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Memory Disorders Related to Hippocampal Function: The Interest of 5-HT 4Rs Targeting. Int J Mol Sci 2021; 22:ijms222112082. [PMID: 34769511 PMCID: PMC8584667 DOI: 10.3390/ijms222112082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/30/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022] Open
Abstract
The hippocampus has long been considered as a key structure for memory processes. Multilevel alterations of hippocampal function have been identified as a common denominator of memory impairments in a number of psychiatric and neurodegenerative diseases. For many years, the glutamatergic and cholinergic systems have been the main targets of therapeutic treatments against these symptoms. However, the high rate of drug development failures has left memory impairments on the sideline of current therapeutic strategies. This underscores the urgent need to focus on new therapeutic targets for memory disorders, such as type 4 serotonin receptors (5-HT4Rs). Ever since the discovery of their expression in the hippocampus, 5-HT4Rs have gained growing interest for potential use in the treatment of learning and memory impairments. To date, much of the researched information gathered by scientists from both animal models and humans converge on pro-mnesic and anti-amnesic properties of 5-HT4Rs activation, although the mechanisms at work require more work to be fully understood. This review addresses a fundamental, yet poorly understood set of evidence of the potential of 5-HT4Rs to re-establish or limit hippocampal alterations related to neurological diseases. Most importantly, the potential of 5-HT4Rs is translated by refining hypotheses regarding the benefits of their activation in memory disorders at the hippocampal level.
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Déjà-vu? Neural and behavioural effects of the 5-HT 4 receptor agonist, prucalopride, in a hippocampal-dependent memory task. Transl Psychiatry 2021; 11:497. [PMID: 34602607 PMCID: PMC8488034 DOI: 10.1038/s41398-021-01568-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/04/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022] Open
Abstract
Cognitive deficits commonly accompany psychiatric disorders but are often underrecognised, and difficult to treat. The 5-HT4 receptor is a promising potential treatment target for cognitive impairment because in animal studies 5-HT4 receptor agonists enhance hippocampal-dependent memory processes. To date, there has been little work translating these effects to humans. We tested whether short-term administration of the 5-HT4 partial agonist, prucalopride, modified behavioural and neural (fMRI) memory processing in 44 healthy human volunteers using an experimental medicine model. We found that participants who had received six days of prucalopride treatment were significantly better at recalling previously seen neutral images and distinguishing them from new images. At a neural level, prucalopride bilaterally increased hippocampal activity and activity in the right angular gyrus compared with placebo. Taken together, these findings demonstrate the potential of 5-HT4-receptor activation for cognitive enhancement in humans, and support the potential of this receptor as a treatment target for cognitive impairment.
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Nirogi R, Mohammed AR, Shinde AK, Gagginapally SR, Kancharla DM, Ravella SR, Bogaraju N, Middekadi VR, Subramanian R, Palacharla RC, Benade V, Muddana N, Abraham R, Medapati RB, Thentu JB, Mekala VR, Petlu S, Lingavarapu BB, Yarra S, Kagita N, Goyal VK, Pandey SK, Jasti V. Discovery and Preclinical Characterization of Usmarapride (SUVN-D4010): A Potent, Selective 5-HT 4 Receptor Partial Agonist for the Treatment of Cognitive Deficits Associated with Alzheimer's Disease. J Med Chem 2021; 64:10641-10665. [PMID: 34251799 DOI: 10.1021/acs.jmedchem.1c00703] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of oxadiazole derivatives were synthesized and evaluated as 5-hydroxytryptamine-4 receptor (5-HT4R) partial agonists for the treatment of cognitive deficits associated with Alzheimer's disease. Starting from a reported 5-HT4R antagonist, a systematic structure-activity relationship was conducted, which led to the discovery of potent and selective 5-HT4R partial agonist 1-isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole oxalate (Usmarapride, 12l). It showed balanced physicochemical-pharmacokinetic properties with robust nonclinical efficacy in cognition models. It also showed disease-modifying potential, as it increased neuroprotective soluble amyloid precursor protein alpha levels, and dose-dependent target engagement and correlation of efficacy with oral exposures. Phase 1 clinical studies have been completed and projected efficacious concentration was achieved without any major safety concerns. Phase 2 enabling long-term safety studies have been completed with no concerns for further development.
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Affiliation(s)
- Ramakrishna Nirogi
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Abdul Rasheed Mohammed
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Anil Karbhari Shinde
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | | | | | - Srinivasa Rao Ravella
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Narsimha Bogaraju
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Vanaja Reddy Middekadi
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Ramkumar Subramanian
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | | | - Vijay Benade
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Nageswararao Muddana
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Renny Abraham
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Rajesh Babu Medapati
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Jagadeesh Babu Thentu
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Venkat Reddy Mekala
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Surendra Petlu
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Bujji Babu Lingavarapu
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Sivasekhar Yarra
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Narendra Kagita
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Vinod Kumar Goyal
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Santosh Kumar Pandey
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
| | - Venkat Jasti
- Suven Life Sciences Limited, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad 500 034, India
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Understanding the Molecular Basis of 5-HT 4 Receptor Partial Agonists through 3D-QSAR Studies. Int J Mol Sci 2021; 22:ijms22073602. [PMID: 33808456 PMCID: PMC8036435 DOI: 10.3390/ijms22073602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 12/15/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder whose prevalence has an incidence in senior citizens. Unfortunately, current pharmacotherapy only offers symptom relief for patients with side effects such as bradycardia, nausea, and vomiting. Therefore, there is a present need to provide other therapeutic alternatives for treatments for these disorders. The 5-HT4 receptor is an attractive therapeutic target since it has a potential role in central and peripheral nervous system disorders such as AD, irritable bowel syndrome, and gastroparesis. Quantitative structure-activity relationship analysis of a series of 62 active compounds in the 5-HT4 receptor was carried out in the present work. The structure-activity relationship was estimated using three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques based on these structures' field molecular (force and Gaussian field). The best force-field QSAR models achieve a value for the coefficient of determination of the training set of R2training = 0.821, and for the test set R2test = 0.667, while for Gaussian-field QSAR the training and the test were R2training = 0.898 and R2test = 0.695, respectively. The obtained results were validated using a coefficient of correlation of the leave-one-out cross-validation of Q2LOO = 0.804 and Q2LOO = 0.886 for force- and Gaussian-field QSAR, respectively. Based on these results, novel 5-HT4 partial agonists with potential biological activity (pEC50 8.209-9.417 for force-field QSAR and 9.111-9.856 for Gaussian-field QSAR) were designed. In addition, for the new analogues, their absorption, distribution, metabolism, excretion, and toxicity properties were also analyzed. The results show that these new derivatives also have reasonable pharmacokinetics and drug-like properties. Our findings suggest novel routes for the design and development of new 5-HT4 partial agonists.
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Wang N, Qiu P, Cui W, Yan X, Zhang B, He S. Recent Advances in Multi-target Anti-Alzheimer Disease Compounds (2013 Up to the Present). Curr Med Chem 2019; 26:5684-5710. [DOI: 10.2174/0929867326666181203124102] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 08/03/2018] [Accepted: 11/03/2018] [Indexed: 12/21/2022]
Abstract
:
Since the last century, when scientists proposed the lock-and-key model, the discovery of
drugs has focused on the development of drugs acting on single target. However, single-target drug
therapies are not effective to complex diseases with multi-factorial pathogenesis. Moreover, the
combination of single-target drugs readily causes drug resistance and side effects. In recent years,
multi-target drugs have increasingly been represented among FDA-approved drugs. Alzheimer’s
Disease (AD) is a complex and multi-factorial disease for which the precise molecular mechanisms
are still not fully understood. In recent years, rational multi-target drug design methods, which combine
the pharmacophores of multiple drugs, have been increasingly applied in the development of
anti-AD drugs. In this review, we give a brief description of the pathogenesis of AD and provide
detailed discussions about the recent development of chemical structures of anti-AD agents (2013 up
to present) that have multiple targets, such as amyloid-β peptide, Tau protein, cholinesterases,
monoamine oxidase, β-site amyloid-precursor protein-cleaving enzyme 1, free radicals, metal ions
(Fe2+, Cu2+, Zn2+) and so on. In this paper, we also added some novel targets or possible pathogenesis
which have been reported in recent years for AD therapy. We hope that these findings may provide
new perspectives for the pharmacological treatment of AD.
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Affiliation(s)
- Ning Wang
- Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Research Center, Ningbo University, Ningbo 315211, China
| | - Panpan Qiu
- Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Research Center, Ningbo University, Ningbo 315211, China
| | - Wei Cui
- Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Research Center, Ningbo University, Ningbo 315211, China
| | - Xiaojun Yan
- Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Research Center, Ningbo University, Ningbo 315211, China
| | - Bin Zhang
- Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Research Center, Ningbo University, Ningbo 315211, China
| | - Shan He
- Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Research Center, Ningbo University, Ningbo 315211, China
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Targeting phosphocreatine metabolism in relapsing-remitting multiple sclerosis: evaluation with brain MRI, 1H and 31P MRS, and clinical and cognitive testing. J Neurol 2018; 265:2614-2624. [PMID: 30187159 DOI: 10.1007/s00415-018-9039-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND/OBJECTIVES Fluoxetine and prucalopride might change phosphocreatine (PCr) levels via the cAMP-PKA pathway, an interesting target in the neurodegenerative mechanisms of MS. METHODS We conducted a two-center double-blind, placebo-controlled, randomized trial including 48 relapsing-remitting MS patients. Patients were randomized to receive placebo (n = 13), fluoxetine (n = 15), or prucalopride (n = 14) for 6 weeks. Proton (1H) and phosphorus (31P) magnetic resonance spectroscopy (MRS) as well as volumetric and perfusion MR imaging were performed at weeks 0, 2, and 6. Clinical and cognitive testing were evaluated at weeks 0 and 6. RESULTS No significant changes were observed for both 31P and 1H MRS indices. We found a significant effect on white matter volume and a trend towards an increase in grey matter and whole brain volume in the fluoxetine group at week 2; however, these effects were not sustained at week 6 for white matter and whole brain volume. Fluoxetine and prucalopride showed a positive effect on 9-HPT, depression, and fatigue scores. CONCLUSION Both fluoxetine and prucalopride had a symptomatic effect on upper limb function, fatigue, and depression, but this should be interpreted with caution. No effect of treatment was found on 31P and 1H MRS parameters, suggesting that these molecules do not influence the PCr metabolism.
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Lo AC, De Maeyer JH, Vermaercke B, Callaerts-Vegh Z, Schuurkes JAJ, D'Hooge R. SSP-002392, a new 5-HT4 receptor agonist, dose-dependently reverses scopolamine-induced learning and memory impairments in C57Bl/6 mice. Neuropharmacology 2014; 85:178-89. [PMID: 24863046 DOI: 10.1016/j.neuropharm.2014.05.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 05/09/2014] [Accepted: 05/10/2014] [Indexed: 10/25/2022]
Abstract
5-HT4 receptors (5-HT4R) are suggested to affect learning and memory processes. Earlier studies have shown that animals treated with 5-HT4R agonists, often with limited selectivity, show improved learning and memory with retention memory often being assessed immediately after or within 24 h after the last training session. In this study, we characterized the effect of pre-training treatment with the selective 5-HT4R agonist SSP-002392 on memory acquisition and the associated long-term memory retrieval in animal models of impaired cognition. Pre-training treatment with SSP-002392 (0.3 mg/kg, 1.5 mg/kg and 7.5 mg/kg p.o.) dose-dependently inhibited the cognitive deficits induced by scopolamine (0.5 mg/kg s.c.) in two different behavioral tasks: passive avoidance and Morris water maze. In the Morris water maze, spatial learning was significantly improved after treatment with SSP-002392 translating in an accelerated and more efficient localization of the hidden platform compared to scopolamine-treated controls. Moreover, retention memory was assessed 24 h (passive avoidance) and 72 h (Morris water maze) after the last training session of cognitive-impaired animals and this was significantly improved in animals treated with SSP-002392 prior to the training sessions. Furthermore, the effects of SSP-002392 were comparable to galanthamine hydrobromide. We conclude that SSP-002392 has potential as a memory-enhancing compound.
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Affiliation(s)
- Adrian C Lo
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Leuven, Belgium
| | | | - Ben Vermaercke
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Leuven, Belgium
| | - Zsuzsanna Callaerts-Vegh
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Leuven, Belgium
| | | | - Rudi D'Hooge
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Leuven, Belgium.
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8
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Regulation of amyloid precursor protein processing by serotonin signaling. PLoS One 2014; 9:e87014. [PMID: 24466315 PMCID: PMC3897773 DOI: 10.1371/journal.pone.0087014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 12/16/2013] [Indexed: 11/25/2022] Open
Abstract
Proteolytic processing of the amyloid precursor protein (APP) by the β- and γ-secretases releases the amyloid-β peptide (Aβ), which deposits in senile plaques and contributes to the etiology of Alzheimer's disease (AD). The α-secretase cleaves APP in the Aβ peptide sequence to generate soluble APPα (sAPPα). Upregulation of α-secretase activity through the 5-hydroxytryptamine 4 (5-HT4) receptor has been shown to reduce Aβ production, amyloid plaque load and to improve cognitive impairment in transgenic mouse models of AD. Consequently, activation of 5-HT4 receptors following agonist stimulation is considered to be a therapeutic strategy for AD treatment; however, the signaling cascade involved in 5-HT4 receptor-stimulated proteolysis of APP remains to be determined. Here we used chemical and siRNA inhibition to identify the proteins which mediate 5-HT4d receptor-stimulated α-secretase activity in the SH-SY5Y human neuronal cell line. We show that G protein and Src dependent activation of phospholipase C are required for α-secretase activity, while, unexpectedly, adenylyl cyclase and cAMP are not involved. Further elucidation of the signaling pathway indicates that inositol triphosphate phosphorylation and casein kinase 2 activation is also a prerequisite for α-secretase activity. Our findings provide a novel route to explore the treatment of AD through 5-HT4 receptor-induced α-secretase activation.
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9
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In-vitro acetylcholine release is not a straightforward model to study hippocampal 5-HT4 receptors. Neuroreport 2011; 22:892-6. [DOI: 10.1097/wnr.0b013e32834c7fd4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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10
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Terry AV, Callahan PM, Hall B, Webster SJ. Alzheimer's disease and age-related memory decline (preclinical). Pharmacol Biochem Behav 2011; 99:190-210. [PMID: 21315756 DOI: 10.1016/j.pbb.2011.02.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 01/21/2011] [Accepted: 02/01/2011] [Indexed: 01/05/2023]
Abstract
An unfortunate result of the rapid rise in geriatric populations worldwide is the increasing prevalence of age-related cognitive disorders such as Alzheimer's disease (AD). AD is a devastating neurodegenerative illness that is characterized by a profound impairment of cognitive function, marked physical disability, and an enormous economic burden on the afflicted individual, caregivers, and society in general. The rise in elderly populations is also resulting in an increase in individuals with related (potentially treatable) conditions such as "Mild Cognitive Impairment" (MCI) which is characterized by a less severe (but abnormal) level of cognitive impairment and a high-risk for developing dementia. Even in the absence of a diagnosable disorder of cognition (e.g., AD and MCI), the perception of increased forgetfulness and declining mental function is a clear source of apprehension in the elderly. This is a valid concern given that even a modest impairment of cognitive function is likely to be associated with significant disability in a rapidly evolving, technology-based society. Unfortunately, the currently available therapies designed to improve cognition (i.e., for AD and other forms of dementia) are limited by modest efficacy and adverse side effects, and their effects on cognitive function are not sustained over time. Accordingly, it is incumbent on the scientific community to develop safer and more effective therapies that improve and/or sustain cognitive function in the elderly allowing them to remain mentally active and productive for as long as possible. As diagnostic criteria for memory disorders evolve, the demand for pro-cognitive therapeutic agents is likely to surpass AD and dementia to include MCI and potentially even less severe forms of memory decline. The purpose of this review is to provide an overview of the contemporary therapeutic targets and preclinical pharmacologic approaches (with representative drug examples) designed to enhance memory function.
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Affiliation(s)
- Alvin V Terry
- Department of Pharmacology and Toxicology and Small Animal Behavior Core, Medical College of Georgia, Augusta, GA 30912, USA.
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Investigation into the efficacy of the acetylcholinesterase inhibitor, donepezil, and novel procognitive agents to induce gamma oscillations in rat hippocampal slices. Neuropharmacology 2010; 59:437-43. [DOI: 10.1016/j.neuropharm.2010.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 06/04/2010] [Accepted: 06/10/2010] [Indexed: 11/17/2022]
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12
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Randall AD, Witton J, Booth C, Hynes-Allen A, Brown JT. The functional neurophysiology of the amyloid precursor protein (APP) processing pathway. Neuropharmacology 2010; 59:243-67. [PMID: 20167227 DOI: 10.1016/j.neuropharm.2010.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Amyloid beta (Abeta) peptides derived from proteolytic cleavage of amyloid precursor protein (APP) are thought to be a pivotal toxic species in the pathogenesis of Alzheimer's disease (AD). Furthermore, evidence has been accumulating that components of APP processing pathway are involved in non-pathological normal function of the CNS. In this review we aim to cover the extensive body of research aimed at understanding how components of this pathway contribute to neurophysiological function of the CNS in health and disease. We briefly outline changes to clinical neurophysiology seen in AD patients before discussing functional changes in mouse models of AD which range from changes to basal synaptic transmission and synaptic plasticity through to abnormal synchronous network activity. We then describe the various neurophysiological actions that are produced by application of exogenous Abeta in various forms, and finally discuss a number or other neurophysiological aspects of the APP pathway, including functional activities of components of secretase complexes other than Abeta production.
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Affiliation(s)
- A D Randall
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol School of Medical Sciences, Bristol, UK.
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Abstract
With the aging of the population, the incidence and prevalence of Alzheimer's disease will grow, increasing the burden on individuals and society. While ameliorating symptoms, the currently available treatments approved by the US Food and Drug Administration do not halt progression or cure the illness. This article discusses recent data on treatment strategies targeting amyloid and tau pathology. Novel therapeutic strategies such as inhibitors of receptors for advanced glycation end products (RAGE), potential mitochondrial modification with Dimebon, anti-inflammatory approaches, and cholesterol-lowering agents are also reviewed. An update on results from pharmacologic and nonpharmacologic prevention trials is provided.
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De Maeyer JH, Schuurkes JAJ, Lefebvre RA. Selective desensitization of the 5-HT4 receptor-mediated response in pig atrium but not in stomach. Br J Pharmacol 2009; 156:362-76. [PMID: 19154432 DOI: 10.1111/j.1476-5381.2008.00007.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The time dependency of the effect of 5-HT(4) receptor agonists depends on many specific regulatory mechanisms, which vary between tissues. This has important implications with regard to the effects of endogenous 5-HT, as well as to the clinical use of 5-HT(4) receptor agonists, and might contribute to tissue selectivity of agonists. EXPERIMENTAL APPROACH The progression and desensitization of 5-HT(4) receptor-mediated responses were evaluated in an organ bath set-up using two, clinically relevant, porcine in vitro models: gastric cholinergic neurotransmission and atrial contractility. KEY RESULTS Exposure of gastric tissue to 5-HT or to the selective 5-HT(4) receptor agonists prucalopride and M0003 results in a sustained non-transient effect during exposure; after washout, the response to a subsequent challenge with 5-HT shows no clear desensitization. Incubation of left atrial tissue with 5-HT resulted in a transient response, leading after washout to a marked desensitization of the subsequent response to 5-HT. The selective 5-HT(4) receptor agonists prucalopride and M0003 induce only very weak atrial responses whereas they are very effective in desensitizing the atrial response to 5-HT. The observations also suggest that the properties of prucalopride and M0003 to bind to and/or activate the 5-HT(4) receptor differ from those of 5-HT. This difference might have contributed to the observed desensitization. CONCLUSIONS AND IMPLICATIONS The high potency of prucalopride and M0003 in desensitizing the response to 5-HT together with their low efficacy in the atrium emphasizes the cardiac safety of this class of 5-HT(4) receptor agonists.
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Affiliation(s)
- J H De Maeyer
- Heymans Institute of Pharmacology, Ghent University, Ghent, Belgium.
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15
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Ray AM, Kelsell RE, Houp JA, Kelly FM, Medhurst AD, Cox HM, Calver AR. Identification of a novel 5-HT(4) receptor splice variant (r5-HT(4c1)) and preliminary characterisation of specific 5-HT(4a) and 5-HT(4b) receptor antibodies. Eur J Pharmacol 2008; 604:1-11. [PMID: 19100256 DOI: 10.1016/j.ejphar.2008.11.056] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 11/24/2008] [Accepted: 11/25/2008] [Indexed: 01/08/2023]
Abstract
The human 5-hydroxytryptamine (5-HT(4)) receptor is encoded by a highly complex gene which gives rise to at least 10 distinct splice variants. However, the functional relevance of these variants is unknown. In rat, only three such variants have been identified, 5-HT(4a) (r5-HT(4a)), 5-HT(4b) (r5-HT(4b)) and 5-HT(4e) (r5-HT(4e)). In the current study we identify and characterise the pharmacology of a novel rat splice variant (r5-HT(4c1)) and present the first comprehensive analysis of 5-HT(4) splice variant mRNA expression levels throughout the rat gastrointestinal tract. In addition, we describe preliminary characterisation of the first 5-HT(4) splice variant specific antibodies. In transfected cells, r5-HT(4c1) receptor exhibited similar binding properties to r5-HT(4a) and r5-HT(4b). Functional studies showed that 5-HT(4) agonists prucalopride (4-amino-5-chloro-2,3-dihydro-N-[1-(3-methoxypropyl)-4-piperidinyl]-7-benzofuran carboxamide monohydrochloride and renzapride (+/-)-endo-4-amino-5-chloro-2-methoxy-N-(1-azabicyclo[3.3.1]non-4-yl)benzamide monohydrochloride) acted as partial agonists at r5-HT(4c1), but full agonists at r5-HT(4a) and r5-HT(4b). Moreover, in contrast to r5-HT(4a) and r5-HT(4b), r5-HT(4c1) was not constitutively active. TaqMan mRNA analysis showed that r5-HT(4a) expression in brain and dorsal root ganglion exceeded that in the gastrointestinal tract, whilst the reverse was true for r5-HT(4b) and r5-HT(4c1). mRNA expression of each variant also increased distally throughout the gastrointestinal tract with the highest levels in the colon. r5-HT(4a) and r5-HT(4b) specific immunoreactivity was abundant on enteric neurons in jejunum, ileum and colon as well as neurons and satellite cells of the dorsal root ganglion. Only r5-HT(4b) immunoreactivity was observed on endocrine cells in the duodenum. These data could have implications in rat models and aid understanding of 5-HT(4) splice variant function.
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Affiliation(s)
- Alison M Ray
- Neuroscience Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, UK.
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Restivo L, Roman F, Dumuis A, Bockaert J, Marchetti E, Ammassari-Teule M. The promnesic effect of G-protein-coupled 5-HT4 receptors activation is mediated by a potentiation of learning-induced spine growth in the mouse hippocampus. Neuropsychopharmacology 2008; 33:2427-34. [PMID: 18075492 DOI: 10.1038/sj.npp.1301644] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pharmacological modulation of synaptic efficacy is a prominent target in the identification of promnesic compounds. Here, we report that pretraining administration of the serotonin 5-HT(4) receptors (5-HT(4)Rs) partial agonist SL65.0155 enhances simultaneous olfactory discrimination performance and potentiates learning-induced dendritic spine growth in the mouse hippocampus. SL65.0155 does not affect spine density in the pseudo-trained mice and, by itself, does not promote spine growth. Injecting the 5-HT(4) antagonist RS39604 prior to SL65.0155 prevents both the increase in performance and the additional formation of spines, thus confirming the 5-HT(4)Rs specificity of the observed effects. These findings provide evidence that 5-HT(4)Rs stimulation selectively increases experience-dependent structural plasticity in learning-activated hippocampal circuits.
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Korol TY, Korol SV, Kostyuk EP, Kostyuk PG. β-amyloid-induced changes in calcium homeostasis in cultured hippocampal neurons of the rat. NEUROPHYSIOLOGY+ 2008. [DOI: 10.1007/s11062-008-9013-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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Marchetti E, Jacquet M, Jeltsch H, Migliorati M, Nivet E, Cassel JC, Roman FS. Complete recovery of olfactory associative learning by activation of 5-HT4 receptors after dentate granule cell damage in rats. Neurobiol Learn Mem 2008; 90:185-91. [PMID: 18485752 DOI: 10.1016/j.nlm.2008.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Revised: 03/31/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
Abstract
Bilateral intradentate injections of 3.0microg of colchicine induced a substantial loss of granule cells and damage to the overlying pyramidal cell layer in region CA1 in adult male Long-Evans rats. All rats with such lesions showed a significant associative learning deficit in an olfactory discrimination task, while being unimpaired in the procedural component of this task. Injection of a partial selective 5-HT(4) agonist (SL65.0155; 0.01mg/kg, i.p., vs. saline) before the third of six training sessions enabled complete recovery of associative learning performance in the lesioned rats. Activation of 5-HT(4) receptors by a selective agonist such as SL65.0155 might therefore provide an opportunity to reduce learning and memory deficits associated with temporal lobe damage, and could be useful for the symptomatic treatment of memory dysfunctions related to pathological aging such as Alzheimer's disease.
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Affiliation(s)
- E Marchetti
- Laboratoire de Neurobiologie des Processus Mnésiques, UMR 6149 CNRS Université de Provence, IFR 131 des Neurosciences et GDR 2905 du CNRS, Centre St. Charles, Pôle 3 C-3, Place Victor Hugo, 13331 Marseille Cedex 03, France
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19
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Lezoualc'h F. 5-HT4 receptor and Alzheimer's disease: The amyloid connection. Exp Neurol 2007; 205:325-9. [PMID: 17346704 DOI: 10.1016/j.expneurol.2007.02.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 01/30/2007] [Accepted: 02/01/2007] [Indexed: 11/21/2022]
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20
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Huang YY, Kandel ER. 5-Hydroxytryptamine induces a protein kinase A/mitogen-activated protein kinase-mediated and macromolecular synthesis-dependent late phase of long-term potentiation in the amygdala. J Neurosci 2007; 27:3111-9. [PMID: 17376972 PMCID: PMC6672482 DOI: 10.1523/jneurosci.3908-06.2007] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The amygdala is a critical site for the acquisition of learned fear memory in mammals, and the formation and long-term maintenance of fear memories are thought to be associated with changes of synaptic strength in the amygdala. Here we report that serotonin (5-hydroxytryptamine; 5-HT), a modulatory neurotransmitter known to be linked to learned fearful and emotional behavior, has dual effects on excitatory synaptic transmission in the basolateral amygdala. There is an early depression of synaptic transmission lasting 30-50 min, mediated by 5-HT1A, and a late, long-lasting facilitation lasting >5 h in slice recordings, mediated by the 5-HT4 receptor. 5-HT late phase long-term potentiation (L-LTP) is blocked by inhibitors of either protein kinase A (PKA) and/or mitogen-activated kinase (MAPK) and requires new protein synthesis and gene transcription. Moreover, the 5-HT-induced L-LTP in neurons of amygdala is blocked by the actin inhibitor cytochalasin D, suggesting that 5-HT stimulates a cytoskeletal rearrangement. These results show, for the first time, that 5-HT can produce long-lasting facilitation of synaptic transmission in the amygdala and provides evidence for the possible synaptic role of 5-HT in long-term memory for learned fear.
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Affiliation(s)
- Yan-You Huang
- Center for Neurobiology and Behavior of the College of Physicians and Surgeons of Columbia University
| | - Eric R. Kandel
- Kavli Institute for Brain Science
- Center for Neurobiology and Behavior of the College of Physicians and Surgeons of Columbia University
- New York State Psychiatric Institute, and
- Howard Hughes Medical Institute, Columbia University, New York, New York 10032
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Cachard-Chastel M, Lezoualc'h F, Dewachter I, Deloménie C, Croes S, Devijver H, Langlois M, Van Leuven F, Sicsic S, Gardier AM. 5-HT4 receptor agonists increase sAPPalpha levels in the cortex and hippocampus of male C57BL/6j mice. Br J Pharmacol 2007; 150:883-92. [PMID: 17325649 PMCID: PMC2013878 DOI: 10.1038/sj.bjp.0707178] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE A strategy to treat Alzheimer's disease (AD) is to increase the soluble form of amyloid precursor protein (sAPPalpha), a promnesic protein, in the brain. Because strong evidence supports beneficial effects of 5-hydroxytryptamine 5-HT(4) receptor agonists in memory and learning, we investigated the role of 5-HT(4) receptors on APP processing in 8 weeks-old male C57BL/6j mice. EXPERIMENTAL APPROACH Mice were given, subcutaneously, prucalopride or ML 10302 (s.c.), two highly selective 5-HT(4) receptor agonists and, up to 240 min later, the hippocampus and cortex were analysed by Western blot for sAPPalpha determination. KEY RESULTS Prucalopride (5 or 10 mg kg(-1)) significantly increased sAPPalpha levels in the hippocampus and cortex, but did not modify the expression level of APP mRNA as detected by quantitative RT-PCR. A selective 5-HT(4) receptor antagonist, GR125487 (1 mg kg(-1), s.c.) inhibited prucalopride induced- increase in sAPPalpha levels. In addition, levels of sAPPalpha were increased by ML10302 only at 20 mg kg(-1) and was limited to the cortex. Also, prucalopride increased sAPPalpha levels in the cortex of a transgenic mouse model of AD, expressing the London mutation of APP. Furthermore, the combined injection of a selective acetylcholinesterase inhibitor, donepezil and prucalopride induced a synergic increase in sAPPalpha levels in the cortex and hippocampus. CONCLUSIONS AND IMPLICATIONS Our results demonstrate that the 5-HT(4) receptor plays a key role in the non-amyloidogenic pathway of APP metabolism in vivo and give support to the beneficial use of 5-HT(4) agonists for AD treatment.
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Affiliation(s)
- M Cachard-Chastel
- EA3544, Sérotonine et Neuropharmacologie, Faculté de Pharmacie, Universite Paris-Sud Châtenay-Malabry cedex, France
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - F Lezoualc'h
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
- INSERM, U769, Signalisation et Physiopathologie Cardiaque, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - I Dewachter
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - C Deloménie
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - S Croes
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - H Devijver
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - M Langlois
- BIOCIS, Laboratoire de Reconnaissance Moléculaire et Synthèse, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - F Van Leuven
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - S Sicsic
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
- BIOCIS, Laboratoire de Reconnaissance Moléculaire et Synthèse, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - A M Gardier
- EA3544, Sérotonine et Neuropharmacologie, Faculté de Pharmacie, Universite Paris-Sud Châtenay-Malabry cedex, France
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
- Author for correspondence:
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Scatena R, Martorana GE, Bottoni P, Botta G, Pastore P, Giardina B. An update on pharmacological approaches to neurodegenerative diseases. Expert Opin Investig Drugs 2007; 16:59-72. [PMID: 17155854 DOI: 10.1517/13543784.16.1.59] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Neurodegenerative diseases are now generally considered as a group of disorders that seriously and progressively impair the functions of the nervous system through selective neuronal vulnerability of specific brain regions. Alzheimer's disease is the most common neurodegenerative disease, followed in incidence by Parkinson's disease; much less common are frontotemporal dementia, Huntington's disease, amyothrophic lateral sclerosis (Lou Gehrig's disease), progressive supranuclear palsy, spinocerebellar ataxia, Pick's disease and, lastly, prion disease. In this review, the authors intend to survey new drugs in different clinical phases but not in the preclinical or discovery stages nor already in the market, with new molecules aimed at interrupting or at attenuating different pathogenic pathways of neurodegeneration and/or at ameliorating symptoms. Drugs in different pharmacological phases are under study or are ready to be introduced into therapy for Alzheimer's disease, which display anti-beta-amyloid activity or nerve growth factor-like activity or anti-inflammatory properties. Other drugs possess mixed mechanisms of action, such as acetylcholinesterase inhibition and impairment of beta-amyloid formation through inhibition of beta-amyloid precursor protein synthesis and/or modulation of secretase activity. Other therapeutic approaches are based on immunotherapy, control of metal ions interactions with beta-amyloid and ensuing oxidative reactions as well as metabolic or hormonal regulation. The symptomatic therapy of motor behaviour in Parkinson's disease, based on l-DOPA, is registering adenosine A(2A) receptor antagonists, monoamine oxidase B inhibitors and ion channel modulators, as well as dopamine uptake inhibitors and glutamate AMPA receptor antagonists. There are also many other drugs involved, including astrocyte-modulating agents, 5-HT(1A) agonists and alpha(2)-adrenergic receptor antagonists, which are targeted at preventing or ameliorating Parkinson's disease-related or l-DOPA-induced dyskinesias. Huntington's disease therapy envisages a Phase III drug, LAX-101, which displays antiapoptotic properties by promoting membrane stabilisation and mitochondrial integrity. Other drugs with antioxidant and antiapoptotic steroid-like and neuroprotective activity are under investigation for the therapy of the less common neurodegenerative diseases.
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Affiliation(s)
- Roberto Scatena
- Istituto di Biochimica e Biochimica Clinica, Universita' Cattolica del Sacro Cuore, Largo A. Gemelli 8, 00168 Rome, Italy.
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Micale V, Leggio GM, Mazzola C, Drago F. Cognitive effects of SL65.0155, a serotonin 5-HT4 receptor partial agonist, in animal models of amnesia. Brain Res 2006; 1121:207-15. [PMID: 17011531 DOI: 10.1016/j.brainres.2006.08.108] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 08/27/2006] [Accepted: 08/29/2006] [Indexed: 11/19/2022]
Abstract
Given that several data suggest the involvement of serotonergic (5-HT) system, particularly the serotonin 5-HT(4) receptors, in memory processes; this study was undertaken to investigate the role of serotonin 5-HT(4) receptors in different experimental models of amnesia in male Swiss mice or in male Sprague-Dawley rats, tested in learning and memory tasks. Amnesia was induced in mice by intracerebroventricular (i.c.v.) injection of beta-amyloid 1-42 fragment (BAP 1-42; 400 pmol/mouse) or of galanin (GAL) 1-29 (3 microg/mouse). Another group of animals was exposed to carbon monoxide (CO). Treatments were made 14 days, 15 min or 8 days prior to the learning trial of a step-through passive avoidance paradigm, respectively. Latency to re-enter the dark box appeared to be reduced in all treatment groups. Intraperitoneal (i.p.) administration of SL65.0155 (5-(8-amino-7-chloro-2,3-dihydro-1,4-benzodioxin-5-yl)-3-[1-(2-phenylethyl)-4-piperidinyl]-1,3,4-oxadiazol-2(3H)-one-monohydrochloride), a serotonin 5-HT(4) receptor partial agonist (1 mg/kg/day), for 7 days prior to the learning trial, inhibited the amnesic effect of both peptides increasing the latency to re-enter the dark box also in mice exposed to CO. In rats with ibotenate-induced lesions of the nucleus basalis magnocellularis (NBM) or prenatally exposed to methylazoxymethanol (MAM), SL65.0155 (1 mg/kg/day, i.p.) administered for 7 days, improved the learning and memory capacity in animals tested in shuttle-box active avoidance and radial maze tests. These findings give further support to the hypothesis of SL65.0155 cognition-enhancing activity across a range of tasks.
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Affiliation(s)
- Vincenzo Micale
- Department of Experimental and Clinical Pharmacology, University of Catania, Viale A. Doria, 6, 95125 Catania, Italy
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Mlinar B, Mascalchi S, Mannaioni G, Morini R, Corradetti R. 5‐HT4 receptor activation induces long‐lasting EPSP‐spike potentiation in CA1 pyramidal neurons. Eur J Neurosci 2006; 24:719-31. [PMID: 16930402 DOI: 10.1111/j.1460-9568.2006.04949.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent studies implicated involvement of the 5-hydroxytryptamine4 (5-HT4) receptor in cognitive and emotional processes. The highest 5-HT4 receptor densities in the brain are found in the limbic system including the hippocampus. Here we used the selective 5-HT4 receptor full agonist, N-pentyl-N'-aminoguanidine carbazimidamide (SDZ-216454) to characterize effects of 5-HT4 receptor activation in whole-cell and field recordings in the area CA1 in hippocampal slices prepared from 3 to 4- and 6 to 9-week-old rats, respectively. Extracellular recordings showed that transient 5-HT4 receptor activation by 10-20 min application of SDZ-216454 induces field excitatory postsynaptic potential (fEPSP)-population spike potentiation (ESP(5-HT4)), which persisted for as long as we held the recordings (> 2 h). ESP(5-HT4) displayed characteristics different from EPSP-spike potentiation that accompanies long-term potentiation; it developed without an associated increase in synaptic transmission, was independent on afferent input, activity of postsynaptic neurons and N-methyl-d-aspartate receptor activation; and was expressed in the presence of GABA receptor antagonists. ESP(5-HT4) was also induced by transient application of the natural neurotransmitter, 5-HT. The increase in the evoked population spike (PS) induced by SDZ-216454 was not prevented by blockers of hyperpolarization-activated cation current (Ih), Cs+ and ZD-7288, but was mimicked and occluded by 150 microm Ba2+. Whole-cell voltage-clamp recordings from pyramidal neurons demonstrated that SDZ-216454 application increases membrane resistance with a concomitant decrease in a Ba2+-sensitive inwardly rectifying K+ current and the Ba2+-insensitive K+ current underlying slow afterhyperpolarization (I(sAHP)). We conclude that 5-HT4 receptor activation may cause a long-lasting excitability increase in CA1 pyramidal neurons by inhibition of a Ba2+-sensitive inwardly rectifying K+ current.
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Affiliation(s)
- Boris Mlinar
- Department of Preclinical and Clinical Pharmacology Mario Aiazzi-Mancini University of Florence, Viale G. Pieraccini 6, 50139 Florence, Italy.
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Spencer JP, Weil A, Hill K, Hussain I, Richardson JC, Cusdin FS, Chen YH, Randall AD. Transgenic mice over-expressing human beta-amyloid have functional nicotinic alpha 7 receptors. Neuroscience 2005; 137:795-805. [PMID: 16303255 DOI: 10.1016/j.neuroscience.2005.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 09/29/2005] [Accepted: 10/07/2005] [Indexed: 11/22/2022]
Abstract
A potentially major factor in the development of Alzheimer's disease is the enhanced production of soluble beta-amyloid peptide fragments amyloid beta peptide(1-40) and amyloid beta peptide(1-42). These amyloid peptides are generated by cleavage of the amyloid-precursor protein and aggregate spontaneously to form amyloid plaques, which are a classical pathological hallmark in Alzheimer's disease. Although the precise mechanisms are unknown, it is widely believed that amyloid peptides initiate the degenerative process, resulting in subsequent cognitive decline. One interaction of amyloid beta peptide that may contribute to an impairment of cognition is its high affinity binding to the alpha 7 nicotinic receptor; a receptor shown to be important for cognition in a number of studies. There is some controversy, however, whether amyloid beta peptide inhibits or activates this receptor. We have cloned and stably expressed the human alpha 7 receptor and investigated its interaction with amyloid beta peptide using patch clamp electrophysiology. Human alpha 7 was activated in a concentration-dependent fashion by nicotine, acetylcholine and choline and potently inhibited by methyllycaconitine citrate. The responses were inwardly rectifying and exhibited rapid activation, desensitization and deactivation. Amyloid beta peptide(1-42) antagonized human alpha7 responses in a partially reversible fashion; no agonist effects of amyloid beta peptide(1-42) were detected. A similar inhibition of mouse alpha 7 was also observed. In addition, we have assessed the function of native alpha 7 receptors in hippocampal slices prepared from transgenic mice that over-express human amyloid. Despite this clear inhibition of recombinant receptors, hippocampal GABAergic interneurones in slices from beta-amyloid over-expressing mice still possess alpha 7 receptor-mediated currents.
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Affiliation(s)
- J P Spencer
- Neurology and GI CEDD, GlaxoSmithKline, Harlow, Essex CM19 5AW, UK.
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26
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Recent Advances in Selective Serotonergic Agents. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2005. [DOI: 10.1016/s0065-7743(05)40002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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