Nuestros investigadores

Ana María García Osta

Neurobiología del Alzheimer
Neurociencias. Fundación para la Investigación Médica Aplicada
Líneas de investigación
Estudio de las bases moleculares de la demencia asociada a la enfermedad de Alzheimer en modelos animales. Identificacion de nuevas dianas terapeuticas para el tratamiento de la enfermedad de Alzheimer.
Índice H
22, (WoS, 22/10/2019)
24, (Scopus, 22/10/2019)

Publicaciones científicas más recientes (desde 2010)

Autores: Gil Iturbe, Eva; Solas Zubiaurre, Maite; Cuadrado Tejedor, María del Mar; et al.
ISSN 0893-7648  Vol. 57  Nº 2  2020  págs. 798 - 805
The brain depends on glucose as a source of energy. This implies the presence of glucose transporters, being GLUT1 and GLUT3 the most relevant. Expression of GLUT12 is found in mouse and human brain at low levels. We previously demonstrated GLUT12 upregulation in the frontal cortex of aged subjects that was even higher in aged Alzheimer's disease (AD) patients. However, the cause and the mechanism through which this increase occurs are still unknown. Here, we aimed to investigate whether the upregulation of GLUT12 in AD is related with aging or A beta deposition in comparison with GLUT1, GLUT3, and GLUT4. In the frontal cortex of two amyloidogenic mouse models (Tg2576 and APP/PS1) GLUT12 levels were increased. Contrary, expression of GLUT1 and GLUT3 were decreased, while GLUT4 did not change. In aged mice and the senescence-accelerated model SAMP8, GLUT12 and GLUT4 were upregulated in comparison with young animals. GLUT1 and GLUT3 did not show significant changes with age. The effect of beta-amyloid (A beta) deposition was also evaluated in A beta peptide i.c.v. injected mice. In the hippocampus, GLUT12 expression increased whereas GLUT4 was not modified. Consistent with the results in the amyloidogenic models, GLUT3 and GLUT1 were downregulated. In summary, A beta increases GLUT12 protein expression in the brain pointing out a central role of the transporter in AD pathology and opening new perspectives for the treatment of this neurodegenerative disease.
Autores: Pérez González, Marta; Mendioroz, M.; Badesso, Sara; et al.
ISSN 0301-0082  Vol. 191  2020  págs. 101818
Clinical studies revealed that some aged-individuals accumulate a significant number of histopathological Alzheimer's disease (AD) lesions in their brain, yet without developing any signs of dementia. Animal models of AD represent suitable tools to identify genes that might promote cognitive resilience and hence, this study first set out to identify cognitively resilient individuals in the aged-Tg2576 mouse model. A transcriptomic analysis of these mice identified PLA2G4E as a gene that might confer resistance to dementia. Indeed, a significant decrease in PLA2G4E is evident in the brain of late-stage AD patients, whereas no such changes are observed in early stage patients with AD neuropathological lesions but no signs of dementia. We demonstrated that adeno-associated viral vector-mediated overexpression of PLA2G4E in hippocampal neurons completely restored cognitive deficits in elderly APP/PS1 mice, without affecting the amyloid or tau pathology. These PLA2G4E overexpressing APP/ PS1 mice developed significantly more dendritic spines than sham-injected mice, coinciding with the cognitive improvement observed. Hence, these results support the idea that a loss of PLA2G4E might play a key role in the onset of dementia in AD, highlighting the potential of PLA2G4E overexpression as a novel therapeutic strategy to manage AD and other disorders that course with memory deficits.
Autores: Rabal Gracia, María Obdulia; Sanchez-Arias, J. A.; Cuadrado Tejedor, María del Mar; et al.
ISSN 1948-7193  Vol. 10  Nº 3  2019  págs. 1765 - 1782
In order to determine the contributions of histone deacetylase (HDAC) isoforms to the beneficial effects of dual phosphodiesterase 5 (PDES) and pan-HDAC inhibitors on in vivo models of Alzheimer's disease (AD), we have designed, synthesized, and tested novel chemical probes with the desired target compound profile of PDES and class I HDAC selective inhibitors. Compared to previous hydroxamate-based series, these molecules exhibit longer residence times on HDACs. In this scenario, shorter or longer preincubation times may have a significant impact on the IC50 values of these compounds and therefore on their corresponding selectivity profiles on the different HDAC isoforms. On the other hand, different chemical series have been explored and, as expected, some pairwise comparisons show a clear impact of the scaffold on biological responses (e.g., 35a vs 40a). The lead identification process led to compound 29a, which shows an adequate ADME-Tox profile and in vivo target engagement (histone acetylation and cAMP/cGMP response element-binding (CREB) phosphorylation) in the central nervous system (CNS), suggesting that this compound represents an optimized chemical probe; thus, 29a has been assayed in a mouse model of AD (Tg2576).
Autores: Cuadrado Tejedor, María del Mar; Pérez González, Marta; Garcia-Munoz, C. ; et al.
ISSN 1663-4365  Vol. 11  2019  págs. 149
The discouraging results with therapies for Alzheimer's disease (AD) in clinical trials, highlights the urgent need to adopt new approaches. Like other complex diseases, it is becoming clear that AD therapies should focus on the simultaneous modulation of several targets implicated in the disease. Recently, using reference compounds and the first-in class CM-414, we demonstrated that the simultaneous inhibition of histone deacetylases [class I histone deacetylases (HDACs) and HDAC6] and phosphodiesterase 5 (PDE5) has a synergistic therapeutic effect in AD models. To identify the best inhibitory balance of HDAC isoforms and PDEs that provides a safe and efficient therapy to combat AD, we tested the compound CM-695 in the Tg2576 mouse model of this disease. CM-695 selectively inhibits HDAC6 over class I HDAC isoforms, which largely overcomes the toxicity associated with HDAC class 1 inhibition. Furthermore, CM-695 inhibits PDE9, which is expressed strongly in the brain and has been proposed as a therapeutic target for AD. Chronic treatment of aged Tg2576 mice with CM-695 ameliorates memory impairment and diminishes brain A beta although its therapeutic effect was no longer apparent 4 weeks after the treatment was interrupted. An increase in the presence of 78-KDa glucose regulated protein (GRP78) and heat shock protein 70 (Hsp70) chaperones may underlie the therapeutic effect of CM-695. In summary, chronic treatment with CM-695 appears to reverse the AD phenotype in a safe and effective manner. Taking into account that AD is a multifactorial disorder, the multimodal action of these compounds and the different events they affect may open new avenues to combat AD.
Autores: Raygene, M, (Autor de correspondencia); Liefhebber, JM; García Osta, Ana María; et al.
ISSN 2162-2531  Vol. 16  2019  págs. 26 - 37
Autores: Rabal, O., (Autor de correspondencia); Sanchez-Arias, J. A.; Cuadrado Tejedor, María del Mar; et al.
ISSN 1948-7193  Vol. 10  Nº 9  2019  págs. 4076 - 4101
Here, we present a series of dual-target phosphodiesterase 9 (PDE9) and histone deacetylase (HDAC) inhibitors devised as pharmacological tool compounds for assessing the implications of these two targets in Alzheimer's disease (AD). These novel inhibitors were designed taking into account the key pharmacophoric features of known selective PDE9 inhibitors as well as privileged chemical structures, bearing zinc binding groups (hydroxamic acids and ortho-amino anilides) that hit HDAC targets. These substituents were selected according to rational criteria and previous knowledge from our group to explore diverse HDAC selectivity profiles (pan-HDAC, HDAC6 selective, and class I selective) that were confirmed in biochemical screens. Their functional response in inducing acetylation of histone and tubulin and phosphorylation of cAMP response element binding (CREB) was measured as a requisite for further progression into complete in vitro absorption, distribution, metabolism and excretion (ADME) and in vivo brain penetration profiling. Compound 31b, a selective HDAC6 inhibitor with acceptable brain permeability, was chosen for assessing in vivo efficacy of these first-in-class inhibitors, as well as studying their mode of action (MoA).
Autores: Aldave, G.; González Huarriz, María Soledad; Rubio Díaz-Cordoves, Ángel; et al.
ISSN 1522-8517  Vol. 20  Nº 7  2018  págs. 930 - 941
Background: Glioblastoma, the most aggressive primary brain tumor, is genetically heterogeneous. Alternative splicing (AS) plays a key role in numerous pathologies, including cancer. The objectives of our study were to determine whether aberrant AS could play a role in the malignant phenotype of glioma and to understand the mechanism underlying its aberrant regulation. Methods: We obtained surgical samples from patients with glioblastoma who underwent 5-aminolevulinic fluorescence-guided surgery. Biopsies were taken from the tumor center as well as from adjacent normal-appearing tissue. We used a global splicing array to identify candidate genes aberrantly spliced in these glioblastoma samples. Mechanistic and functional studies were performed to elucidate the role of our top candidate splice variant, BAF45d, in glioblastoma. Results: BAF45d is part of the switch/sucrose nonfermentable complex and plays a key role in the development of the CNS. The BAF45d/6A isoform is present in 85% of over 200 glioma samples that have been analyzed and contributes to the malignant glioma phenotype through the maintenance of an undifferentiated cellular state. We demonstrate that BAF45d splicing is mediated by polypyrimidine tract-binding protein 1 (PTBP1) and that BAF45d regulates PTBP1, uncovering a reciprocal interplay between RNA splicing regulation and transcription. Conclusions: Our data indicate that AS is a mechanism that contributes to the malignant phenotype of glioblastoma. Understanding the consequences of this biological process will uncover new therapeutic targets for this devastating disease.
Autores: Lasarte, Aritz; Lozano Moreda, Teresa; Pérez González, Marta; et al.
ISSN 1664-3224  Vol. 9  Nº JAN  2018  págs. Article number: 68
A complex network of interactions exists between the immune, the olfactory, and the central nervous system (CNS). Inhalation of different fragrances can affect immunological reactions in response to an antigen but also may have effects on the CNS and cognitive activity. We performed an exploratory study of the immunomodulatory ability of a series of compounds representing each of the 10 odor categories or clusters described previously. We evaluated the impact of each particular odor on the immune response after immunization with the model antigen ovalbumin in combination with the TLR3 agonist poly I:C. We found that some odors behave as immunostimulatory agents, whereas others might be considered as potential immunosuppressant odors. Interestingly, the immunomodulatory capacity was, in some cases, strain-specific. In particular, one of the fragrances, carvone, was found to be immunostimulatory in BALB/c mice and immunosuppressive in C57BL/6J mice, facilitating or impairing viral clearance, respectively, in a model of a viral infection with a recombinant adenovirus. Importantly, inhalation of the odor improved the memory capacity in BALB/c mice in a fear-conditioning test, while it impaired this same capacity in C57BL/6J mice. The improvement in memory capacity in BALB/c was associated with higher CD3+ T cell infiltration into the hippocampus and increased local expression of mRNA coding for IL-1ß, TNF-¿, and IL-6 cytokines. In contrast, the memory impairment in C57BL/6 was associated with a reduction in CD3 numbers and an increase in IFN-¿. These data suggest an association between the immunomodulatory capacity of smells and their impact on the cognitive functions of the animals. These results highlight the potential of studying odors as therapeutic agents for CNS-related diseases.
Autores: Ugarte, A.; Corbacho, D.; Aymerich Soler, Marisol; et al.
ISSN 1933-7213  Vol. 15  Nº 3  2018  págs. 742 - 750
Drug efficacy in the central nervous system (CNS) requires an additional step after crossing the blood-brain barrier. Therapeutic agents must reach their targets in the brain to modulate them; thus, the free drug concentration hypothesis is a key parameter for in vivo pharmacology. Here, we report the impact of neurodegeneration (Alzheimer's disease (AD) and Parkinson's disease (PD) compared with healthy controls) on the binding of 10 known drugs to postmortem brain tissues from animal models and humans. Unbound drug fractions, for some drugs, are significantly different between healthy and injured brain tissues (AD or PD). In addition, drugs binding to brain tissues from AD and PD animal models do not always recapitulate their binding to the corresponding human injured brain tissues. These results reveal potentially relevant implications for CNS drug discovery.
Autores: Rabal Gracia, María Obdulia; Sanchez-Arias, J. A.; Cuadrado Tejedor, María del Mar; et al.
ISSN 0223-5234  Vol. 150  2018  págs. 506 - 524
We have identified chemical probes that act as dual phosphodiesterase 5 (PDE5) and histone deacetylase 6 (HDAC6)-selective inhibitors (>1 log unit difference versus class I HDACs) to decipher the contribution of HDAC isoforms to the positive impact of dual-acting PDE5 and HDAC inhibitors on mouse models of Alzheimer's disease (AD) and fine-tune this systems therapeutics approach. Structure- and knowledge based approaches led to the design of first-in-class molecules with the desired target compound profile: dual PDE5 and HDAC6-selective inhibitors. Compound 44b, which fulfilled the biochemical, functional and ADME-Tox profiling requirements and exhibited adequate pharmacokinetic properties, was selected as pharmacological tool compound and tested in a mouse model of AD (Tg2576) in vivo. (C) 2018 Elsevier Masson SAS. All rights reserved.
Autores: Sanchez-Arias, J. A.; Rabal Gracia, María Obdulia; Cuadrado Tejedor, María del Mar; et al.
ISSN 1948-7193  Vol. 15  Nº 8  2017  págs. 638 - 661
Sánchez-Arias J.A.; María Obdulia Rabal Gracia; María del Mar Cuadrado Tejedor; Ana María García Osta and Julen Oyarzábal Santamarina, contributed equally to this work. ABSTRACT: A novel systems therapeutics approach, involving simultaneous inhibition of phosphodiesterase 5 (PDE5) and histone deacetylase (HDAC), has been validated as a potentially novel therapeutic strategy for the treatment of Alzheimer's disease (AD). First-in-class dual inhibitors bearing a sildenafil core have been very recently reported, and the lead molecule 7 has proven this strategy in AD animal models. Because scaffolds may play a critical role in primary activities and ADME-Tox profiling as well as on intellectual property, we have explored alternative scaffolds (vardenafil- and tadalafil-based cores) and evaluated their impact on critical parameters such as primary activities, permeability, toxicity, and in vivo (pharmacokinetics and functional response in hippocampus) to identify a potential alternative lead molecule bearing a different chemotype for in vivo testing.
Autores: Cuadrado Tejedor, María del Mar; Garcia Barroso, Carolina; Sanchez-Arias, J. A.; et al.
ISSN 0893-133X  Vol. 42  Nº 2  2017  págs. 524 - 539
The targeting of two independent but synergistic enzymatic activities, histone deacetylases (HDACs, class I and HDAC6) and phosphodiesterase 5 (PDE5), has recently been validated as a potentially novel therapeutic approach for Alzheimer's disease (AD). Here we report the discovery of a new first-in-class small-molecule (CM-414) that acts as a dual inhibitor of PDE5 and HDACs. We have used this compound as a chemical probe to validate this systems therapeutics strategy, where an increase in the activation of cAMP/cGMP-responsive element-binding protein (CREB) induced by PDE5 inhibition, combined with moderate HDAC class I inhibition, leads to efficient histone acetylation. This molecule rescued the impaired long-term potentiation evident in hippocampal slices from APP/PS1 mice. Chronic treatment of Tg2576 mice with CM-414 diminished brain Aß and tau phosphorylation (pTau) levels, increased the inactive form of GSK3ß, reverted the decrease in dendritic spine density on hippocampal neurons, and reversed their cognitive deficits, at least in part by inducing the expression of genes related to synaptic transmission. Thus, CM-414 may serve as the starting point to discover balanced dual inhibitors with an optimal efficacy and safety profile for clinical testing on AD patients.
Autores: Rabal Gracia, María Obdulia; Sánchez-Arias, J. A.; Cuadrado Tejedor, María del Mar; et al.
ISSN 0022-2623  Vol. 59  Nº 19  2016  págs. 8967-9004
Simultaneous inhibition of phosphodiesterase 5 (PDE5) and histone deacetylases (HDAC) has recently been validated as a potentially novel therapeutic approach for Alzheimer's disease (AD). To further extend this concept, we designed and synthesized the first chemical series of dual acting PDE5 and HDAC inhibitors, and we validated this systems therapeutics approach. Following the implementation of structure- and knowledge-based approaches, initial hits were designed and were shown to validate our hypothesis of dual in vitro inhibition. Then, an optimization strategy was pursued to obtain a proper tool compound for in vivo testing in AD models. Initial hits were translated into molecules with adequate cellular functional responses (histone acetylation and cAMP/cGMP response element-binding (CREB) phosphorylation in the nanomolar range), an acceptable therapeutic window (>1 log unit), and the ability to cross the blood-brain barrier, leading to the identification of 7 as a candidate for in vivo proof-of-concept testing ( Cuadrado-Tejedor, M.; Garcia-Barroso, C.; Sánchez-Arias, J. A.; Rabal, O.; Mederos, S.; Ugarte, A.; Franco, R.; Segura, V.; Perea, G.; Oyarzabal, J.; Garcia-Osta, A. Neuropsychopharmacology 2016 , in press, doi: 10.1038/npp.2016.163 ).
Autores: Gómez-Vallejo, V.; Ugarte, A.; Garcia Barroso, Carolina; et al.
ISSN 0022-3042  Vol. 136  Nº 2  2016  págs. 403 - 415
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.
Autores: Peixoto, C. A.; Nunes, A. K.; García Osta, Ana María
ISSN 0962-9351  Vol. 2015  2015  págs. 940207
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.
Autores: Ugarte, A.; Gil Bea, Francisco Javier; Garcia Barroso, Carolina; et al.
ISSN 0305-1846  Vol. 41  Nº 4  2015  págs. 471 - 482
AIMS: Levels of the cyclic nucleotides guanosine 3', 5'-monophosphate (cGMP) or adenosine 3', 5'-monophosphate (cAMP) that play important roles in memory processes are not characterized in Alzheimer's disease (AD). The aim of this study was to analyse the levels of these nucleotides in cerebrospinal fluid (CSF) samples from patients diagnosed with clinical and prodromal stages of AD and study the expression level of the enzymes that hydrolyzed them [phosphodiesterases (PDEs)] in the brain of AD patients vs. METHODS: For cGMP and cAMP CSF analysis, the cohort (n¿=¿79) included cognitively normal participants (subjective cognitive impairment), individuals with stable mild cognitive impairment or AD converters (sMCI and cMCI), and mild AD patients. A high throughput liquid chromatography-tandem mass spectrometry method was used. Interactions between CSF cGMP or cAMP with mini-mental state examination (MMSE) score, CSF Aß(1-42) and CSF p-tau were analysed. For PDE4, 5, 9 and 10 expression analysis, brains of AD patients vs. controls (n¿=¿7 and n¿=¿8) were used. RESULTS: cGMP, and not cAMP levels, were significantly lower in the CSF of patients diagnosed with mild AD when compared with nondemented controls. CSF levels of cGMP showed a significant association with MMSE-diagnosed clinical dementia and with CSF biomarker Aß42 in AD patients. Significant increase in PDE5 expression was detected in temporal cortex of AD patients compared with that of age-matched healthy control subjects. No changes in the expression of others PDEs were detected. CONCLUSIONS: These results support the potential involvement of cGMP in the pathological and clinical development of AD. The cGMP reduction in early stages of AD might participate in the aggravation of amyloid pathology and cognitive decline.
Autores: Cuadrado Tejedor, María del Mar; Garcia Barroso, Carolina; Sanchez-Arias, J. A.; et al.
ISSN 1868-7083  Vol. 7  2015  págs. 108
BACKGROUND: Given the implication of histone acetylation in memory processes, histone deacetylase inhibitors (HDACIs) have been postulated as potential modulators of cognitive impairment in Alzheimer's disease (AD). However, dose-dependent side effects have been described in patients with the currently available broad-spectrum HDACIs, explaining why their therapeutic potential has not been realized for chronic diseases. Here, by simultaneously targeting two independent enzyme activities, histone deacetylase (HDAC) and phosphodiesterase-5 (PDE5), we propose a novel mode of inhibitory action that might increase the therapeutic specificity of HDACIs. RESULTS: The combination of vorinostat, a pan-HDACI, and tadalafil, a PDE5 inhibitor, rescued the long-term potentiation impaired in slices from APP/PS1 mice. When administered in vivo, the combination of these drugs alleviated the cognitive deficits in AD mice, as well as the amyloid and tau pathology, and it reversed the reduced dendritic spine density on hippocampal neurons. Significantly, the combination of vorinostat and tadalafil was more effective than each drug alone, both against the symptoms and in terms of disease modification, and importantly, these effects persisted after a 4-week washout period. CONCLUSIONS: The results highlight the pharmacological potential of a combination of molecules that inhibit HDAC and PDE5 as a therapeutic approach for AD treatment.
Autores: Cuadrado Tejedor, María del Mar; García Osta, Ana María
ISSN 1664-2295  Vol. 5  2014  págs. 182
Autores: Pascual Lucas, María Rafaela; Viana-da-Silva, S.; Di Scala, Marianna; et al.
ISSN 1757-4676  Vol. 6  Nº 10  2014  págs. 1246 - 1262
Insulin-like growth factor 2 (IGF2) was recently found to play a critical role in memory consolidation in rats and mice, and hippocampal or systemic administration of recombinant IGF2 enhances memory. Here, using a gene therapy-based approach with adeno-associated virus (AAV), we show that IGF2 overexpression in the hippocampus of aged wild-type mice enhances memory and promotes dendritic spine formation. Furthermore, we report that IGF2 expression decreases in the hippocampus of patients with Alzheimer's disease, and this leads us to hypothesize that increased IGF2 levels may be beneficial for treating the disease. Thus, we used the AAV system to deliver IGF2 or IGF1 into the hippocampus of the APP mouse model Tg2576 and demonstrate that IGF2 and insulin-like growth factor 1 (IGF1) rescue behavioural deficits, promote dendritic spine formation and restore normal hippocampal excitatory synaptic transmission. The brains of Tg2576 mice that overexpress IGF2 but not IGF1 also show a significant reduction in amyloid levels. This reduction probably occurs through an interaction with the IGF2 receptor (IGF2R). Hence, IGF2 and, to a lesser extent, IGF1 may be effective treatments for Alzheimer's disease.
Autores: Gaja, V.; Gomez-Vallejo, V.; Puigivila, M.; et al.
ISSN 1536-1632  Vol. 16  Nº 4  2014  págs. 538 - 549
PURPOSE: The aim of the present study was to develop short half-lived tools for in vitro and in vivo ß-amyloid imaging in mice, for which no suitable PET tracers are available. PROCEDURES: Five (13)N-labelled azo compounds (1-5) were synthesized using a three-step process using cyclotron-produced [(13)N]NO3 (-). Biodistribution studies were performed using positron emission tomography-computed tomography (PET-CT) on 20-month-old healthy, wild-type (WT) mice. In vivo and in vitro binding assays were performed using PET-CT and autoradiography, respectively, on 20-month-old healthy (WT) mice and transgenic (Tg2576) Alzheimer's disease model mice. RESULTS: (13)N-labelled azo compounds were prepared with decay corrected radiochemical yields in the range 27¿±¿4 % to 39¿±¿4 %. Biodistribution studies showed good blood-brain barrier penetration for compounds 1 and 3-5; good clearance data were also obtained for compounds 1-3 and 5. Compounds 2, 3 and 5 (but not 1) showed a significant uptake in ß-amyloid-rich structures when assayed in in vitro autoradiographic studies. PET studies showed significant uptake of compounds 2 and 3 in the cortex of transgenic animals that exhibit ß-amyloid deposits.
Autores: Garcia Barroso, Carolina; Ugarte, A.; Martínez Villar, Martín; et al.
ISSN 1387-2877  Vol. 42   Nº Suppl. 4  2014  págs. S561 - S573
Understanding the cellular and molecular processes involved in learning and memory will help in the development of safe and effective cognitive enhancers. The cAMP response element-binding (CREB) may be a universal modulator of processes required for memory formation, and increasing the levels of second messengers like cAMP and cGMP could ultimately lead to CREB activation. Phosphodiesterase (PDE) inhibitors regulate signaling pathways by elevating cAMP and/or cGMP levels, and they have been demonstrated to improve learning and memory in a number of rodent models of impaired cognition. The aim of this review is to summarize the outstanding progress that has been made in the application of PDE inhibitors for memory dysfunction. In addition, we have introduced some recent data we generated demonstrating that tadalafil could be considered as an optimal candidate for drug re-positioning and as a good candidate to enhance cognition.
Autores: Cuadrado Tejedor, María del Mar; Oyarzabal Santamarina, Julen; Pascual Lucas, María Rafaela; et al.
ISSN 1868-5021  Vol. 4  Nº 5  2013  págs. 433 - 445
Epigenetic processes, such as DNA methylation and histone acetylation, regulate the genome-environment interactions that may play important roles in a wide range of brain disorders, including Alzheimer's disease (AD). Indeed, the role of epigenetic machinery in learning and memory processes is well documented. In this review, we will focus on the most recent literature on tools that target epigenetic mechanisms, particularly on histone acetylation, and we will discuss the use of chemical probes to validate these targets in therapeutic strategies for AD.
Autores: Cuadrado Tejedor, María del Mar; Ricobaraza Abarquero, Ana; Torrijo, R.; et al.
ISSN 1381-6128  Vol. 19  Nº 28  2013  págs. 5076 - 5084
4-Phenylbutyrate (PBA) is a histone deacetylase (HDAC) inhibitor whose efficacy in the Tg2576 mouse model of Alzheimer¿s disease (AD) is correlated with decreased tau phosphorylation, clearance of intraneuronal Aß and restoration of dendritic spine density in hippocampal CA1 pyramidal neurons. PBA is also a chemical chaperone that facilitates cell proteostasis. To determine the relative contributions of HDAC inhibition and chaperone-like activity in the anti-AD effects of PBA, we compared the effect of PBA with that of sodium butyrate (NaBu), an HDAC inhibitor with no chaperone activity. In neuronal cultures from Tg2576 mice, we observed a correlation between histone 3 acetylation and decreased p-tau levels. Moreover, we observed a decrease in the processing of the amyloid precursor protein (APP) in Tg2576 neurons treated with PBA, but not with NaBu. In Tg2576 mice administered PBA or NaBu for 3 weeks, only PBA normalized the pathological AD markers, implicating, at least in part, other mechanism as the chaperone-like activity in the reversal of the AD-like phenotype of Tg2576 mice. Furthermore, treatment with PBA but not NaBu prevented the neuronal loss in the hippocampus of hAPPWT-overexpressing mice, as was particularly evident in the CA1 layer. In addition to its activity as a HDAC inhibitor, the chaperone activity of PBA appears to at least partially, mediate its reversal of the AD phenotype in Tg2576 mice and its neuroprotective effect in a model of hippocampal neuronal
Autores: Garcia Barroso, Carolina; Ricobaraza, A. ; Pascual-Lucas, M.; et al.
ISSN 0028-3908  Vol. 64  2013  págs. 114 - 123
Previous studies have demonstrated that cognitive function can be restored in mouse models of Alzheimer's disease (AD) following administration of sildenafil, a specific PDE5 inhibitor (Puzzo et al., 2009; Cuadrado-Tejedor et al.). Another very potent PDE5 inhibitor with a longer half-life and safe in chronic treatments, tadalafil, may represent a better alternative candidate for AD therapy. However, tadalafil was proven unable to achieve similar benefits than those of sildenafil in AD animal models (Puzzo et al., 2009). The lack of efficacy was attributed to inability to cross the blood-brain barrier (BBB). In this paper we first measured the blood and brain levels of tadalafil to prove that the compound crosses BBB and that chronic treatment leads to accumulation in the brain of the J20 transgenic mouse model of AD. We demonstrated the presence of PDE5 mRNA in the brain of the mice and also in the human brain. After a 10 week treatment with either of these PDE5 inhibitors, the performance of the J20 mice in the Morris water maze test improved when compared with the transgenic mice that received vehicle. Biochemical analysis revealed that neither sildenafil nor tadalafil altered the amyloid burden, although both compounds reduced Tau phosphorylation in the mouse hippocampus. This study provides evidence of the potential benefits of a chronic tadalafil treatment in AD therapy. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
Autores: García Osta, Ana María; Cuadrado Tejedor, María del Mar; Garcia Barroso, Carolina; et al.
ISSN 1948-7193  Vol. 3   Nº 11  2012  págs. 832 - 844
Alzheimer's disease (AD) is the most common form of dementia among the elderly. In AD patients, memory loss is accompanied by the formation of beta-amyloid plaques and the appearance of tau in a pathological form. Given the lack of effective treatments for AD, the development of new management strategies for these patients is critical. The continued failure to find effective therapies using molecules aimed at addressing the anti-beta amyloid pathology has led researchers to focus on other non-amyloid-based approaches to restore memory function. Promising non-amyloid related candidate targets include phosphosdiesterases (PDEs), and indeed, Rolipram, a specific PDE4 inhibitor, was the first compound found to effectively restore cognitive deficits in animal models of AD. More recently, PDE5 inhibitors have also been shown to effectively restore memory function. Accordingly, inhibitors of other members of the PDE family may also improve memory performance in AD and non-AD animal models. Hence, in this review, we will summarize the data supporting the use of PDE inhibitors as cognitive enhancers and we will discuss the possible mechanisms of action underlying these effects. We shall also adopt a medicinal chemistry perspective that leads us to propose the most promising PDE candidates on the basis of inhibitor selectivity, brain distribution, and mechanism of action.
Autores: Cuadrado Tejedor, María del Mar; Ricobaraza Abarquero, Ana; Frechilla Manso, Diana Sara; et al.
ISSN 1387-2877  Vol. 28  Nº 3  2012  págs. 567-578
The etiology of the more common (sporadic) forms of Alzheimer's disease (AD) remains unknown, although age is the most important risk factor. Nevertheless, interactions between environmental risk factors and genetic background may also influence the onset and progression of sporadic AD. Chronic stress, associated with altered memory and other neurological processes, is thought to influence the pathogenesis of AD. Hence, we evaluated the effect of unpredictable and consecutive chronic mild stressors on the onset of an AD-related pathology in the Tg2576 mouse line that overexpresses the human amyloid-beta protein precursor with the Swedish mutation (hA beta PPSwe). Two months after exposure to chronic mild stress, 4 month-old animals that normally display no pathological features of AD, not only expressed pathological markers but also experienced cognitive dysfunction in the Morris water maze test. These findings suggest that chronic mild stress accelerates the onset of cognitive impairment and produces an increase in hippocampal amyloid-beta and phospho-tau levels on a background of AD susceptibility.
Autores: Cuadrado Tejedor, María del Mar; García Osta, Ana María; Ricobaraza Abarquero, Ana; et al.
ISSN 0929-8673  Vol. 18  Nº 36  2011  págs. 5545 - 5553
Autores: Cuadrado Tejedor, María del Mar; Ricobaraza Abarquero, Ana; del Río Zambrana, Joaquín; et al.
Revista: Behavioural Brain Research
ISSN 0166-4328  Vol. 220  Nº 2  2011  págs. 338 - 343
Autores: Ricobaraza Abarquero, Ana; Cuadrado Tejedor, María del Mar; García Osta, Ana María
ISSN 1093-9946  Vol. 3  2011  págs. 1375 - 1384
Autores: Chen, D. Y.; Stern, S. A.; García Osta, Ana María; et al.
Revista: NATURE
ISSN 0028-0836  Vol. 469  Nº 7331  2011  págs. 491 - 497
We report that, in the rat, administering insulin-like growth factor II (IGF-II, also known as IGF2) significantly enhances memory retention and prevents forgetting. Inhibitory avoidance learning leads to an increase in hippocampal expression of IGF-II, which requires the transcription factor CCAAT enhancer binding protein ß and is essential for memory consolidation. Furthermore, injections of recombinant IGF-II into the hippocampus after either training or memory retrieval significantly enhance memory retention and prevent forgetting. To be effective, IGF-II needs to be administered within a sensitive period of memory consolidation. IGF-II-dependent memory enhancement requires IGF-II receptors, new protein synthesis, the function of activity-regulated cytoskeletal-associated protein and glycogen-synthase kinase 3 (GSK3). Moreover, it correlates with a significant activation of synaptic GSK3ß and increased expression of GluR1 (also known as GRIA1) ¿-amino-3-hydroxy-5-methyl-4-isoxasolepropionic acid receptor subunits. In hippocampal slices, IGF-II promotes IGF-II receptor-dependent, persistent long-term potentiation after weak synaptic stimulation. Thus, IGF-II may represent a novel target for cognitive enhancement therapies.
Autores: Cuadrado Tejedor, María del Mar; Hervías Aldama, Isabel Icíar; Ricobaraza Abarquero, Ana; et al.
Revista: Br. J. Pharmacol
ISSN 0007-1188  Vol. 164  2011  págs. 2029 - 2041
Autores: Okvist, A.; Fagergren, P.; Whittard, J.; et al.
ISSN 0006-3223  Vol. 69  Nº 3  2011  págs. 245 - 252
BACKGROUND: Glutamatergic transmission in the amygdala is hypothesized as an important mediator of stimulus-reward associations contributing to drug-seeking behavior and relapse. Insight is, however, lacking regarding the amygdala glutamatergic system in human drug abusers. METHODS: We examined glutamate receptors and scaffolding proteins associated with the postsynaptic density in the human postmortem amygdala. Messenger RNA or protein levels were studied in a population of multidrug (seven heroin, eight cocaine, seven heroin/cocaine, and seven controls) or predominant heroin (29 heroin and 15 controls) subjects. RESULTS: The amygdala of drug abusers was characterized by a striking positive correlation (r > .8) between ¿-amino-3-hydroxy-5-methylisoxazole-4-propionic acid glutamate receptor subunit 1 (GluA1) and postsynaptic density protein-95 (PSD-95) mRNA levels, which was not evident in control subjects. Structural equation multigroup analysis of protein correlations also identified the relationship between GluA1 and PSD-95 protein levels as the distinguishing feature of abusers. In line with the GluA1-PSD-95 implications of enhanced synaptic plasticity, Homer 1b/c protein expression was increased in both heroin and cocaine users as was its binding partner, dynamin-3. Furthermore, there was a positive relationship between Homer 1b/c and dynamin-3 in drug abusers that reflected an increase in the direct physical coupling between the proteins. A noted age-related decline of Homer 1b/c-dynamin-3 interactions, as well as GluA1 levels, was blunted in abusers. CONCLUSIONS: Impairment of key components of the amygdala postsynaptic density and coupling to the endocytic zone, critical for the regulation of glutamate receptor cycling, may underlie heightened synaptic plasticity in human drug abusers.
Autores: Escribano Serrano, Luis; Simón Yarza, Ana María; Gimeno, E; et al.
Revista: Neuropsychopharmacology
ISSN 0893-133X  Vol. 35  Nº 7  2010  págs. 1593 - 1604
Autores: Puerta Ruiz de Azua, Elena; Hervías Aldama, Isabel Icíar; Barros Miñones, Lucía; et al.
ISSN 0969-9961  Vol. 38  Nº 2  2010  págs. 237 - 245
Autores: Taubenfeld, S. M.; Muravieva, E. V.; García Osta, Ana María; et al.
ISSN 0027-8424  Vol. 107  Nº 27  2010  págs. 12345 - 12350
Addicts repeatedly relapse to drug seeking even after years of abstinence, and this behavior is frequently induced by the recall of memories of the rewarding effects of the drug. Established memories, including those induced by drugs of abuse, can become transiently fragile if reactivated, and during this labile phase, known as reconsolidation, can be persistently disrupted. Here we show that, in rats, a morphine-induced place preference (mCPP) memory is linked to context-dependent withdrawal as disrupting the reconsolidation of the memory leads to a significant reduction of withdrawal evoked in the same context. Moreover, the hippocampus plays a critical role in linking the place preference memory with the context-conditioned withdrawal, as disrupting hippocampal protein synthesis and cAMP-dependent-protein kinase A after the reactivation of mCPP significantly weakens the withdrawal. Hence, targeting memories induced by drugs may represent an important strategy for attenuating context-conditioned withdrawal and therefore subsequent relapse in opiate addicts.
Autores: Ricobaraza Abarquero, Ana; Cuadrado Tejedor, María del Mar; Marco Martínez, Sonia; et al.
ISSN 1050-9631  Vol. 22  Nº 5  2010  págs. 1040 - 1050
Alzheimer's disease (AD) and ageing are associated with impaired learning and memory, and recent findings point toward modulating chromatin remodeling through histone acetylation as a promising therapeutic strategy. Here we report that systemic administration of the HDAC inhibitor 4-phenylbutyrate (PBA) reinstated fear learning in the Tg2576 mouse model of AD. Tg2576 mice develop age-dependent amyloid pathology and cognitive decline that closely mimics disease progression in humans. Memory reinstatement by PBA was observed independently of the disease stage: both in 6-month-old Tg2576 mice, at the onset of the first symptoms, but also in aged, 12- to 16-month-old mice, when amyloid plaque deposition and major synaptic loss has occurred. Reversal of learning deficits was associated to a PBA-induced clearance of intraneuronal Aß accumulation, which was accompanied by mitigation of endoplasmic reticulum (ER) stress, and to restoration of dendritic spine densities of hippocampal CA1 pyramidal neurons to control levels. Furthermore, the expression of plasticity-related proteins such as the NMDA receptor subunit NR2B and the synaptic scaffold SAP102 was significantly increased by PBA. Our data suggest that the beneficial effects of PBA in memory are mediated both via its chemical chaperone-like activity and via the transcriptional activation of a cluster of proteins required for the induction of synaptic plasticity and structural remodeling.
Autores: García Osta, Ana María; Cuadrado Tejedor, María del Mar
Libro:  Methods in Molecular Biology
Vol. 1303   2016  págs. 117-123
The 99-amino-acid-long APP-carboxy-terminal fragment, named C99, is a membrane-bound peptide generated from the amyloid precursor protein (APP) by ß-secretase cleavage and is the direct precursor of amyloid beta (Aß). Here we describe a method for the quantification of C99. The amount of C99 is an indicative value of the amyloid pathology in an Alzheimer's disease (AD) model, and could be used as a marker to study AD progression in comprehensive experiments, including screening for new compounds and repurposing of drugs to treat AD.
Autores: Cuadrado Tejedor, María del Mar; García Osta, Ana María
Libro:  Systems biology of Alzheimer's disease
Vol. 1303  2016  págs. 241 - 246
A comprehensive chronic mild stress (CMS) procedure is presented, which consists in the application of unpredictable mild stressors to animal models in a random order for several weeks. This assay can be applied to Alzheimer's disease (AD) mouse models, leading to accelerated onset and increased severity of AD phenotypes and signs, including memory deficits and the accumulation of amyloid-ß and phospho-tau. These assays open the way towards advanced studies on the influence of sustained mild stress, stress responses and pathways on the onset and propagation of Alzheimer's disease