Pharmacotherapeutic approaches to the treatment of Alzheimer's disease

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Therapeutic Molecular Insights into the Active Engagement of Cannabinoids in the Therapy of Parkinson's Disease: A Novel and Futuristic Approach

Parkinson's disease is a neurodegenerative disorder which is characterised mostly by loss of dopaminergic nerve cells throughout the nigral area mainly as a consequence of oxidative stress. Muscle stiffness, disorganised bodily responses, disturbed sleep, weariness, amnesia, and voice impairment are all symptoms of dopaminergic neuron degeneration and existing symptomatic treatments are important to arrest additional neuronal death. Some cannabinoids have recently been demonstrated as robust antioxidants that might protect the nerve cells from degeneration even when cannabinoid receptors are not triggered. Cannabinoids are likely to have property to slow or presumably cease the steady deterioration of the brain's dopaminergic systems, a condition for which there is now no treatment. The use of cannabinoids in combination with currently available drugs has the potential to introduce a radically new paradigm for treatment of Parkinson's disease, making it immensely useful in the treatment of such a debilitating illness.

Structure-based discovery and development of novel O-GlcNAcase inhibitors for the treatment of Alzheimer's disease

The neurofibrillary tangles (NFTs) formed from hyperphosphorylation of tau protein are closely associated with Alzheimer's disease (AD). O-GlcNAcylation of tau can negatively regulate hyperphosphorylation and the O-GlcNAcase (OGA) catalyzes the removal of O-linked β-N-acetylglucosamine (O-GlcNAc) from tau protein. Therefore, preventing tau hyperphosphorylation by increasing the levels of tau O-GlcNAcylation via OGA inhibitors could be a promising approach. Based on Thiamet-G, a potent OGA inhibitor, and its binding mode to OGA, a novel OGA inhibitor scaffold bearing three parts was designed and hit compound 7j was successfully identified via extensive exploring. Further chemical optimization and diversification of the 7j structure resulted in compound 39 which possesses excellent OGA inhibition, no cytotoxicity, and has good pharmacokinetic properties. In acute AD model mice, 39 was more effective than Thiamet-G in inhibiting OGA activity attributable to its better blood-brain barrier permeability. In addition, 39 restored the cognitive function in mice and reduced amyloid-β (Aβ) concentrations to a greater extent than Thiamet-G. Molecular docking studies demonstrated that 39 was well associated with OGA through H-bonds and hydrophobic interaction. Together, these findings suggest that 39 was promising as a potent OGA inhibitor in the treatment of AD.

Discovery of novel berberine derivatives with balanced cholinesterase and prolyl oligopeptidase inhibition profile

Berberine, a naturally occurring compound, possesses an interesting multipotent pharmacological profile potentially applicable for Alzheimer's disease (AD) treatment. In this study, a series of novel 22 berberine derivatives was developed and tested in vitro. Berberine core was substituted at position 9-O of its aromatic ring region. All the hybrids under the study revealed multi-targeted profile inhibiting prolyl oligopeptidase, acetylcholinesterase and butyrylcholinesterase highlighting 4a, 4g, 4j, 4l and 4s possessing balanced activities in the micromolar range. The top-ranked candidates in terms of the most pronounced potency against POP, AChE and BChE can be classified as 4d, 4u and 4v, bearing 4-methylbenzyl, (naphthalen-2-yl)methylene and 1-phenoxyethyl moieties, respectively. In vitro data were corroborated by detailed kinetic analysis of the selected lead molecules. 4d, 4u and 4v were also inspected for their potential to inhibit aggregation of two abberant proteins in AD, namely amyloid beta and tau, indicating their potential disease-modifying properties. To explain the results of our study, we carried out docking simulation to the active sites of the respective enzyme with the best berberine derivatives, along with QSAR study. We also investigated compounds' potential permeability through blood-brain barrier by applying parallel artificial membrane permeation assay and addressed their cytotoxicity profile.

NMDA Receptor Antagonists: Repositioning of Memantine as a Multitargeting Agent for Alzheimer's Therapy

Alzheimer's disease (AD) is a progressive neurodegenerative disease that causes problems with memory, thinking, and behavior. Currently, there is no drug that can reduce the pathological events of this degenerative disease but symptomatic relief is possible that can abate the disease condition. N-methyl-D-aspartate (NMDA) receptors exert a critical role for synaptic plasticity as well as transmission. Overstimulation of glutamate receptors, predominantly NMDA type, may cause excitotoxic effects on neurons and is recommended as a mechanism for neurodegeneration. Atypical activation of the NMDA receptor has been suggested for AD by synaptic dysfunction. NMDA receptor antagonists especially memantine block the NMDA receptor and can reduce the influx of calcium (Ca2+) ions into neuron, thus, toxic intracellular events are not activated. This review represents the role of NMDA receptors antagonists as potential therapeutic agents to reduce AD. Moreover, this review highlights the repositioning of memantine as a potential novel therapeutic multitargeting agent for AD.

Novel therapeutic strategies for Alzheimer's disease: Implications from cell-based therapy and nanotherapy

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease which leads to progressive dysfunction of cognition, memory and learning in elderly people. Common therapeutic agents are not only inadequate to suppress the progression of AD pathogenesis but also produce deleterious side effects; hence, development of alternative therapies is required to specifically suppress complications of AD. The current review provides a commentary on conventional as well as novel therapeutic approaches with an emphasis on stem cell and nano-based therapies for improvement and management of AD pathogenesis. According to our overview of the current literature, AD is a multi-factorial disorder with various pathogenic trajectories; hence, a multifunctional strategy to create effective neuroprotective agents is required to treat this disorder.

Cofilin 2 in Serum as a Novel Biomarker for Alzheimer's Disease in Han Chinese

The identification of biomarkers of Alzheimer’s disease (AD) is an important and urgent area of study, not only to aid in the early diagnosis of AD, but also to evaluate potentially new anti-AD drugs. The aim of this study was to explore cofilin 2 in serum as a novel biomarker for AD. The upregulation was observed in AD patients and different AD animal models compared to the controls, as well as in AD cell models. Memantine and donepezil can attenuate the upregulation of cofilin 2 expression in APP/PS1 mice. The serum levels of cofilin 2 in AD or mild cognitive impairment (MCI) patients were significantly higher compared to controls (AD: 167.9 ± 35.3 pg/mL; MCI: 115.9 ± 15.4 pg/mL; Control: 90.5 ± 27.1 pg/mL; p < 0.01). A significant correlation between cofilin 2 levels and cognitive decline was observed (r = –0.792; p < 0.001). The receiver operating characteristic curve (ROC) analysis showed the area under the curve (AUC) of cofilin 2 was 0.957, and the diagnostic accuracy was 80%, with 93% sensitivity and 87% specificity. The optimal cut-off value was 130.4 pg/ml. Our results indicate the possibility of serum cofilin 2 as a novel and non-invasive biomarker for AD. In addition, the expression of cofilin 2 was found to be significantly increased in AD compared to vascular dementia (VaD), and only an increased trend but not significant was detected in VaD compared to the controls. ROC analysis between AD and VaD showed that the AUC was 0.824, which could indicate a role of cofilin 2 as a biomarker in the differential diagnosis between AD and VaD.

Cholinesterase and Prolyl Oligopeptidase Inhibitory Activities of Alkaloids from Argemone platyceras (Papaveraceae)

Alzheimer's disease is an age-related, neurodegenerative disorder, characterized by cognitive impairment and restrictions in activities of daily living. This disease is the most common form of dementia with complex multifactorial pathological mechanisms. Many therapeutic approaches have been proposed. Among them, inhibition of acetylcholinesterase, butyrylcholinesterase, and prolyl oligopeptidase can be beneficial targets in the treatment of Alzheimer's disease. Roots, along with aerial parts of Argemone platyceras, were extracted with ethanol and fractionated on an alumina column using light petrol, chloroform and ethanol. Subsequently, repeated preparative thin-layer chromatography led to the isolation of (+)-laudanosine, protopine, (-)-argemonine, allocryptopine, (-)-platycerine, (-)-munitagine, and (-)-norargemonine belonging to pavine, protopine and benzyltetrahydroisoquinoline structural types. Chemical structures of the isolated alkaloids were elucidated by optical rotation, spectroscopic and spectrometric analysis (NMR, MS), and comparison with literature data. (+)-Laudanosine was isolated from A. platyceras for the first time. Isolated compounds were tested for human blood acetylcholinesterase, human plasma butyrylcholinesterase and recombinant prolyl oligopeptidase inhibitory activity. The alkaloids inhibited the enzymes in a dose-dependent manner. The most active compound (-)-munitagine, a pavine alkaloid, inhibited both acetylcholinesterase and prolyl oligopeptidase with IC50 values of 62.3 ± 5.8 µM and 277.0 ± 31.3 µM, respectively.

Nanotherapeutic strategies for the treatment of Alzheimer's disease

Alzheimer's disease (AD), the most common form of dementia, is now representing one of the largest unmet medical needs. However, no effective treatment is now available to impede the progression of AD or delay its onset. There are two major challenges for the development of effective therapy for AD. First, the exact cause for AD onset is still unknown. Second, brain drug delivery is significantly hindered by the blood-brain barrier (BBB). In this review, we will summarize the pathological understanding about AD and the related treatments, compare BBB and its effect on brain drug delivery under normal and AD conditions and review the nanotherapeutic strategies that have been developed for AD therapy in recent years.

Neuritogenic militarinone-inspired 4-hydroxypyridones target the stress pathway kinase MAP4K4

Progressive loss and impaired restoration of neuronal activity are hallmarks of neurological diseases, and new small molecules with neurotrophic activity are in high demand. The militarinone alkaloids and structurally simplified analogues with 4-hydroxy-2-pyridone core structure induce pronounced neurite outgrowth, but their protein target has not been identified. Reported herein is the synthesis of a militarinone-inspired 4-hydroxy-2-pyridone collection, its investigation for enhancement of neurite outgrowth, and the discovery of the stress pathway kinase MAP4K4 as a target of the discovered neuritogenic pyridones. The most potent 4-hydroxy-2-pyridone is a selective ATP-competitive inhibitor of MAP4K4 but not of the other stress pathway related kinases, as proven by biochemical analysis and by a crystal structure of the inhibitor in complex with MAP4K4. The findings support the notion that MAP4K4 may be a new target for the treatment of neurodegenerative diseases.

Pharmacokinetics of cotinine in rats: a potential therapeutic agent for disorders of cognitive function

BACKGROUND

Attention has been paid to cotinine (COT), one of the major metabolites of nicotine (NIC), for its pro-cognitive effects and potential therapeutic activities against Alzheimer's disease (AD) and other types of cognitive impairment. In order to facilitate pharmacological and toxicological studies on COT for its pro-cognitive activities, we conducted a pharmacokinetic (PK) study of COT in rats, providing important oral and intravenously (iv) PK information.

METHODS

In this study, plasma samples were obtained up to 48 h after COT was dosed to rats orally and iv at a dose of 3mg/kg. Plasma samples were prepared and analyzed using a sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) bioanalytical method, providing concentration profiles of COT and metabolites after oral and iv administrations.

RESULTS

The data were fitted into a one-compartment model and a two-compartment model for the oral and iv groups, respectively, providing important PK information for COT including PK profiles, half-life, clearance and bioavailability. The results suggested fast absorption, slow elimination and high bioavailability of COT in rats.

CONCLUSIONS

Several important facts about the PK properties in rats suggested COT could be a potential pro-cognitive agent. Information about the pharmacokinetics of COT in rats revealed in this study is of great importance for the future studies on COT or potential COT analogs as agents for improving cognition.

Concomitant use of acetylcholine esterase inhibitors and urinary antispasmodics among Finnish community-dwelling persons with Alzheimer disease

Concomitant use of acetylcholine esterase inhibitors (AChEIs) and anticholinergic drugs, such as urinary antispasmodics (UA), is generally considered as inappropriate because of their opposite pharmacological actions. However, prevalence and the duration or factors associated with concomitant use have not been previously studied among community-dwelling persons with Alzheimer disease (AD). The aim of this study was to examine the prevalence and duration of concomitant use of AChEIs and UAs among community-dwelling persons with AD and factors associated with concomitant use. Register-based data of the MEDALZ-2005 Study included all community-dwelling persons with clinically diagnosed AD at the end of year 2005 in Finland. Persons using AChEI drugs during the 4-year follow-up (2006-2009) were included in the present study (n = 20,442). Among AChEI users, 1576 persons used UA during the follow-up. Prevalence of concomitant use of AChEIs and UAs was 7.3% (n = 1491) during the 4-year follow-up. The median duration of concomitant use was 236 days. Factors associated with concomitant use were age younger than 80 years (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.08-1.34), male sex (OR, 1.16; 95% CI, 1.04-1.30), Parkinson disease (OR, 1.98; 95% CI, 1.55-2.52), diabetes (OR, 1.25; 95% CI, 1.08-1.45), and prostatic cancer (OR, 1.54; 95% CI, 1.13-2.09). Despite their antagonizing action, concomitant use of AChEIs and UAs was quite common among Finnish community-dwelling persons with AD. In addition, duration of concomitant use was comparatively long. It is recommended to consider some other options than UAs to treat urinary incontinence among persons with AD.

Synthesis, biological activity, and biopharmaceutical characterization of tacrine dimers as acetylcholinesterase inhibitors

Tacrine (THA), as the first approved acetylcholinesterase (AChE) inhibitors for the treatment of Alzheimer's disease (AD), has been extensively investigated in last seven decades. After dimerization of THA via a 7-carbon alkyl spacer, bis(7)-tacrine (B7T) showed much potent anti-AChE activity than THA. We here report synthesis, biological evaluation and biopharmaceutical characterization of six THA dimers referable to B7T. According to IC50 values, the in vitro anti-AChE activities of THA dimers were up to 300-fold more potent and 200-fold more selective than that of THA. In addition, the anti-AChE activities of THA dimers were found to be associated with the type and length of the linkage. All studied THA dimers showed much lower cytotoxicity than B7T, but like B7T, they demonstrated much lower absorptive permeabilities than that of THA on Caco-2 monolayer model. In addition, all THA dimers demonstrated significant efflux transport (efflux ratio >4), indicating that the limited permeability could be associated with the efflux transport during absorption process. Moreover, the dimer with higher Log P value was accompanied with higher permeability but lower aqueous solubility. A balanced consideration of activity, solubility, cytotoxicity and permeability should be conducted in selection of the potential candidates for further in vivo investigation.

Discovery of indanone derivatives as multi-target-directed ligands against Alzheimer's disease

A series of indanone derivatives were designed, synthesized, and tested using a variety of assays to assess their potential as anti-Alzheimer's disease (AD) agents. The investigations assessed the activities of the agents for the inhibition of cholinesterases (AChE and BuChE), the inhibition of amyloid beta (Aβ) self-assembly, and the catalysis of the disassembly of preformed Aβ oligomers and measured their antioxidant activities. Our results demonstrate that most of the synthesized compounds demonstrated good inhibitory activity against AChE with IC50 values in the nanomolar range. In particular, compounds 9 (IC50 = 14.8 nM) and 14 (IC50 = 18.6 nM) exhibited markedly higher inhibitory activities than tacrine and similar activities to donepezil. In addition, 9 and 14 significantly inhibited Aβ aggregation (inhibition rates of 85.5% and 83.8%, respectively), catalysed the disaggregation of Aβ fibrils generated by self-induced Aβ aggregation, and exhibited antioxidant activity. Furthermore, these two compounds can cross the blood-brain barrier (BBB) in vitro. These properties highlight the potential of these new compounds to be developed as multi-functional drugs for the treatment of Alzheimer's disease.

Antidementia drug use among community-dwelling individuals with Alzheimer's disease in Finland: a nationwide register-based study

The objective of this study was to investigate the prevalence of acetylcholinesterase inhibitor (AChEI) and memantine use, duration of treatment, concomitant use of these drugs, and factors associated with the discontinuation of AChEI therapy during 2006-2009. We utilized data from a nationwide sample of community-dwelling individuals with a clinically verified Alzheimer's disease diagnosed during the year 2005 (n=6858) as a part of the MEDALZ-2005 study. During the 4-year follow-up, 84% used AChEI and 47% used memantine. Altogether, 22% of the sample used both drugs concomitantly. The median duration of the first AChEI use period was 860 (interquartile range 295-1458) days and 1103 (interquartile range 489-1487) days for the total duration of AChEI use. Although 20% of the AChEI users discontinued the use during the first year, over half of them restarted later. The risk of discontinuation was higher for rivastigmine [hazard ratio 1.34 (confidence interval 1.22-1.48)] and galantamine users [hazard ratio 1.23 (confidence interval 1.15-1.37)] compared with donepezil users in the adjusted model. In conclusion, median time for AChEI use was over 3 years and every fifth Alzheimer's disease patient used AChEI and memantine concomitantly during the follow-up. The low rate of discontinuation is consistent with the Finnish Care Guideline but in contrast to the results reported from many other countries.

A 10-week memantine treatment in bipolar depression: a case report. Focus on depressive symptomatology, cognitive parameters and quality of life

Memantine and other glutamatergic agents have been currently investigated in some off-label indications due to glutamatergic involvement in several psychoneurological disorders. We assumed that memantine similarly to ketamine may positively influence mood, moreover having a potential to improve cognition and general quality of life. We report a case of a 49-year-old male hospitalized during a manic and a subsequent moderate depressive episode. After an ineffective use of lithium, olanzapine and antidepressive treatment with mianserin, memantine was added up to 20 mg per day for 10 weeks. The mental state was assessed using the Hamilton Depression Rating Scale, the Young Mania Rating Scale, the Hamilton Anxiety Scale, the Clinical Global Inventory, the World Health Organization Quality of Life Scale and psychological tests. After 10 weeks the patient achieved a partial symptomatic improvement in mood, anxiety and quality of sleep, but his activity remained insufficient. We also observed an improvement in the parameters of cognitive functioning and quality of life. There was neither significant mood variations during the memantine use nor mood changes after its termination. No significant side effects were noted during the memantine treatment. We conclude that using memantine in bipolar depression may improve mood, cognitive functioning and quality of life.

High performance liquid chromatographic fluorescence detection method for the quantification of rivastigmine in rat plasma and brain: application to preclinical pharmacokinetic studies in rats

A highly sensitive and selective high performance liquid chromatographic fluorescence detection method has been developed and validated for the quantification of rivastigmine in rat plasma and brain. Protein precipitation and one-step liquid–liquid extraction techniques were utilized for the extraction of RSM from brain and plasma, respectively, along with an internal standard. The chromatographic separation was achieved with a column inertsil ODS-3V and a mobile phase consisting of ammonium acetate buffer (20 mM, pH 4.5) and acetonitrile (76:24, v/v) delivered at a flow rate of 1 ml/min. The lower limit of quantitation for the developed method was 10 ng/mL for both matrices. The method was found to be accurate and reproducible and was successfully used to quantify levels of RSM in plasma and brain following intravenous administration of RSM in rats.

Comparative in vitro and in vivo evaluation of lipid based nanocarriers of Huperzine A

The purpose of the present investigation was to explore feasibility of nanocarrier based transdermal delivery of Huperzine A (HupA) for the treatment of Alzheimer's disease. For this investigation, microemulsion (ME), solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs) were formulated and characterized for physicochemical parameters. The pseudo-ternary phase diagrams for microemulsion region were developed using generally recognized as safe (GRAS) excipients. The SLNs and NLCs were prepared by microemulsion template technique. These nanodispersions were formulated into gels for transdermal application and evaluated for various physicochemical parameters. In vitro permeation profiles in rat skin exhibited zero-order kinetics. HupA loaded ME exhibited superior permeation than NLCs followed by SLNs and cumulative amount permeated after 24h was found to be 147.68±9.42 μg/cm(2), 129.11±32.76 μg/cm(2) and 10.74±0.68 μg/cm(2), respectively. Furthermore, optimized gels were subjected to primary skin irritation testing over a period of 48 h and were found to be safe for skin application. In vivo efficacy tested in scopolamine induced amnesia model indicated significant improvement in cognitive function in mice group treated with developed nanocarrier based formulations as compared to the control group.

Protective effect of galantamine against oxidative damage using human lymphocytes: a novel in vitro model

BACKGROUND AND AIMS

Neurodegenerative disorders such as Alzheimer's disease are characterized in the initial stages by an increase in reactive oxygen species that trigger apoptosis or programmed cell death. It has been suggested that the synthetic alkaloid galantamine may offer protection against this cell loss. This investigation sought to assess the protective effect of galantamine against oxidative damage induced by hydrogen peroxide (H2O2) using human lymphocytes cultured in vitro as a model.

METHODS

Cell death can be measured indirectly using cell viability testing with trypan blue. Determination of the galantamine concentrations used was made possible by the negative correlation found between galantamine concentration and average mitotic index (MI).

RESULTS

Average viability of lymphocytes treated with low and medium concentrations of galantamine was significantly higher than the control.

CONCLUSION

Galantamine does indeed demonstrate a protective capacity against cell damage induced by hydrogen peroxide. This finding supports the possible use of the drug in treatment of neurodegenerative diseases related to oxidative stress.

Sundown syndrome in persons with dementia: an update

"Sundowning" in demented individuals, as distinct clinical phenomena, is still open to debate in terms of clear definition, etiology, operationalized parameters, validity of clinical construct, and interventions. In general, sundown syndrome is characterized by the emergence or increment of neuropsychiatric symptoms such as agitation, confusion, anxiety, and aggressiveness in late afternoon, in the evening, or at night. Sundowning is highly prevalent among individuals with dementia. It is thought to be associated with impaired circadian rhythmicity, environmental and social factors, and impaired cognition. Neurophysiologically, it appears to be mediated by degeneration of the suprachiasmatic nucleus of the hypothalamus and decreased production of melatonin. A variety of treatment options have been found to be helpful to ameliorate the neuropsychiatric symptoms associated with this phenomenon: bright light therapy, melatonin, acetylcholinesterase inhibitors, N-methyl-d-aspartate receptor antagonists, antipsychotics, and behavioral modifications. To decrease the morbidity from this specific condition, improve patient's well being, lessen caregiver burden, and delay institutionalization, further attention needs to be given to development of clinically operational definition of sundown syndrome and investigations on etiology, risk factors, and effective treatment options.

Curing and caring: the work of primary care physicians with dementia patients

The symbolic framework guiding primary care physicians' (PCPs) practice is crucial in shaping the quality of care for those with degenerative dementia. Examining the relationship between the cure and care models in primary care offers a unique opportunity for exploring change toward a more holistic approach to health care. The aims of this study were to (a) explore how PCPs approach the care of patients with Alzheimer's disease (AD), and (b) describe how this care unfolds from the physicians' perspectives. This was a cross-sectional study of 40 PCPs who completed semistructured interviews as part of a dementia caregiving study. Findings show that PCPs recognize the limits of the cure paradigm and articulate a caring, more holistic model that addresses the psychosocial needs of dementia patients. However, caring is difficult to uphold because of time constraints, emotional burden, and jurisdictional issues. Thus, the care model remains secondary and temporary.

Donepezil in a narrow concentration range augments control and impaired by beta-amyloid peptide hippocampal LTP in NMDAR-independent manner

Acetylcholinesterase (AChE) inhibitor donepezil is widely used for the treatment of Alzheimer's disease (AD). The mechanisms of therapeutic effects of the drug are not well understood. The ability of donepezil to reverse a known pathogenic effect of β-amyloid peptide (Abeta), namely, the impairment of hippocampal long-term potentiation (LTP), was not studied yet. The goal of the present study was to study the influence of donepezil in 0.1-10 μM concentrations on control and Abeta-impaired hippocampal LTP. Possible involvement of N-methyl-D: -aspartate receptors (NMDARs) into mechanisms of donepezil action was also studied. LTP of population spike (PS) was studied in the CA1 region of rat hippocampal slices. Change of LTP by donepezil treatment had a bell-shaped dose-response curve. The drug in concentrations of 0.1 and 1 μM did not change LTP while in concentration of 0.5 μM significantly increased it, and in concentration of 5 and 10 μM suppressed LTP partially or completely. Abeta (200 nM) markedly suppressed LTP. Addition of 0.1, 0.5 or 1 μM donepezil to Abeta solution caused a restoration of LTP. N-methyl-D: -aspartate (NMDA) currents were studied in acutely isolated pyramidal neurons from CA1 region of rat hippocampus. Neither Abeta, nor 0.5 μM donepezil were found to change NMDA currents, while 10 μM donepezil rapidly and reversibly depressed it. Results suggest that donepezil augments control and impaired by Abeta hippocampal LTP in NMDAR-independent manner. In general, our findings extend the understanding of mechanisms of therapeutic action of donepezil, especially at an early stage of AD, and maybe taken into account while considering the possibility of donepezil overdose.

Organophosphates dysregulate dopamine signaling, glutamatergic neurotransmission, and induce neuronal injury markers in striatum

The neurological effects of organophosphate (OP) pesticides, commonly used on foods and in households, are an important public health concern. Furthermore, subclinical exposure to combinations of organophosphates is implicated in Gulf War illness. Here, we characterized the effects of the broadly used insecticide chlorpyrifos (CPF) on dopamine and glutamatergic neurotransmission effectors in corticostriatal motor/reward circuitry. CPF potentiated protein kinase A (PKA)-dependent phosphorylation of the striatal protein dopamine- and cAMP-regulated phosphoprotein of M(r) 32 kDa (DARPP-32) and the glutamate receptor 1 (GluR1) subunit of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in mouse brain slices. It also increased GluR1 phosphorylation by PKA when administered systemically. This correlated with enhanced glutamate release from cortical projections in rat striatum. Similar effects were induced by the sarin congener, diisopropyl fluorophosphate, alone or in combination with the putative neuroprotectant, pyridostigmine bromide and the pesticide N,N-diethyl-meta-toluamide (DEET). This combination, meant to mimic the neurotoxicant exposure encountered by veterans of the 1991 Persian Gulf War, also induced hyperphosphorylation of the neurofibrillary tangle-associated protein tau. Diisopropyl fluorophosphate and pyrodostigmine bromide, alone or in combination, also increased the aberrant activity of the protein kinase, Cdk5, as indicated by conversion of its activating cofactor p35 to p25. Thus, consistent with recent findings in humans and animals, organophosphate exposure causes dysregulation in the motor/reward circuitry and invokes mechanisms associated with neurological disorders and neurodegeneration.

Donepezil eliminates suppressive effects of β-amyloid peptide (1-42) on long-term potentiation in the hippocampus

β-Amyloid peptide 1-42 in a concentration of 200 nM impairs induction of long-term posttetanic potentiation of population spike in CA1 pyramidal neurons in rat hippocampal slices. Application of donepezil, a drug used for the treatment of Alzheimer disease, in a concentration of 1 μM eliminates the suppressive effect of β-amyloid peptide 1-42 on long-term posttenanic potentiation in the hippocampus.

Alzheimer's disease and age-related memory decline (preclinical)

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.

New perspective for the treatment of Alzheimer diseases: liposomal rivastigmine formulations

The aim of this study was to determine the transportations of rivastigmine containing from various liposome formulations through Madin Darby Canine Kidney (MDCK) cells monolayer and to compare the in vitro test results with in vivo. There is no other liposome formulation of rivastigmine and the transportations of rivastigmine through MDCK cell monolayers or related study available in the literature. Cytotoxicity (MTT) test was used to determine cell viabilities. The effect of sodium-taurocholate or dimethyl-beta-cyclodextrine as penetration enhancer was also investigated. Characterization and stability studies for liposome formulations were performed. Permeation experiments of rivastigmine were performed through MDCK cells and dialysis membrane. The kinetic of release from liposomes was also investigated. The highest apparent permeability coefficient (log. values) was obtained with sodium-taurocholate liposomes for -1.15 ± 0.16 for MDCK cell. Rivastigmine liposomes and solutions were also administered to mice orally and intraperitonally. Acetylcholinesterase (AChE) activity was determined by Ellman method. AChE% inhibition values were calculated for both blood and brain after administration of rivastigmine solution and liposomes. The highest AChE inhibition was observed for rivastigmine-sodium-taurocholate liposomes. Histological observations of the mice' brains were performed under transmission electron microscope (TEM). The histological results were also indicated and supported all these findings.

Neurogenesis in mouse models of Alzheimer's disease

The brains of the adult mouse and human possess neural stem cells (NSCs) that retain the capacity to generate new neurons through the process of neurogenesis. They share the same anatomical locations of stem cell niches in the brain, as well as the prominent feature of rostral migratory stream formed by neuroblasts migrating from the lateral ventricles towards the olfactory bulb. Therefore the mouse possesses some fundamental features that may qualify it as a relevant model for adult human neurogenesis. Adult born young hippocampal neurons in the mouse display the unique property of enhanced plasticity, and can integrate physically and functionally into existing neural circuits in the brain. Such crucial properties of neurogenesis may at least partially underlie the improved learning and memory functions observed in the mouse when hippocampal neurogenesis is augmented, leading to the suggestion that neurogenesis induction may be a novel therapeutic approach for diseases with cognitive impairments such as Alzheimer's disease (AD). Research towards this goal has benefited significantly from the use of AD mouse models to facilitate the understanding in the impact of AD pathology on neurogenesis. The present article reviews the growing body of controversial data on altered neurogenesis in mouse models of AD and attempts to assess their relative relevance to humans.

In vivo [(123)I]CNS-1261 binding to D-serine-activated and MK801-blocked NMDA receptors: A storage phosphor imaging study in rats

Disturbances of activity of the glutamatergic neurotransmitter system in the brain are present in many neuropsychiatric disorders. The N-methyl-D-aspartate (NMDA) receptor is the most abundant receptor of the glutamatergic system. In the neurodegenerative events of Alzheimer's disease, excessive activation of NMDA receptors may contribute to neuronal death. Inhibition of NMDA receptor activation may have neuroprotective effects and (semi)quantitative imaging of the activated system may help in the selection of patients for such inhibition therapies. In this study we evaluated [(123)I]CNS-1261 binding in the rat brain. This radiotracer binds in vivo to the MK801 binding site of activated NMDA receptors. To determine the optimal time point for ex vivo assessments after bolus injection [(123)I]CNS-1261 binding in rats, we performed a time course biodistribution study using dissection techniques. [(123)I]CNS-1261 binding was also studied in the rat brain using autoradiography by means of storage phosphor imaging, with prior facilitation of NMDA receptor activation by injection of the potent coagonist D-serine and after blocking of the NMDA receptor binding site by MK801 injection in D-serine pretreated rats. Measurements of [(123)I]CNS-1261 uptake matched the distribution of similar tracers for the MK801 binding site of the NMDA receptor and revealed an optimal time point of 2 h post injection for the assessment of tracer distribution in the rat brain. The blocking experiments indicated specific binding of [(123)I]CNS-1261 to NMDA receptors but also a considerable amount of nonspecific binding. Facilitation of NMDA receptor activation by D-serine did not result in an enhancement of binding of the radiotracer in the NMDA receptor-rich rat hippocampus compared to the untreated group, as measured by autoradiography. In conclusion, our study has shown that [(123)I]CNS-1261 binding is influenced by NMDA receptor availability. However, high nonspecific binding limits quantification and small changes in receptor availability are unlikely to be detected.

The paraoxonases: role in human diseases and methodological difficulties in measurement

Research into the paraoxonase (PON) gene family has flourished over the past few years. In the 1970s and 1980s, only PON1 was known, and the investigations were conducted, essentially, by toxicologists focusing on protection against organophosphate poisoning. Since then, two new members of the family, PON2 and PON3, have been identified, both being shown to play antioxidant and anti-inflammatory roles. Evidence exists indicating that the PON family is central to a wide variety of human illnesses such as cardiovascular disease, diabetes mellitus, metabolic syndrome, obesity, non-alcoholic steatohepatitis, and several mental disorders. However, research is hampered considerably by the methods currently available to measure the activity of these enzymes. In this review, we summarize the state of knowledge on PON biochemistry and function, the influence of genetic variations, and the involvement of PON in several diseases. The problems associated with PON measurement, such as sample acquisition, lack of reference methods, and variety of substrates, will be presented. Also, we cover some of the present lines of research and propose some others for future progress in this field.

Israeli lay persons' views on priority-setting criteria for Alzheimer's disease

AIM

The aim of this study was to assess Israeli lay persons' preferences for setting priorities for the care of Alzheimer's disease (AD).

BACKGROUND

As the knowledge about AD accumulates, and especially as more therapeutic and non-therapeutic interventions for its early diagnosis and treatment are developed, health-care costs associated with the disease rise dramatically. Therefore, setting priorities for funding these therapies, as well as other costs associated with AD is becoming an increasingly complex need.

METHODS

A convenience sample of 624 community-dwelling men and women participated in the study (mean age = 49, range = 20-90). Participants were asked how strongly they agreed or disagreed with 18 criteria that would be used to set priorities for the allocation of resources in the area of AD.

RESULTS

High-weight criteria included being a life-threatening condition and the benefit of treatment. Average-weight criteria included the severity of the disease, treatment costs and equity of access. The age of the patient also was highly rated. All other patient-related criteria were rated as low. Value orientations and education were the main variables associated with participants' preferences.

CONCLUSIONS

The lay public seems to endorse a multi-criteria decision process for the allocation of resources in the area of AD. Similar to other diseases--disease-related criteria were highly preferred. These preferences should be compared with those of other stakeholders such as clinicians and policy makers.

The process and organizational characteristics of memory clinics in Israel in 2007

We previously described the characteristics and activities of 25 memory clinics in Israel in 1998 using a mail survey. Questionnaires assessing the administrative structure of the clinics, patient characteristics, processes and methods used, and outcomes of the assessment were mailed again in 2007 to 35 memory clinics. Overall, the general operating characteristics of the clinics in 2007 were found to be similar to those reported in the previous survey conducted in 1998. The assessment process in 2007 was shorter than in 1998 (mean time=1.92 and 3.12 h, respectively), although both surveys were based on an interdisciplinary team, including a physician, a nurse and a social worker. However, in 2007 the teams were more wide-ranging. A wider variety of instruments were reported in the more recent survey. Most of the clinics in both surveys reported that family members were involved at all stages of the assessment. Medication treatment was the main outcome reported by the clinics in both surveys. There has been a development in the process and organizational characteristics of memory clinics in Israel over the years, probably as a consequence of the development of knowledge in the area of cognitive deterioration.

Pharmacokinetics and Bioequivalence Studies of Galantamine Hydrobromide Dispersible Tablet in Healthy Male Chinese Volunteers

A randomized, two-way, crossover study was conducted in 18 healthy male Chinese volunteers to compare pharmacokinetics profiles of galantamine hydrobromide dispersible tablet with that of conventional tablet. A single oral dose of 10 mg galantamine was administrated to each volunteer. Plasma concentrations of galantamine were determined by a validated high-performance liquid chromatography (HPLC) method with fluorescence detection, which allowed 1 ng/mL to be assayed as the lowest quantifiable concentration. From plasma concentrations, AUC(0-->t) (the area under the plasma concentration-time curve from time 0 to the last sampling time, 32 hr), AUC(0-->infinity) (the area under the plasma concentration-time curve from time 0 to infinity), t((1/2)) (elimination of half-life of the terminal log linear phase), C(max) (maximum plasma drug concentration) and T(max) (time to reach C(max)) were evaluated through noncompartmental pharmacokinetic analysis. AUC(0-->t) and AUC(0-->infinity) were calculated by the linear-log trapezoidal rule method. C(max) and T(max) were obtained directly from the plasma concentration-time curve. Analysis of variance was carried out using logarithmically transformed AUC(0-->t), AUC(0-->infinity) and C(max). As far as AUC(0-->t), AUC(0-->infinity) and C(max) were concerned, there was no statistically significant difference between the test and reference formulations. Ninety percent confidence intervals (90% CI) for the ratio of AUC(0-->t), AUC(0-->infinity) and C(max) values for the test and reference formulations were 100.4-107.8%, 99.0-107.2% and 87.5-111.3%, respectively. As the 90% CIs of AUC(0-->t), AUC(0-->infinity) and C(max) were entirely within 80-125%, two formulations were considered bioequivalent.

Neuroprotection in glaucoma: drug-based approaches

In recent years the focus of glaucoma research has shifted toward neuroprotection, as the traditional strategies of lowering intraocular pressure have been shown to be unable to prevent progressive vision loss in some glaucoma patients. As a result various neuroprotective drug-based approaches have been shown capable of reducing the death of retinal ganglion cells, which is the hallmark of glaucomatous optic neuropathy. There has been increasing evidence that glaucomatous neurodegeneration is analogous to other neurodegenerative diseases in the central nervous system, with recent work from our group elucidating a strong link between basic cellular processes in glaucoma and Alzheimer's disease. Additionally, there is a growing trend for using existing neuroprotective strategies in central nervous system diseases for the treatment of glaucoma. In fact, a trial treating patients with primary open-angle glaucoma with memantine, a drug approved for the treatment of Alzheimer's disease, has recently been completed. Results of this trial are not yet available. In this review, we will examine currently advocated neuroprotective drug-based strategies in the potential management of glaucoma.

Some treatment dilemmas in rapidly developing dementia: a case report

The treatment of rapidly deteriorating dementia is always very challenging. This case report describes a 78-year-old male patient with rapidly developing dementia treated successfully with orally disintegrating olanzapine, memantine, donepezil, omega-3 and vitamin-B complex. The prevailing fatalism and treatment nihilism regarding treatment of dementia should give way to more hope and optimism. Several important treatment dillemas in rapidly developing dementia are discussed.

Cholinergic treatments with emphasis on m1 muscarinic agonists as potential disease-modifying agents for Alzheimer's disease

The only prescribed drugs for treatment of Alzheimer's disease (AD) are acetylcholinesterase inhibitors (e.g., donepezil, rivastigmine, galantamine, and tacrine) and memantine, an NMDA antagonist. These drugs ameliorate mainly the symptoms of AD, such as cognitive impairments, rather than halting or preventing the causal neuropathology. There is currently no cure for AD and there is no way to stop its progression, yet there are numerous therapeutic approaches directed against various pathological hallmarks of AD that are extensively being pursued. In this context, the three major hallmark characteristics of AD (i.e., the CNS cholinergic hypofunction, formation of beta-amyloid plaques, and tangles containing hyperphosphorylated tau proteins) are apparently linked. Such linkages may have therapeutic implications, and this review is an attempt to analyze these versus the advantages and drawbacks of some cholinergic compounds, such as acetylcholinesterase inhibitors, M1 muscarinic agonists, M2 antagonists, and nicotinic agonists. Among the reviewed treatments, M1 selective agonists emerge, in particular, as potential disease modifiers.

Tetrahydrofurobenzofuran cymserine, a potent butyrylcholinesterase inhibitor and experimental Alzheimer drug candidate, enzyme kinetic analysis

Synaptic loss, particularly related to the forebrain cholinergic system, is considered to be an early event that leads to Alzheimer's disease (AD) and has led to the development of acetylcholinesterase inhibitors (AChE-Is) as the mainstay of treatment for several degenerative disorders that culminate in dementia. The primary dose-limiting toxicities of all clinically available AChE-Is are, similar to useful actions on cognition, cholinergically mediated and they ultimately limit the value of this drug class in achieving anything but symptomatic improvements. In addition, AChE levels in brain areas associated with AD decline with disease progression, which likely ultimately limits the therapeutic utility of this drug class. New research indicates that selective inhibition of butyrylcholinesterase (BuChE), a closely related enzyme that is markedly elevated in AD brain, increases acetylcholine (ACh) and augments cognition in rodents free of the characteristic undesirable actions of AChE-Is. BuChE inhibition hence represents an innovative treatment approach for AD, and agents are currently being synthesized to optimally achieve this. The novel compound, tetrahydrofurobenzofuran cymserine (THFBFC), is derived from our effort to produce a potent and BuChE-selective inhibitor as a candidate to test the hypothesis that BuChE-Is would be efficacious and better tolerated than AChE-Is in AD. Herein, we applied innovative enzyme kinetic analyses to characterize the quantitative interaction of THFBFC with human BuChE. These provided values for the agent's IC(50), together with specific new kinetic constants, such as K (T50), K (T1/2), R (I), (o)K (RT), (o)P(max), K(PT) and PT(1/2), to aid define target concentrations for clinical translation. Additional classical kinetic parameters, including K(i), K(m)or K(s), k(cat) or V(max) and V (mi) were also determined. THFBFC proved to be a potent competitive inhibitor of human BuChE and, like its isomer dihydrobenzodioxepine cymserine, is a potentially interesting AD drug candidate.

Molecular Neuroimaging: From Conventional to Emerging Techniques

The use of molecular imaging techniques in the central nervous system (CNS) has a rich history. Most of the important developments in imaging-such as computed tomography, magnetic resonance imaging, single photon emission computed tomography, and positron emission tomography-began with neuropsychiatric applications. These techniques and modalities were then found to be useful for imaging other organs involved with various disease processes. Molecular imaging of the CNS has enabled scientists and researchers to understand better the basic biology of brain function and the way in which various disease processes affect the brain. Unlike other organs, the brain is not easily accessible, and it has a highly selective barrier at the endothelial cell level known as the blood-brain barrier. Furthermore, the brain is the most complex cellular network known to exist. Various neurotransmitters act in either an excitatory or an inhibitory fashion on adjacent neurons through a multitude of mechanisms. The various neuronal systems and the myriad of neurotransmitter systems become altered in many diseases. Some of the most devastating diseases, including Alzheimer disease, Parkinson disease, brain tumors, psychiatric disease, and numerous degenerative neurologic diseases, affect only the brain. Molecular neuroimaging will be critical to the future understanding and treatment of these diseases. Molecular neuroimaging of the brain shows tremendous promise for clinical application. In this article, the current state and clinical applications of molecular neuroimaging will be reviewed.

Neuropsychological deficits in frontotemporal dementia and Alzheimer's disease: a meta-analytic review

We sought to identify the cognitive tests that best discriminate between Alzheimer's disease (AD) and frontotemporal dementia (FTD). A comprehensive search of all studies examining the cognitive performance of persons diagnosed with AD and FTD, published between 1980 and 2006, was conducted. Ninety-four studies were identified, comprising 2936 AD participants and 1748 FTD participants. Weighted Cohen's d effect sizes, percentage overlap statistics, confidence intervals and fail-safe Ns were calculated for each cognitive test that was used by two or more studies. The most discriminating cognitive tests were measures of orientation, memory, language, visuomotor function and general cognitive ability. Although there were large and significant differences between groups on these measures, there was substantial overlap in the scores of the AD and FTD groups. Age, education, years since diagnosis and diagnostic criteria did not significantly contribute to the group differences. Given the large overlap in the test performance of persons diagnosed with AD and FTD, cognitive tests should be used cautiously and in conjunction with a medical history, behavioural observations, imaging and information from relatives when making differential diagnoses.

Development of a high performance liquid chromatography-tandem mass method for determination of bis(7)-tacrine, a promising anti-Alzheimer's dimer, in rat blood

An analytical method using on-line high performance liquid chromatography-tandem mass spectrometry with electrospray ionization was developed and applied for the quantification of bis(7)-tacrine (B7T) in rat blood. B7T and pimozide (internal standard, IS) were extracted in a single step from 100 microl of alkalized blood with ethyl acetate. Analytes were separated using an Extend C-18 column at 25 degrees C. The elution was achieved isocratically with a mobile phase composed of 0.05% aqueous formic acid and acetonitrile (60:40, v/v) at a flow rate of 0.35 ml/min. Quantification was achieved by monitoring the selected ions at m/z 247 for B7T and m/z 462-->m/z 328 for pimozide. Retention times were 1.45 and 2.23 min for B7T and IS, respectively. Calibration curves were linear in the range from 86.4 to 2160.0 ng/ml. The established method is rapid, selective and sensitive for the identification and quantification of B7T in biological samples. The assay is accurate (bias <10%) and reproducible (intra- and inter-day variation <10%), with detection and quantification limit of 3.6 and 42.3 ng/ml, respectively. Furthermore, it was successfully applied for the pharmacokinetic measurement of B7T in rat with a single intravenous administration at 0.3mg/kg.