Development of GMP-1 a molecular chaperone network modulator protecting mitochondrial function and its assessment in fly and mice models of Alzheimer's disease.

Mitochondrial dysfunction is an early feature of Alzheimer's disease (AD) and may play an important role in the pathogenesis of disease. It has been shown that amyloid beta peptide (Aß) and amyloid precursor protein (APP) interact with mitochondria contributing to the mitochondrial dysfunction in AD. Prevention of abnormal protein targeting to mitochondria can protect normal mitochondrial function, increase neuronal survival and at the end, ameliorate symptoms of AD and other neurodegenerative disorders. First steps of mitochondrial protein import are coordinated by molecular chaperones Hsp70 and Hsp90 that bind to the newly synthesized mitochondria-destined proteins and deliver them to the protein import receptors on the surface of organelle. Here, we have described the development of a novel compound named GMP-1 that disrupts interactions between Hsp70/Hsp90 molecular chaperones and protein import receptor Tom70. GMP-1 treatment of SH-SY5Y cells results in decrease in mitochondria-associated APP and protects SH-SY5Y cells from toxic effect of Aß1-42 exposure. Experiments in drosophila and mice models of AD demonstrated neuroprotective effect of GMP-1 treatment, improvement in memory and behaviour tests as well as restoration of mitochondrial function.

Brain cortical cholesterol metabolism is highly affected by human APP overexpression in mice.

Processing of the amyloid precursor protein (APP) and amyloid beta (Aß) has been for decades in the center of Alzheimer's disease (AD) research. Beside many other variables, lipids, especially cholesterol and its derivatives, are discussed to contribute to AD pathogenesis. Several studies show that cholesterol affects APP metabolism. Also the converse mechanism, the direct influence of Aß on cholesterol metabolism, has been described. To further investigate this crosstalk between cholesterol- and APP metabolism, a high-fat feeding study was conducted with animals overexpressing human APPSL and/or human ApoB-100. The impact of diet and genotype on cerebral cholesterol metabolism and content as well as spatial learning and memory was examined. While behavioral performance was not influenced by this high fat diet (HFD), reduction of cortical free cholesterol levels and mRNA expression patterns under normal diet and HFD conditions in human APPSL overexpressing mice argue for an important role of APP in cerebral lipid metabolism. From our results we conclude that increased APP metabolism in ApoBxAPP and APPSL mice induces mechanisms to reduce free cholesterol levels.

Late-stage α-synuclein accumulation in TNWT-61 mouse model of Parkinson's disease detected by diffusion kurtosis imaging.

Diffusion kurtosis imaging (DKI) by measuring non-Gaussian diffusion allows an accurate estimation of the distribution of water molecule displacement and may correctly characterize microstructural brain changes caused by neurodegeneration. The aim of this study was to evaluate the ability of DKI to detect changes induced by α-synuclein (α-syn) accumulation in α-syn over-expressing transgenic mice (TNWT-61) in both gray matter (GM) and white matter (WM) using region of interest (ROI) and tract-based spatial statistics analyses, respectively, and to explore the relationship between α-syn accumulation and DKI metrics in our regions of interest. Fourteen-month-old TNWT-61 mice and wild-type (WT) littermates underwent in vivo DKI scanning using the Bruker Avance 9.4 Tesla magnetic resonance imaging system. ROI analysis in the GM regions substantia nigra, striatum, hippocampus, sensorimotor cortex, and thalamus and tract-based spatial statistics analysis in WM were performed. Immunohistochemistry for α-syn was performed in TNWT-61 mice and correlated with DKI findings. We found increased kurtosis and decreased diffusivity values in GM regions such as the thalamus and sensorimotor cortex, and in WM regions such as the external and internal capsule, mamillothalamic tract, anterior commissure, cingulum, and corpus callosum in TNWT-61 mice as compared to WT mice. Furthermore, we report for the first time that α-syn accumulation is positively correlated with kurtosis and negatively correlated with diffusivity in the thalamus. The study provides evidence of an association between the amount of α-syn and the magnitude of DKI metric changes in the ROIs, with the potential of improving the clinical diagnosis of Parkinson's disease. We propose diffusion kurtosis imaging as a sensitive method for detecting human α-synuclein accumulation-induced changes in brain tissue, which may be reflective of Parkinson disease stage. Boxplots show the averaged mean kurtosis (orange) and mean diffusivity (blue) under the results of the analysis (*p < 0.05) in brains of wild-type (WT) and α-synuclein over-expressing (TNWT-61) mice. This approach might represent a novel biomarker for the early diagnosis of Parkinson's disease. Read the Editorial Highlight for this article on page 1117.

Influence of Lentiviral ß-Synuclein Overexpression in the Hippocampus of a Transgenic Mouse Model of Alzheimer's Disease on Amyloid Precursor Protein Metabolism and Pathology.

BACKGROUND: ß-Synuclein (ß-Syn) is a member of the highly homologous synuclein protein family. The most prominent family member, α-synuclein (α-Syn), abnormally accumulates in so-called Lewy bodies, one of the major pathological hallmarks of α-synucleinopathies. Notably, parts of the peptide backbone, called the nonamyloid component, are also found in amyloid plaques. However, ß-Syn seems to have beneficial effects by reducing α-Syn aggregation, and amyloid antiaggregatory activity has been described. OBJECTIVE: The aim of the study was to analyze if wild-type ß-Syn can counteract functional and pathological changes in a murine Alzheimer model over different time periods. METHODS: At the onset of pathology, lentiviral particles expressing human ß-Syn were injected into the hippocampus of transgenic mice overexpressing human amyloid precursor protein with Swedish and London mutations (APPSL). An empty vector served as the control. Behavioral analyses were performed 1, 3 and 6 months after injection followed by biochemical and histological examinations of brain samples. RESULTS: ß-Syn expression was locally concentrated and rather modest, but nevertheless changed its effect on APP expression and plaque load in a time- and concentration-dependent manner. Interestingly, the phosphorylation of glycogen synthase kinase 3 beta was enhanced in APPSL mice expressing human ß-Syn, but an inverse trend was observed in wild-type animals. CONCLUSION: The initially reported beneficial effects of ß-Syn could be partially reproduced, but locally elevated levels of ß-Syn might also cause neurodegeneration. To enlighten the controversial pathological mechanism of ß-Syn, further examinations considering the relationship between concentration and exposure time of ß-Syn are needed.

Neuroinflammation and related neuropathologies in APPSL mice: further value of this in vivo model of Alzheimer's disease.

BACKGROUND: Beyond cognitive decline, Alzheimer's disease (AD) is characterized by numerous neuropathological changes in the brain. Although animal models generally do not fully reflect the broad spectrum of disease-specific alterations, the APPSL mouse model is well known to display early plaque formation and to exhibit spatial learning and memory deficits. However, important neuropathological features, such as neuroinflammation and lipid peroxidation, and their progression over age, have not yet been described in this AD mouse model. METHODS: Hippocampal and neocortical tissues of APPSL mice at different ages were evaluated. One hemisphere from each mouse was examined for micro- and astrogliosis as well as concomitant plaque load. The other hemisphere was evaluated for lipid peroxidation (quantified by a thiobarbituric acid reactive substances (TBARS) assay), changes in Aß abundance (Aß38, Aß40 and Aß42 analyses), as well as determination of aggregated Aß content (Amorfix A4 assay). Finally, correlation analyses were performed to illustrate the time-dependent correlation between neuroinflammation and Aß load (soluble, insoluble, fibrils), or lipid peroxidation, respectively. RESULTS: As is consistent with previous findings, neuroinflammation starts early and shows strong progression over age in the APPSL mouse model. An analyses of concomitant Aß load and plaque deposition revealed a similar progression, and high correlations between neuroinflammation markers and soluble or insoluble Aß or fibrillar amyloid plaque loads were observed. Lipid peroxidation, as measured by TBARS levels, correlates well with neuroinflammation in the neocortex but not the hippocampus. The hippocampal lipid peroxidation correlated strongly with the increase of LOC positive fiber load, whereas neocortical TBARS levels were unrelated to amyloidosis. CONCLUSIONS: These data illustrate for the first time the progression of major AD related neuropathological features other than plaque load in the APPSL mouse model. Specifically, we demonstrate that microgliosis and astrocytosis are prominent aspects of this AD mouse model. The strong correlation of neuroinflammation with amyloid burden and lipid peroxidation underlines the importance of these pathological factors for the development of AD. The new finding of a different relation of lipid peroxidation in the hippocampus and neocortical regions show that the model might contribute to the understanding of complex pathological mechanisms and their interplay in AD.

We can treat Alzheimer's disease successfully in mice but not in men: failure in translation? A perspective.

BACKGROUND: Animal models closely resembling the etiopathogenesis of Alzheimer's disease (AD) are needed for research on disease mechanisms and for drug development. No natural model of AD is available, so big hopes arose from transgenic and knockout technology, expecting that modulation and expression of pathogenetically important proteins resemble human brain pathology and functional deficits in the expected morphological and temporal pattern. OBJECTIVE: The real usefulness of these models should be discussed from an objective point of view. RESULTS: Not a single one of the published transgenic rodent models fulfils this hope, and even complex multiple transgenic animals do not suffer from real AD. It is crucial to be aware that all of the commonly used mice and rats are just models, and therefore results from drug efficacy testing have to be interpreted with care. Repeated experience with failed trials of new treatments that previously had been published as successful in animals has led to the wrong conclusion that animal models are of low predictive value or even of no use. Often clinical trials replicate exactly what was shown in the animal proof-of-concept studies. CONCLUSION: The value of animal models depends mainly on the careful experimentation and correct interpretation of results. Appropriate planning of experiments will help to increase the predictive value in drug development programs, though this may also increase negative findings. However, the early failure may enable a faster focus on more promising strategies.

p75 neurotrophin receptor modulation in mild to moderate Alzheimer disease: a randomized, placebo-controlled phase 2a trial.

p75 neurotrophin receptor (p75NTR) signaling pathways substantially overlap with degenerative networks active in Alzheimer disease (AD). Modulation of p75NTR with the first-in-class small molecule LM11A-31 mitigates amyloid-induced and pathological tau-induced synaptic loss in preclinical models. Here we conducted a 26-week randomized, placebo-controlled, double-blinded phase 2a safety and exploratory endpoint trial of LM11A-31 in 242 participants with mild to moderate AD with three arms: placebo, 200 mg LM11A-31 and 400 mg LM11A-31, administered twice daily by oral capsules. This trial met its primary endpoint of safety and tolerability. Within the prespecified secondary and exploratory outcome domains (structural magnetic resonance imaging, fluorodeoxyglucose positron-emission tomography and cerebrospinal fluid biomarkers), significant drug-placebo differences were found, consistent with the hypothesis that LM11A-31 slows progression of pathophysiological features of AD; no significant effect of active treatment was observed on cognitive tests. Together, these results suggest that targeting p75NTR with LM11A-31 warrants further investigation in larger-scale clinical trials of longer duration. EU Clinical Trials registration: 2015-005263-16 ; ClinicalTrials.gov registration: NCT03069014 .

Time course and progression of wild type α-synuclein accumulation in a transgenic mouse model.

BACKGROUND: Progressive accumulation of α-synuclein (α-Syn) protein in different brain regions is a hallmark of synucleinopathic diseases, such as Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. α-Syn transgenic mouse models have been developed to investigate the effects of α-Syn accumulation on behavioral deficits and neuropathology. However, the onset and progression of pathology in α-Syn transgenic mice have not been fully characterized. For this purpose we investigated the time course of behavioral deficits and neuropathology in PDGF-ß human wild type α-Syn transgenic mice (D-Line) between 3 and 12 months of age. RESULTS: These mice showed progressive impairment of motor coordination of the limbs that resulted in significant differences compared to non-transgenic littermates at 9 and 12 months of age. Biochemical and immunohistological analyses revealed constantly increasing levels of human α-Syn in different brain areas. Human α-Syn was expressed particularly in somata and neurites of a subset of neocortical and limbic system neurons. Most of these neurons showed immunoreactivity for phosphorylated human α-Syn confined to nuclei and perinuclear cytoplasm. Analyses of the phenotype of α-Syn expressing cells revealed strong expression in dopaminergic olfactory bulb neurons, subsets of GABAergic interneurons and glutamatergic principal cells throughout the telencephalon. We also found human α-Syn expression in immature neurons of both the ventricular zone and the rostral migratory stream, but not in the dentate gyrus. CONCLUSION: The present study demonstrates that the PDGF-ß α-Syn transgenic mouse model presents with early and progressive accumulation of human α-Syn that is accompanied by motor deficits. This information is essential for the design of therapeutical studies of synucleinopathies.

Inhibition of acyl-coenzyme A: cholesterol acyl transferase modulates amyloid precursor protein trafficking in the early secretory pathway.

Amyloid beta-peptide (Abeta) has a central role in the pathogenesis of Alzheimer's disease (AD). Cellular cholesterol homeostasis regulates endoproteolytic generation of Abeta from the amyloid precursor protein (APP). Previous studies have identified acyl-coenzyme A: cholesterol acyltransferase (ACAT), an enzyme that regulates subcellular cholesterol distribution, as a potential therapeutic target for AD. Inhibition of ACAT activity decreases Abeta generation in cell- and animal-based models of AD through an unknown mechanism. Here we show that ACAT inhibition retains a fraction of APP molecules in the early secretory pathway, limiting the availability of APP for secretase-mediated proteolytic processing. ACAT inhibitors delayed the trafficking of immature APP molecules from the endoplasmic reticulum (ER) as shown by metabolic labeling and live-cell imaging. This resulted in partial ER retention of APP and enhanced ER-associated degradation of APP by the proteasome, without activation of the unfolded protein response pathway. The ratio of mature APP to immature APP was reduced in brains of mice treated with ACAT inhibitors, and strongly correlated with reduced brain APP-C99 and cerebrospinal fluid Abeta levels in individual animals. Our results identify a novel ACAT-dependent mechanism that regulates secretory trafficking of APP, likely contributing to decreased Abeta generation in vivo.

Safety and pharmacokinetics of the orally available antiprionic compound PRI-002: A single and multiple ascending dose phase I study.

INTRODUCTION: PRI-002 is an orally available anti-amyloid beta (Aß) prionic compound developed for direct disassembly of toxic Aß oligomers relevant to Alzheimer's disease. METHODS: Two placebo-controlled clinical phase I trials with oral dosing of PRI-002 were conducted in healthy young subjects: A single ascending dose trial (4, 12, 36, 108, or 320 mg PRI-002 or placebo) in 40 participants followed by a multiple ascending dose study with daily 160 mg PRI-002 for 14 days or 320 mg for 28 days in 24 participants. The main objectives were safety, tolerability, and evaluation of pharmacokinetic (PK) parameters. RESULTS: PRI-002 was safe and well tolerated after single and multiple oral administration up to the highest doses. PRI-002 was absorbed rapidly and drug exposure increased proportional to dose. During repeated daily administration, the drug accumulated by a factor of about three. Steady-state conditions were reached after 1 to 2 weeks. CONCLUSIONS: The safety and PK results encourage further clinical development of PRI-002.

Translational animal models for Alzheimer's disease: An Alzheimer's Association Business Consortium Think Tank.

Over 5 million Americans and 50 million individuals worldwide are living with Alzheimer's disease (AD). The progressive dementia associated with AD currently has no cure. Although clinical trials in patients are ultimately required to find safe and effective drugs, animal models of AD permit the integration of brain pathologies with learning and memory deficits that are the first step in developing these new drugs. The purpose of the Alzheimer's Association Business Consortium Think Tank meeting was to address the unmet need to improve the discovery and successful development of Alzheimer's therapies. We hypothesize that positive responses to new therapies observed in validated models of AD will provide predictive evidence for positive responses to these same therapies in AD patients. To achieve this goal, we convened a meeting of experts to explore the current state of AD animal models, identify knowledge gaps, and recommend actions for development of next-generation models with better predictability. Among our findings, we all recognize that models reflecting only single aspects of AD pathogenesis do not mimic AD. Models or combinations of new models are needed that incorporate genetics with environmental interactions, timing of disease development, heterogeneous mechanisms and pathways, comorbidities, and other pathologies that lead to AD and related dementias. Selection of the best models requires us to address the following: (1) which animal species, strains, and genetic backgrounds are most appropriate; (2) which models permit efficient use throughout the drug development pipeline; (3) the translatability of behavioral-cognitive assays from animals to patients; and (4) how to match potential AD therapeutics with particular models. Best practice guidelines to improve reproducibility also need to be developed for consistent use of these models in different research settings. To enhance translational predictability, we discuss a multi-model evaluation strategy to de-risk the successful transition of pre-clinical drug assets to the clinic.

The ACAT inhibitor CP-113,818 markedly reduces amyloid pathology in a mouse model of Alzheimer's disease.

Amyloid beta-peptide (Abeta) accumulation in specific brain regions is a pathological hallmark of Alzheimer's disease (AD). We have previously reported that a well-characterized acyl-coenzyme A: cholesterol acyltransferase (ACAT) inhibitor, CP-113,818, inhibits Abeta production in cell-based experiments. Here, we assessed the efficacy of CP-113,818 in reducing AD-like pathology in the brains of transgenic mice expressing human APP(751) containing the London (V717I) and Swedish (K670M/N671L) mutations. Two months of treatment with CP-113,818 reduced the accumulation of amyloid plaques by 88%-99% and membrane/insoluble Abeta levels by 83%-96%, while also decreasing brain cholesteryl-esters by 86%. Additionally, soluble Abeta(42) was reduced by 34% in brain homogenates. Spatial learning was slightly improved and correlated with decreased Abeta levels. In nontransgenic littermates, CP-113,818 also reduced ectodomain shedding of endogenous APP in the brain. Our results suggest that ACAT inhibition may be effective in the prevention and treatment of AD by inhibiting generation of the Abeta peptide.

Chromogranin B and Secretogranin II in transgenic mice overexpressing human APP751 with the London (V717I) and Swedish (K670M/N671L) mutations and in Alzheimer patients.

Chromogranin B and secretogranin II are major soluble constituents of large dense core vesicles of presynaptic structures and have been found in neuritic plaques of Alzheimer patients. We examined the distribution and expression of these peptides in both transgenic mice over expressing human amyloid-beta protein precursor APP751 with the London (V717I) and Swedish (K670M/N671L) mutations and in human post-mortem brain. In transgenic mice, the number of amyloid-beta plaques and chromogranin immunopositive plaques increased from 6 to 12 months. About 60% of amyloid-beta plaques were associated with chromogranin B and about 40% with secretogranin II. Chromogranin immunoreactivity appeared mainly as swollen dystrophic neurites. Neither synaptophysin- nor glial fibrillary acidic protein- immunoreactivity was expressed in chromogranin immunoreactive structures at any timepoint. Density of chromogranin peptides in hippocampal structures did not change in transgenic animals at any timepoint, even though animals had a poorer performance in the Morris water maze task. In conclusion, our findings in transgenic animals partly resembled findings in Alzheimer patients. Chromogranin peptides were associated with amyloid-beta plaques, but were not reduced in specific brain areas as previously reported by our group. Therefore specific changes of chromogranin peptides observed in Alzheimer patients can be related to amyloid-beta pathology only.

BACE1-cleavage of Sez6 and Sez6L is elevated in Niemann-Pick type C disease mouse brains.

It is intriguing that a rare, inherited lysosomal storage disorder Niemann-Pick type C (NPC) shares similarities with Alzheimer's disease (AD). We have previously reported an enhanced processing of ß-amyloid precursor protein (APP) by ß-secretase (BACE1), a key enzyme in the pathogenesis of AD, in NPC1-null cells. In this work, we characterized regional and temporal expression and processing of the recently identified BACE1 substrates seizure protein 6 (Sez6) and seizure 6-like protein (Sez6L), and APP, in NPC1-/- (NPC1) and NPC1+/+ (wt) mouse brains. We analysed 4-weeks old brains to detect the earliest changes associated with NPC, and 10-weeks of age to identify changes at terminal disease stage. Sez6 and Sez6L were selected due to their predominant cleavage by BACE1, and their potential role in synaptic function that may contribute to presentation of seizures and/or motor impairments in NPC patients. While an enhanced BACE1-cleavage of all three substrates was detected in NPC1 vs. wt-mouse brains at 4-weeks of age, at 10-weeks increased proteolysis by BACE1 was observed for Sez6L in the cortex, hippocampus and cerebellum of NPC1-mice. Interestingly, both APP and Sez6L were found to be expressed in Purkinje neurons and their immunostaining was lost upon Purkinje cell neurodegeneration in 10-weeks old NPC1 mice. Furthermore, in NPC1- vs. wt-mouse primary cortical neurons, both Sez6 and Sez6L showed increased punctuate staining within the endolysosomal pathway as well as increased Sez6L and BACE1-positive puncta. This indicates that a trafficking defect within the endolysosomal pathway may play a key role in enhanced BACE1-proteolysis in NPC disease. Overall, our findings suggest that enhanced proteolysis by BACE1 could be a part of NPC disease pathogenesis. Understanding the basic biology of BACE1 and the functional impact of cleavage of its substrates is important to better evaluate the therapeutic potential of BACE1 against AD and, possibly, NPC disease.

Is alpha-synuclein pathology a target for treatment of neurodegenerative disorders?

Since the discovery that mutations of alpha-synuclein (AS) gene are responsible for rare forms of familiar Parkinson's disease this synaptic protein attracted increased interest. AS is the main constituent of Lewy bodies. In spite the physiological function is still unclear there is an ongoing discussion if over-expression is already dangerous, or if toxicity is subjected to oligomers, protofibrilles or mature aggregates. The fact that the central hydrophobic part of AS is a constituent of amyloid plaques in Alzheimer patients and the finding that a majority of AD patients have Lewy bodies and Lewy neurites in specific brain areas, raised our interest in the possible contribution of AS to pathogenesis of AD. Beta-synuclein (betaS) a protein of the same gene family seems to be a naturally occurring anti aggregatory factor preventing AS aggregation in vitro and in vivo. The N-terminal amino acid sequence 1 to 15 is responsible for this effect. Based on this finding we synthesized a peptide library with different sequence variations. Several of these peptides displayed distinct neuroprotective activity in tissue culture models of neurodegeneration induced by oxidative stress or Abeta1-42. In spite these peptides have a short half-life, in vivo significant reduction in brain plaque load and improvement of behavioral deficits was demonstrated in an APP-tg mouse model after intranasal treatment for 2 months. KEGV, the shortest sequence was also active after intraperitoneal application. Neuroprotective data in tissue cultures and results from transgenic mice are some how in conflict because in vitro effects can not be explained by the antiaggregatory potential, but most likely by interaction of betaS derivates with anti-apoptotic PI3/Akt cell signaling or interference with anti-oxidative pathways (JNK/JIB). The possibility that such betaS derived peptidomimetics might act as neuroprotectants and at the same time prevent protein missfolding suggests possible therapeutic usefulness in different neurodegenerative disorders.

Localization and expression of substance P in transgenic mice overexpressing human APP751 with the London (V717I) and Swedish (K670M/N671L) mutations.

Substance P-like immunoreactivity (-LI) is found in neuritic plaques, and is reduced in patients suffering from Alzheimer disease (AD). In this study, we examined the distribution and expression of substance P in transgenic mice overexpressing human amyloid precursor protein (hAPP) APP751 with the London (V717I) and Swedish (K670M/N671L) mutations. Immunohistochemistry was performed to localize substance P- and glial fibrillary acidic protein-LI by confocal microscopy. In hAPP transgenic mice, the number of beta-amyloid plaques significantly increased from 6 to 12 months. About 5% of beta-amyloid plaques were substance P-immunoreactive. In transgenic mice, the morphology of substance P-immunoreactive structures changed by consisting of swollen and dystrophic neurites mostly associated with beta-amyloid plaques. The overall localization and the relative substance P densities were not different between wild type and transgenic mice at 6 and 12 months. At month 12, a dramatic change in the distribution pattern of substance P-LI was observed as it was now expressed in a high number of reactive astrocytes. This expression of substance P in astrocytes was mainly found in the hippocampal formation and thalamic nuclei with a preferential association with beta-amyloid plaques, whereas in cortical regions only faintly substance P-immunoreactive astrocytes were observed. This study indicates that substance P undergoes complex changes in this animal Alzheimer disease model. Future experiments including substance P antagonists are necessary to further explore the interaction between beta-amyloid deposits and substance P.

Apolipoprotein A-I coating of protamine-oligonucleotide nanoparticles increases particle uptake and transcytosis in an in vitro model of the blood-brain barrier.

Drug delivery to the brain is severely restricted by formation of tight junctions between adjacent brain capillary endothelial cells (BCEC). In the present study we have evaluated the effects of protamine-oligonucleotide nanoparticles (proticles) on the functional properties of primary porcine BCEC and characterized uptake and transcytosis of proticles by these cells. Proticles had no adverse effects on BCEC properties relevant to blood-brain barrier (BBB) function. Transcytosis of (125)I-labeled proticles across polarized BCEC cultures occurred in a time- and concentration-dependent manner. As apolipoproteins were suggested to enhance cellular proticle uptake, proticle coating was performed with apoA-I, the major apolipoprotein component of high density lipoproteins. Adsorption of apoA-I on the surface of proticles resulted in significantly improved uptake and transcytosis properties as compared to uncoated proticles. ApoA-I coating enhanced proticle delivery to astrocytes in an in vitro model of the BBB almost twofold. Blocking of scavenger receptor class B, type I (the prime receptor for high density lipoprotein/apoA-I that is expressed on BCEC) reduced transcytosis of apoA-I-coated proticles to levels observed for uncoated proticles. Our data indicate that apoA-I-coating of proticles could be a feasible targeting technology to improve delivery across the BBB.

Scopolamine disrupts place navigation in rats and humans: a translational validation of the Hidden Goal Task in the Morris water maze and a real maze for humans.

RATIONALE: Development of new drugs for treatment of Alzheimer's disease (AD) requires valid paradigms for testing their efficacy and sensitive tests validated in translational research. OBJECTIVES: We present validation of a place-navigation task, a Hidden Goal Task (HGT) based on the Morris water maze (MWM), in comparable animal and human protocols. METHODS: We used scopolamine to model cognitive dysfunction similar to that seen in AD and donepezil, a symptomatic medication for AD, to assess its potential reversible effect on this scopolamine-induced cognitive dysfunction. We tested the effects of scopolamine and the combination of scopolamine and donepezil on place navigation and compared their effects in human and rat versions of the HGT. Place navigation testing consisted of 4 sessions of HGT performed at baseline, 2, 4, and 8 h after dosing in humans or 1, 2.5, and 5 h in rats. RESULTS: Scopolamine worsened performance in both animals and humans. In the animal experiment, co-administration of donepezil alleviated the negative effect of scopolamine. In the human experiment, subjects co-administered with scopolamine and donepezil performed similarly to subjects on placebo and scopolamine, indicating a partial ameliorative effect of donepezil. CONCLUSIONS: In the task based on the MWM, scopolamine impaired place navigation, while co-administration of donepezil alleviated this effect in comparable animal and human protocols. Using scopolamine and donepezil to challenge place navigation testing can be studied concurrently in animals and humans and may be a valid and reliable model for translational research, as well as for preclinical and clinical phases of drug trials.

Adamantane - A Lead Structure for Drugs in Clinical Practice.

The adamantane moiety is the structural backbone of numerous compounds and its discovery launched a new field of chemistry studying the approaches to the synthesis as well as the physicochemical and biological properties of organic polyhedral compounds with practical application in the pharmaceutical industry. Adamantane derivatives have proven to be very potent compounds in a wide range of applications from systemic to topical therapy. This review summarizes the currently available adamantane derivatives in clinical practice (amantadine, memantine, rimantadine, tromantadine, adapalene, saxagliptin, vildagliptin), focusing on mechanisms of action, pharmacokinetics, pharmacodynamics and clinical trials. The adamantane-based compounds presented in this manuscript have been approved for a wide spectrum of indications (antivirals, antidiabetics and against Alzheimer's and Parkinson's disease). Each of the compounds proved to be of vital importance in their therapeutic indication for numerous patients worldwide. This review also considers the mechanisms of side effects to deliver a complete perspective on current treatment options.