulmonary hypertension. Evidence in the last decade shows that sildenafil may have potential as a therapeutic option for Alzheimer's disease or other neurodegenerative disorders. The purpose of this work was to explore whether sildenafil crosses the blood-brain barrier. Pharmacokinetic properties of sildenafil in rodents were investigated using (11) C-radiolabeling followed by in vivo positron emission tomography (PET) and ex vivo tissue dissection and gamma counting. PET results in rats suggest penetration into the central nervous system. Ex vivo data in perfused animals suggest that trapping of [(11) C]sildenafil within the cerebral vascular endothelium limits accumulation in the central nervous system parenchyma. Peroral sildenafil administration to Macaca fascicularis and subsequent chemical analysis of plasma and cerebrospinal fluid (CSF) using liquid chromatography coupled with tandem mass spectrometry showed that drug content in the CSF was high enough to achieve PDE5 inhibition, which was also demonstrated by the significant increases in CSF cyclic guanosine monophosphate levels. Central actions of sildenafil include both relaxation of the cerebral vasculature and inhibition of PDE5 in neurons and glia. This central action of sildenafil may underlie its efficacy in neuroprotection models, and may justify the continued search for a PDE5 ligand suitable for PET imaging. Sildenafil interacts with phosphodiesterase type 5 (PDE5) expressed in the endothelium and/or smooth muscle cells of brain vessels and also crosses the blood-brain barrier to interact with PDE5 expressed in brain cells. At therapeutic doses, the concentration of sildenafil in the cerebrospinal fluid (CSF) is high enough to inhibit PDE5 in the neural cells (neurons and glia). In turn, the concentration of cGMP likely increases in parenchymal cells and, as shown in this report, in the CSF. Read the Editorial Highlight for this article on page 220. Cover Image for this issue: doi: 10.1111/jnc.13302.
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Affiliation(s)
| | - Ana Ugarte
- Small Molecule Discovery Platform, Molecular Therapeutics Program, Centre for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
| | - Carolina García-Barroso
- Neurobiology of Alzheimer's disease, Neurosciences Division, Centre for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
| | - Mar Cuadrado-Tejedor
- Neurobiology of Alzheimer's disease, Neurosciences Division, Centre for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,Anatomy Department, School of Medicine, University of Navarra, Pamplona, Spain
| | | | - Iria G Dopeso-Reyes
- Neurosciences Division, Centre for Applied Medical Research, CIMA, University of Navarra, Pamplona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Pamplona, Spain.,Instituto de Investigaciones Sanitarias de Navarra (IdiSNA), Pamplona, Spain
| | - José L Lanciego
- Neurosciences Division, Centre for Applied Medical Research, CIMA, University of Navarra, Pamplona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Pamplona, Spain.,Instituto de Investigaciones Sanitarias de Navarra (IdiSNA), Pamplona, Spain
| | - Ana García-Osta
- Neurobiology of Alzheimer's disease, Neurosciences Division, Centre for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
| | - Jordi Llop
- Radiochemistry and Nuclear Imaging Group, CIC biomaGUNE, San Sebastian, Spain
| | - Julen Oyarzabal
- Small Molecule Discovery Platform, Molecular Therapeutics Program, Centre for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
| | - Rafael Franco
- Neurobiology of Alzheimer's disease, Neurosciences Division, Centre for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
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Takagane K, Nojima J, Mitsuhashi H, Suo S, Yanagihara D, Takaiwa F, Urano Y, Noguchi N, Ishiura S. Aβ induces oxidative stress in senescence-accelerated (SAMP8) mice. Biosci Biotechnol Biochem 2015; 79:912-8. [PMID: 25612552 DOI: 10.1080/09168451.2014.1002449] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
According to the amyloid hypothesis, amyloid β accumulates in brains with Alzheimer's disease (AD) and triggers cell death and memory deficit. Previously, we developed a rice Aβ vaccine expressing Aβ, which reduced brain Aβ levels in the Tg2576 mouse model of familial AD. We used senescence-accelerated SAMP8 mice as a model of sporadic AD and investigated the relationship between Aβ and oxidative stress. Insoluble Aβ and 4-hydroxynonenal (4-HNE) levels tended to be reduced in SAMP8 mice-fed the rice Aβ vaccine. We attempted to clarify the relationship between oxidative stress and Aβ in vitro. Addition of Aβ peptide to the culture medium resulted in an increase in 4-HNE levels in SH-SY5Y cells. Tg2576 mice, which express large amounts of Aβ in their brain, also exhibited increased 4-HNE levels; this increase was inhibited by the Aβ vaccine. These results indicate that Aβ induces oxidative stress in cultured cells and in the mouse brain.
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Affiliation(s)
- Kurara Takagane
- a Department of Biological Sciences, Graduate School of Science , The University of Tokyo , Tokyo , Japan
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Peixoto CA, Nunes AKS, Garcia-Osta A. Phosphodiesterase-5 Inhibitors: Action on the Signaling Pathways of Neuroinflammation, Neurodegeneration, and Cognition. Mediators Inflamm 2015; 2015:940207. [PMID: 26770022 PMCID: PMC4681825 DOI: 10.1155/2015/940207] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 11/08/2015] [Indexed: 12/16/2022] Open
Abstract
Phosphodiesterase type 5 inhibitors (PDE5-Is) have recently emerged as a potential therapeutic strategy for neuroinflammatory, neurodegenerative, and memory loss diseases. Mechanistically, PDE5-Is produce an anti-inflammatory and neuroprotection effect by increasing expression of nitric oxide synthases and accumulation of cGMP and activating protein kinase G (PKG), the signaling pathway of which is thought to play an important role in the development of several neurodiseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). The aim of this paper was to review present knowledge of the signaling pathways that underlie the use of PDE5-Is in neuroinflammation, neurogenesis, learning, and memory.
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Affiliation(s)
- Christina Alves Peixoto
- 1Laboratório de Ultraestrutura, Centro de Pesquisa Aggeu Magalhães (FIOCRUZ), 50.740-465 Recife, PE, Brazil
- *Christina Alves Peixoto:
| | - Ana Karolina Santana Nunes
- 1Laboratório de Ultraestrutura, Centro de Pesquisa Aggeu Magalhães (FIOCRUZ), 50.740-465 Recife, PE, Brazil
- 2Universidade Federal de Pernambuco, 50.670-901 Recife, PE, Brazil
| | - Ana Garcia-Osta
- 3Neurobiology of Alzheimer's disease, Neurosciences Division, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
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Orejana L, Barros-Miñones L, Jordan J, Cedazo-Minguez A, Tordera RM, Aguirre N, Puerta E. Sildenafil Decreases BACE1 and Cathepsin B Levels and Reduces APP Amyloidogenic Processing in the SAMP8 Mouse. J Gerontol A Biol Sci Med Sci 2014; 70:675-85. [DOI: 10.1093/gerona/glu106] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 06/08/2014] [Indexed: 12/21/2022] Open
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40
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Modulating nitric oxide signaling in the CNS for Alzheimer's disease therapy. Future Med Chem 2014; 5:1451-68. [PMID: 23919554 DOI: 10.4155/fmc.13.111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Nitric oxide (NO)/solube GC (sGC)/cGMP signaling is important for modulating synaptic transmission and plasticity in the hippocampus and cerebral cortex, which are critical for learning and memory. Physiological concentrations of NO also elicit anti-apoptotic/prosurvival effects against various neurotoxic challenges and brain insults through multiple mechanisms. Depression of the NO/sGC pathway is a feature of Alzheimer's disease (AD), attributed to amyloid-β neuropathology, and altered expression and activity of NOS, sGC and PDE enzymes. Different classes of NO-releasing hybrid drugs, including nomethiazoles, NO-NSAIDs and NO-acetylcholinesterase inhibitors were designed to deliver low concentrations of exogenous NO to the CNS while targeting other underlying disease mechanisms, such as excitotoxicity, neuro-inflammation and acetylcholine deficiency, respectively. Incorporating a NO-donating moiety may also reduce gastrointestinal and liver toxicity of the parent drugs. Progress has also been made in targeting downstream sGC and PDE enzymes. The PDE9 inhibitor PF-04447943 has completed Phase II clinical trials for AD. The search for effective NO-donating hybrid drugs, CNS-targeting sGC stimulators/activators and selective PDE inhibitors is an important goal for pharmacotherapy that manipulates NO biochemical pathways involved in cognitive function and neuroprotection. Rigorous preclinical validation of target engagement, and optimization of pharmacokinetic and toxicity profiles are likely to advance more drug candidates into clinical trials for mild cognitive impairment and early stage AD.
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41
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Stimulation of neural stem cell proliferation by inhibition of phosphodiesterase 5. Stem Cells Int 2014; 2014:878397. [PMID: 24550991 PMCID: PMC3914480 DOI: 10.1155/2014/878397] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 11/20/2013] [Accepted: 11/24/2013] [Indexed: 01/25/2023] Open
Abstract
The involvement of nitric oxide (NO) and cyclic GMP (cGMP) in neurogenesis has been progressively unmasked over the last decade. Phosphodiesterase 5 (PDE5) specifically degrades cGMP and is highly abundant in the mammalian brain. Inhibition of cGMP hydrolysis by blocking PDE5 is a possible strategy to enhance the first step of neurogenesis, proliferation of neural stem cells (NSC). In this work, we have studied the effect on cell proliferation of 3 inhibitors with different selectivity and potency for PDE5, T0156, sildenafil, and zaprinast, using subventricular zone-(SVZ-) derived NSC cultures. We observed that a short- (6 h) or a long-term (24 h) treatment with PDE5 inhibitors increased SVZ-derived NSC proliferation. Cell proliferation induced by PDE5 inhibitors was dependent on the activation of the mitogen-activated protein kinase (MAPK) and was abolished by inhibitors of MAPK signaling, soluble guanylyl cyclase, and protein kinase G. Moreover, sildenafil neither activated ERK1/2 nor altered p27Kip1 levels, suggesting the involvement of pathways different from those activated by T0156 or zaprinast. In agreement with the present results, PDE5 inhibitors may be an interesting therapeutic approach for enhancing the proliferation stage of adult neurogenesis.
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Tripchlorolide improves age-associated cognitive deficits by reversing hippocampal synaptic plasticity impairment and NMDA receptor dysfunction in SAMP8 mice. Behav Brain Res 2014; 258:8-18. [DOI: 10.1016/j.bbr.2013.10.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/29/2013] [Accepted: 10/03/2013] [Indexed: 02/02/2023]
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Ramos-Rodriguez JJ, Molina-Gil S, Rey-Brea R, Berrocoso E, Garcia-Alloza M. Specific serotonergic denervation affects tau pathology and cognition without altering senile plaques deposition in APP/PS1 mice. PLoS One 2013; 8:e79947. [PMID: 24278223 PMCID: PMC3837012 DOI: 10.1371/journal.pone.0079947] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 09/27/2013] [Indexed: 11/19/2022] Open
Abstract
Senile plaques and neurofibrillary tangles are major neuropathological features of Alzheimer's Disease (AD), however neuronal loss is the alteration that best correlates with cognitive impairment in AD patients. Underlying neurotoxic mechanisms are not completely understood although specific neurotransmission deficiencies have been observed in AD patients and, in animal models, cholinergic and noradrenergic denervation may increase amyloid-beta deposition and tau phosphorylation in denervated areas. On the other hand brainstem neurodegeneration has been suggested as an initial event in AD, and serotonergic dysfunction, as well as reductions in raphe neurones density, have been reported in AD patients. In this study we addressed whether specific serotonergic denervation, by administering 5,7-dihydroxitriptamine (5,7-DHT) in the raphe nuclei, could also worsen central pathology in APPswe/PS1dE9 mice or interfere with learning and memory activities. In our hands specific serotonergic denervation increased tau phosphorylation in denervated cortex, without affecting amyloid-beta (Aβ) pathology. We also observed that APPswe/PS1dE9 mice lesioned with 5,7-DHT were impaired in the Morris water maze test, supporting a synergistic effect of the serotonergic denervation and the presence of APP/PS1 transgenes on learning and memory impairment. Altogether our data suggest that serotonergic denervation may interfere with some pathological aspects observed in AD, including tau phosphorylation or cognitive impairment, without affecting Aβ pathology, supporting a differential role of specific neurotransmitter systems in AD.
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Affiliation(s)
| | - Sara Molina-Gil
- Division of Physiology, School of Medicine, University of Cadiz, Cadiz, Spain
| | - Raquel Rey-Brea
- Department of Neuroscience, School of Medicine, University of Cadiz, Cadiz, Spain
- Centro de Investigación Biomédica en Red de Salud Mental, Instituto de Salud Carlos III. Madrid, Spain
| | - Esther Berrocoso
- Department of Neuroscience, School of Medicine, University of Cadiz, Cadiz, Spain
- Centro de Investigación Biomédica en Red de Salud Mental, Instituto de Salud Carlos III. Madrid, Spain
| | - Monica Garcia-Alloza
- Division of Physiology, School of Medicine, University of Cadiz, Cadiz, Spain
- * E-mail:
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Cheng XR, Cui XL, Zheng Y, Zhang GR, Li P, Huang H, Zhao YY, Bo XC, Wang SQ, Zhou WX, Zhang YX. Nodes and biological processes identified on the basis of network analysis in the brain of the senescence accelerated mice as an Alzheimer's disease animal model. Front Aging Neurosci 2013; 5:65. [PMID: 24194717 PMCID: PMC3810591 DOI: 10.3389/fnagi.2013.00065] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 10/10/2013] [Indexed: 12/11/2022] Open
Abstract
Harboring the behavioral and histopathological signatures of Alzheimer's disease (AD), senescence accelerated mouse-prone 8 (SAMP8) mice are currently considered a robust model for studying AD. However, the underlying mechanisms, prioritized pathways and genes in SAMP8 mice linked to AD remain unclear. In this study, we provide a biological interpretation of the molecular underpinnings of SAMP8 mice. Our results were derived from differentially expressed genes in the hippocampus and cerebral cortex of SAMP8 mice compared to age-matched SAMR1 mice at 2, 6, and 12 months of age using cDNA microarray analysis. On the basis of PPI, MetaCore and the co-expression network, we constructed a distinct genetic sub-network in the brains of SAMP8 mice. Next, we determined that the regulation of synaptic transmission and apoptosis were disrupted in the brains of SAMP8 mice. We found abnormal gene expression of RAF1, MAPT, PTGS2, CDKN2A, CAMK2A, NTRK2, AGER, ADRBK1, MCM3AP, and STUB1, which may have initiated the dysfunction of biological processes in the brains of SAMP8 mice. Specifically, we found microRNAs, including miR-20a, miR-17, miR-34a, miR-155, miR-18a, miR-22, miR-26a, miR-101, miR-106b, and miR-125b, that might regulate the expression of nodes in the sub-network. Taken together, these results provide new insights into the biological and genetic mechanisms of SAMP8 mice and add an important dimension to our understanding of the neuro-pathogenesis in SAMP8 mice from a systems perspective.
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Affiliation(s)
- Xiao-Rui Cheng
- Department of Neuroimmunopharmacology, Beijing Institute of Pharmacology and Toxicology Beijing, China
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Regulation of hippocampal cGMP levels as a candidate to treat cognitive deficits in Huntington's disease. PLoS One 2013; 8:e73664. [PMID: 24040016 PMCID: PMC3764028 DOI: 10.1371/journal.pone.0073664] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 07/19/2013] [Indexed: 01/05/2023] Open
Abstract
Huntington’s disease (HD) patients and mouse models show learning and memory impairment associated with hippocampal dysfunction. The neuronal nitric oxide synthase/3',5'-cyclic guanosine monophosphate (nNOS/cGMP) pathway is implicated in synaptic plasticity, and in learning and memory processes. Here, we examined the nNOS/cGMP pathway in the hippocampus of HD mice to determine whether it can be a good therapeutic target for cognitive improvement in HD. We analyzed hippocampal nNOS and phosphodiesterase (PDE) 5 and 9 levels in R6/1 mice, and cGMP levels in the hippocampus of R6/1, R6/2 and HdhQ7/Q111 mice, and of HD patients. We also investigated whether sildenafil, a PDE5 inhibitor, could improve cognitive deficits in R6/1 mice. We found that hippocampal cGMP levels were 3-fold lower in 12-week-old R6/1 mice, when they show deficits in object recognition memory and in passive avoidance learning. Consistent with hippocampal cGMP levels, nNOS levels were down-regulated, while there were no changes in the levels of PDE5 and PDE9 in R6/1 mice. A single intraperitoneal injection of sildenafil (3 mg/Kg) immediately after training increased cGMP levels, and improved memory in R6/1 mice, as assessed by using the novel object recognition and the passive avoidance test. Importantly, cGMP levels were also reduced in R6/2 mouse and human HD hippocampus. Therefore, the regulation of hippocampal cGMP levels can be a suitable treatment for cognitive impairment in HD.
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Phosphodiesterase-5 inhibitor sildenafil prevents neuroinflammation, lowers beta-amyloid levels and improves cognitive performance in APP/PS1 transgenic mice. Behav Brain Res 2013; 250:230-7. [PMID: 23685322 DOI: 10.1016/j.bbr.2013.05.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/05/2013] [Accepted: 05/09/2013] [Indexed: 12/30/2022]
Abstract
Memory deficit is a marker of Alzheimer's disease (AD) that has been highly associated with the dysfunction of cyclic GMP (cGMP) signaling and an ongoing inflammatory process. Phosphodiesterase-5 (PDE5) inhibitors prevent the breakdown of cGMP and are currently studied as a possible target for cognitive enhancement. However, it is still unknown whether inhibition of PDE5 reversed β-amyloid peptide (Aβ)-induced neuroinflammation in APP/PS1 transgenic (Tg APP/PS1) mice. The present study evaluated the cognitive behaviors, inflammatory mediators, and cGMP/PKG/pCREB signaling in 15-month-old Tg APP/PS1 mice and age-matched wild-type (WT) mice that were treated with PDE5 inhibitor sildenafil and the inhibitor of cGMP-dependent protein kinase Rp-8-Br-PET-cGMPS. In comparison with WT mice, Tg APP/PS1 mice were characterized by impaired cognitive ability, neuroinflammatory response, and down-regulated cGMP signaling. Sildenafil reversed these memory deficits and cGMP/PKG/pCREB signaling dysfunction; it also reduced both the soluble Aβ1-40 and Aβ1-42 levels in the hippocampus. These effects of sildenafil were prevented by intra-hippocampal infusion of the Rp-8-Br-PET-cGMPS. These results suggest that sildenafil could restore cognitive deficits in Tg APP/PS1 mice by the regulation of PKG/pCREB signaling, anti-inflammatory response and reduction of Aβ levels.
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47
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Metallothioneins I/II are involved in the neuroprotective effect of sildenafil in focal brain injury. Neurochem Int 2012. [PMID: 23178801 DOI: 10.1016/j.neuint.2012.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We recently reported that administration of the non-selective cyclic GMP-phosphodiesterase (cGMP-PDE) inhibitor zaprinast to cortically cryoinjured rats results three days post-lesion in reduced neuronal cell death that was associated to decreased macrophage/microglial activation and oxidative stress and increased astrogliosis and angiogenesis. Similar effects have been observed in cryoinjured animals overexpressing metallothioneins I/II (MT-I/II), metal-binding cysteine-rich proteins that are up-regulated in response to injury. In this work we have examined the effect of administration of the selective PDE5 inhibitor sildenafil (10mg/kg, sc) 2h before and 24 and 48h after induction of cortical cryolesion in wild-type and MT-I/II-deficient mice. Our results show that in wild-type animals sildenafil induces similar changes in glial reactivity, angiogenesis and antioxidant and antiapoptotic effects in the cryolesioned cortex as those observed in rats with zaprinast, indicating that inhibition of PDE5 is responsible for the neuroprotective actions. However, these effects were not observed in mice deficient in MT-I/II. We further show that sildenafil significantly increases MT-I/II protein levels in homogenates of lesioned cortex and MT-I/II immunostaining in glial cells around the lesion. Taken together these results indicate that cGMP-mediated pathways regulate expression of MT-I/II and support the involvement of these proteins in the neuroprotective effects of sildenafil in focal brain lesion.
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Palmeri A, Privitera L, Giunta S, Loreto C, Puzzo D. Inhibition of phosphodiesterase-5 rescues age-related impairment of synaptic plasticity and memory. Behav Brain Res 2012; 240:11-20. [PMID: 23174209 DOI: 10.1016/j.bbr.2012.10.060] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/26/2012] [Accepted: 10/30/2012] [Indexed: 12/14/2022]
Abstract
Aging is characterized by a progressive cognitive decline that leads to memory impairment. Because the cyclic nucleotide cascade is essential for the integrity of synaptic function and memory, and it is down-regulated during aging and in neurodegenerative disorders, we investigated whether an increase in cGMP levels might rescue age-related synaptic and memory deficits in mice. We demonstrated that acute perfusion with the phosphodiesterase-5 inhibitor sildenafil (50 nM) ameliorated long-term potentiation in hippocampal slices from 26-30-month-old mice. Moreover, chronic intraperitoneal injection of sildenafil (3mg/kg for 3 weeks) improved age-related spatial learning and reference memory as tested by the Morris Water Maze, and recognition memory as tested by the Object Recognition Test. Finally, sildenafil restored central cAMP responsive element-binding protein (CREB) phosphorylation, which is crucial for synaptic plasticity and memory. Our data suggest that inhibition of phosphodiesterase-5 may be beneficial to treat age-related cognitive dysfunction in a physiological mouse model of aging.
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Affiliation(s)
- Agostino Palmeri
- Department of Bio-Medical Sciences - Section of Physiology, University of Catania, Catania, 95125, Italy
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Dobarro M, Orejana L, Aguirre N, Ramírez MJ. Propranolol restores cognitive deficits and improves amyloid and Tau pathologies in a senescence-accelerated mouse model. Neuropharmacology 2012; 64:137-44. [PMID: 22824191 DOI: 10.1016/j.neuropharm.2012.06.047] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/19/2012] [Accepted: 06/24/2012] [Indexed: 11/25/2022]
Abstract
Ageing is associated with a deterioration of cognitive performance and with increased risk of neurodegenerative disorders. Hypertension is the most-prevalent modifiable risk factor for cardiovascular morbidity and mortality worldwide, and clinical data suggest that hypertension is a risk factor for Alzheimer's disease (AD). In the present study we tested whether propranolol, a β-receptor antagonist commonly used as antihypertensive drug, could ameliorate the cognitive impairments and increases in AD-related markers shown by the senescence-accelerated mouse prone-8 (SAMP8). Propranolol administration (5 mg/kg for 3 weeks) to 6-month-old SAMP8 mice attenuated cognitive memory impairments shown by these mice in the novel object recognition test. In the hippocampus of SAMP8 mice it has been found increases in Aβ(42) levels, the principal constituent of amyloid plaques observed in AD, accompanied by both an increased expression of the cleaving enzyme BACE1 and a decreased expression of the degrading enzyme IDE. All these effects were reversed by propranolol treatment. Tau hyperphosphorylation (PHF-1 epitope) shown by SAMP8 mice at this age was also decreased in the hippocampus of propranolol-treated mice, an effect probably related to a decrease in JNK1 expression. Interestingly, propranolol also phosphorylated Akt in SAMP8 mice, which was associated with an increase of glycogen synthase kinase-3β phosphorylation, contributing therefore to the reductions in Tau hyperphosphorylation. Synaptic pathology in SAMP8 mice, as shown by decreases in synaptophysin and BDNF, was also counteracted by propranolol treatment. Overall, propranolol might be beneficial in age-related brain dysfunction and could be an emerging candidate for the treatment of other neurodegenerative diseases. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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Affiliation(s)
- Marta Dobarro
- Department of Pharmacology, University of Navarra, C/ Irunlarrea 1, 31008 Pamplona, Spain
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50
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Puerta E, Barros-Miñones L, Hervias I, Gomez-Rodriguez V, Orejana L, Pizarro N, de la Torre R, Jordán J, Aguirre N. Long-lasting neuroprotective effect of sildenafil against 3,4-methylenedioxymethamphetamine- induced 5-hydroxytryptamine deficits in the rat brain. J Neurosci Res 2011; 90:518-28. [PMID: 21948520 DOI: 10.1002/jnr.22759] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 06/14/2011] [Accepted: 07/03/2011] [Indexed: 11/11/2022]
Abstract
Sildenafil, given shortly before 3,4-methylenedioxymethamphetamine (MDMA), affords protection against 5-hydroxytryptamine (5-HT) depletions caused by this amphetamine derivative by an acute preconditioning-like mechanism. Because acute and delayed preconditionings do not share the same mechanisms, we investigated whether sildenafil would also protect the 5-HT system of the rat if given 24 hr before MDMA. For this, MDMA (3 × 5 mg/kg i.p., every 2 hr) was administered to rats previously treated with sildenafil (8 mg/kg p.o.). One week later, 5-HT content and 5-HT transporter density were measured in the striatum, frontal cortex, and hippocampus of the rats. Our findings indicate that sildenafil afforded significant protection against MDMA-induced 5-HT deficits without altering the acute hyperthermic response to MDMA or its metabolic disposition. Sildenafil promoted ERK1/2 activation an effect that was paralleled by an increase in MnSOD expression that persisted 24 hr later. In addition, superoxide and superoxide-derived oxidants, shown by ethidium fluorescence, increased after the last MDMA injection, an effect that was prevented by sildenafil pretreatment. Similarly, MDMA increased nitrotyrosine concentration in the hippocampus, an effect not shown by sildenafil-pretreated rats. In conclusion, our data demonstrate that sildenafil produces a significant, long-lasting neuroprotective effect against MDMA-induced 5-HT deficits. This effect is apparently mediated by an increased expression of MnSOD and a subsequent reduced susceptibility to the oxidative stress caused by MDMA.
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Affiliation(s)
- Elena Puerta
- Department of Pharmacology, School of Pharmacy, University of Navarra, Pamplona, Spain
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