Atorvastatin and pitavastatin improve cognitive function and reduce senile plaque and phosphorylated tau in aged APP mice

Behavioral and Metabolic Effects of ABCG4 KO in the APPswe,Ind (J9) Mouse Model of Alzheimer's Disease

The pathogenesis of Alzheimer's disease (AD) is complex and involves an imbalance between production and clearance of amyloid-ß peptides (Aß), resulting in accumulation of Aß in senile plaques. Hypercholesterolemia is a major risk factor for developing AD, with cholesterol shown to accumulate in senile plaques and increase production of Aß. ABCG4 is a member of the ATP-binding cassette transporters predominantly expressed in the CNS and has been suggested to play a role in cholesterol and Aß efflux from the brain. In this study, we bred Abcg4 knockout (KO) with the APPSwe,Ind (J9) mouse model of AD to test the hypothesis that loss of Abcg4 would exacerbate the AD phenotype. Unexpectedly, no differences were observed in novel object recognition (NOR) and novel object placement (NOP) behavioral tests, or on histologic examinations of brain tissues for senile plaque numbers. Furthermore, clearance of radiolabeled Aß from the brains did not differ between Abcg4 KO and control mice. Metabolic testing by indirect calorimetry, glucose tolerance test (GTT), and insulin tolerance test (ITT) were also mostly similar between groups with only a few mild metabolic differences noted. Overall, these data suggest that the loss of ABCG4 did not exacerbate the AD phenotype.

Protective Effects Against Dementia Undergo Different Statin Type, Intensity, and Cumulative Dose in Older Adult Type 2 Diabetes Mellitus Patients

OBJECTIVES

This study investigated the relationship between statin use and dementia risk in older adults with type 2 diabetes (T2DM). It also assessed the impact of various statin types, dosage intensity, and cumulative doses on dementia risk.

DESIGN

Employing the inverse probability of treatment weighting (IPTW) Cox hazards model, this research explored the influence of statin utilization on dementia incidence.

SETTING AND PARTICIPANTS

The study included older adult T2DM patients aged 60 years or older who received statins (case group) and those who did not (control group) during the follow-up period.

METHODS

The IPTW Cox hazards model quantified the association between statin use and dementia incidence. Subgroup analyses investigated different statin types, usage intensity, and cumulative dose-dependent relationships with dementia risk, measured by adjusted hazard ratios (aHRs) with corresponding 95% CIs.

RESULTS

Statin users experienced a significant reduction in dementia risk (aHR: 0.47, 95% CI: 0.46-0.48). Subgroup analysis using IPTW Cox regression revealed varying dementia incidence reductions among users of different statin types, with aHRs (95% CIs) ranging from 0.09 to 0.69. Multivariate analyses unveiled a dose-dependent relationship, showing reduced dementia incidence based on cumulative defined daily doses (cDDDs) per year. The corresponding aHRs (95% CIs) were 0.20 to 0.72 across quartiles 4 to 1 of cDDD-years, with a significant trend (P < .001). The optimal daily statin use was 0.88 defined daily doses (DDDs), associated with the lowest dementia risk.

CONCLUSIONS AND IMPLICATIONS

Statins significantly reduced dementia risk in older adult T2DM patients. Higher cumulative defined daily doses (cDDD-years) were linked to more substantial risk reductions. This research underscores the clinical benefits of statin use in preventing dementia in this population and calls for further investigation into the underlying mechanisms. It also raises the possibility of influencing policy decisions to manage dementia risk in this vulnerable group.

Tocovid Attenuated Oxidative Stress and Cognitive Decline by Inhibiting Amyloid-β-Induced NOX2 Activation in Alzheimer's Disease Mice

Background

NADPH oxidase 2 (NOX2) is an important source of reactive oxygen species (ROS). Activated NOX2 may contribute to Alzheimer's disease (AD). Our previous studies showed that a novel vitamin E mixture, Tocovid, had potential neuroprotective effects in a stroke mice model and an AD cell model.

Objective

The aim of this study was two-fold: to assess whether long-term Tocovid treatment can regulate NOX2, and the therapeutic effects of long-term administration of Tocovid to an AD mice model.

Methods

Therapeutic effects of long-term administration of Tocovid (200 mg/kg /day) on an Aβ-overexpressed transgenic AD mice model (APP23, n = 8) was investigated. The therapeutic effect of Tocovid in 16-month-old mice compared with the no-treatment APP23 group (n = 9) was assessed.

Results

Tocovid treatment strongly improved motor and memory deficits of APP23 mice by attenuating NOX2 expression, oxidative stress, neuroinflammation, neurovascular unit dysfunction, synaptic alteration, and Aβ deposition after 16 months.

Conclusion

These findings suggest that NOX2 is a potential target in AD pathology. Long-term administration of Tocovid may be a promising candidate for AD treatment.

Angiotensin-converting enzyme inhibitors and statins therapies-induced changes in omics profiles in humans and transgenic tau mice

BACKGROUND

Hypertension and hyperlipidemia are considered risk factors for Alzheimer's disease (AD) and other related dementias. Clinically approved medications typically prescribed to manage these conditions have shown an association with reduced risk of developing AD and could be explored as potential repurposed therapeutics.

OBJECTIVE

We aimed to explore the effects of the pharmacological treatment with angiotensin-converting enzyme inhibitors (ACEI) and statins (STAT) on AD-related neuropathology and the potential benefits of their concurrent use.

METHODS

We investigated the effect of ACEI, STAT or combination of both by exploring the transcriptomic, proteomic and tau pathology profiles after treatment in both human patients and in P301S transgenic mice (PS19) modeling tauopathies and AD. We performed bioinformatic analysis of enriched pathways after treatment.

RESULTS

Proteomics and transcriptomics analysis revealed proteins and genes whose expression is significantly changed in subjects receiving treatment with ACEI, STAT or combined drugs. In mice, treatment with the ACEI lisinopril significantly decreased brain levels of total tau (Tau) and phosphorylated tau (pTau)-181, while the STAT atorvastatin significantly reduced the levels of pTau-396. The combined therapy with lisinopril and atorvastatin significantly decreased Tau. Moreover, brain levels of lisinopril were negatively correlated with Tau. Among the others, CD200, ADAM22, BCAN and NCAM1 were significantly affected by treatments in both human subjects and transgenic mice.

CONCLUSIONS

Our findings provide significant information that may guide future investigation of the potential use of ACEI, STAT, or the combination of the two drug classes as repurposed therapies or preventive strategies for AD and other neurodegenerative diseases.

Behavioral and metabolic and effects of ABCG4 KO in the APPswe,Ind (J9) mouse model of Alzheimer's disease

The pathogenesis of Alzheimer's disease (AD) is complex and involves an imbalance between production and clearance of amyloid-ß peptides (Aß), resulting in accumulation of Aß in senile plaques. Hypercholesterolemia is a major risk factor for developing AD, with cholesterol shown to accumulate in senile plaques and increase production of Aß. ABCG4 is a member of the ATP-binding cassette transporters predominantly expressed in the CNS, and has been suggested to play a role in cholesterol and Aß efflux from the brain. In this study, we bred Abcg4 knockout (KO) with the APPSwe,Ind (J9) mouse model of AD to test the hypothesis that loss of Abcg4 would exacerbate the AD phenotype. Unexpectedly, no differences were observed in Novel object recognition (NOR) and Novel object placement (NOP) behavioral tests, or on histologic examinations of brain tissues for senile plaque numbers. Furthermore, clearance of radiolabeled Aß from the brains did not differ between Abcg4 KO and control mice. Metabolic testing by indirect calorimetry, glucose tolerance test (GTT) and insulin tolerance test (ITT), were also mostly similar between groups with only a few mild metabolic differences noted. Overall these data suggest that the loss of ABCG4 did not exacerbate the AD phenotype.

Pitavastatin protects against neomycin-induced ototoxicity through inhibition of endoplasmic reticulum stress

Irreversible injury to inner ear hair cells induced by aminoglycoside antibiotics contributes to the formation of sensorineural hearing loss. Pitavastatin (PTV), a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, has been reported to exert neuroprotective effects. However, its role in aminoglycoside-induced hearing loss remains unknown. The objectives of this study were to investigate the beneficial effects, as well as the mechanism of action of PTV against neomycin-induced ototoxicity. We found that PTV remarkably reduced hair cell loss in mouse cochlear explants and promoted auditory HEI-OC1 cells survival after neomycin stimulation. We also observed that the auditory brainstem response threshold that was increased by neomycin was significantly reduced by pretreatment with PTV in mice. Furthermore, neomycin-induced endoplasmic reticulum stress in hair cells was attenuated by PTV treatment through inhibition of PERK/eIF2α/ATF4 signaling. Additionally, we found that PTV suppressed the RhoA/ROCK/JNK signal pathway, which was activated by neomycin stimulation in HEI-OC1 cells. Collectively, our results showed that PTV might serve as a promising therapeutic agent against aminoglycoside-induced ototoxicity.

Clinical and Pathological Benefits of Scallop-Derived Plasmalogen in a Novel Mouse Model of Alzheimer’s Disease with Chronic Cerebral Hypoperfusion

Background: The oral ingestion of scallop-derived plasmalogen (sPlas) significantly improved cognitive function in Alzheimer’s disease (AD) patients. Objective: However, the effects and mechanisms of sPlas on AD with chronic cerebral hypoperfusion (CCH), a class of mixed dementia contributing to 20–30% among the dementia society, were still elusive. Methods: In the present study, we applied a novel mouse model of AD with CCH to investigate the potential effects of sPlas on AD with CCH. Results: The present study demonstrated that sPlas significantly recovered cerebral blood flow, improved motor and cognitive deficits, reduced amyloid-β pathology, regulated neuroinflammation, ameliorated neural oxidative stress, and inhibited neuronal loss in AD with CCH mice at 12 M. Conclusion: These findings suggest that sPlas possesses clinical and pathological benefits for AD with CCH in the novel model mice. Furthermore, sPlas could have promising prevention and therapeutic effects on patients of AD with CCH.

The Calcium-free form of Atorvastatin inhibits amyloid-β(1-42) aggregation in vitro

Alzheimer's disease is characterized by the presence of extraneuronal amyloid plaques composed of amyloid-beta (Aβ) fibrillar aggregates in the brains of patients. In mouse models, it has previously been shown that atorvastatin (Ator), a cholesterol-lowering drug, has some reducing effect on the production of cerebral Aβ. A meta-analysis on humans showed moderate effects in the short term but no improvement in the Alzheimer's Disease Assessment Scale—Cognitive Subscale behavioral test. Here, we explore a potential direct effect of Ator on Aβ42 aggregation. Using NMR-based monomer consumption assays and CD spectroscopy, we observed a promoting effect of Ator in its original form (Ator-calcium) on Aβ42 aggregation, as expected because of the presence of calcium ions. The effect was reversed when applying a CaCO₃-based calcium ion scavenging method, which was validated by the aforementioned methods as well as thioflavin-T fluorescence assays and transmission electron microscopy. We found that the aggregation was inhibited significantly when the concentration of calcium-free Ator exceeded that of Aβ by at least a factor of 2. The ¹H–¹⁵N heteronuclear single quantum correlation and saturation-transfer difference NMR data suggest that calcium-free Ator exerts its effect through interaction with the ¹⁶KLVF¹⁹ binding site on the Aβ peptide via its aromatic rings as well as hydroxyl and methyl groups. On the other hand, molecular dynamics simulations confirmed that the increasing concentration of Ator is necessary for the inhibition of the conformational transition of Aβ from an α-helix-dominant to a β-sheet-dominant structure.

Protective Effect of Rivaroxaban Against Amyloid Pathology and Neuroinflammation Through Inhibiting PAR-1 and PAR-2 in Alzheimer's Disease Mice

BACKGROUND

Recent studies have revealed that atrial fibrillation (AF) patients have a high risk of developing cognitive impairment, vascular dementia, and Alzheimer's disease (AD). Some reports suggest that the application of oral anticoagulant with an appropriate dose may have a preventive effect on AD. However, which oral anticoagulant drug is more appropriate for preventing AD and the underlying mechanism(s) is still unknown.

OBJECTIVE

The aim of the present study was to assess the treatment effect of rivaroxaban administration as well as investigate the roles of PAR-1 and PAR-2 in the AD + CAA mice model.

METHODS

In the present study, we compared a traditional oral anticoagulant, warfarin, and a direct oral anticoagulant (DOAC), rivaroxaban, via long-term administration to an AD with cerebral amyloid angiopathy (CAA) mice model.

RESULTS

Rivaroxaban treatment attenuated neuroinflammation, blood-brain barrier dysfunction, memory deficits, and amyloid-β deposition through PAR-1/PAR-2 inhibition in the AD + CAA mice model compared with warfarin and no-treatment groups.

CONCLUSION

The present study demonstrates that rivaroxaban can attenuate AD progress and can be a potential choice to prevent AD.

A comprehensive review on the lipid and pleiotropic effects of pitavastatin

The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, or statins, are administered as first line therapy for hypercholesterolemia, both in primary and secondary prevention. There is a growing body of evidence showing that beyond their lipid-lowering effect, statins have a number of additional beneficial properties. Pitavastatin is a unique lipophilic statin with a strong effect on lowering plasma total cholesterol and triacylglycerol. It has been reported to have pleiotropic effects such as decreasing inflammation and oxidative stress, regulating angiogenesis and osteogenesis, improving endothelial function and arterial stiffness, and reducing tumor progression. Based on the available studies considering the risk of statin-associated muscle symptoms it seems to be also the safest statin. The unique lipid and non-lipid effects of pitavastatin make this molecule a particularly interesting option for the management of different human diseases. In this review, we first summarized the lipid effects of pitavastatin and then strive to unravel the diverse pleiotropic effects of this molecule.

Involvement of H2 S, NO and BDNF-TrkB signalling pathway in the protective effects of simvastatin against pentylenetetrazole-induced kindling and cognitive impairments in mice

Cognitive dysfunction was observed in pentylenetetrazole (PTZ)-kindled mice. The potential effectiveness of simvastatin (SIM) on PTZ-induced kindling and cognitive impairments in mice was evaluated. The influence of SIM on hydrogen sulphide (H2 S), nitric oxide (NO), reactive aldehydes and brain-derived neurotrophic factor/tyrosine receptor kinase B (BDNF-TrkB) signalling was also investigated. Kindling and cognitive impairments in mice were induced by 12 ip injections of PTZ (35 mg/kg) once every alternate day. The levels of reactive aldehydes and nitrite were increased while H2 S was decreased in PTZ-treated mice. These results were accompanied by a reduction in the gene expression of aldehyde dehydrogenase 2, cystathionine β-synthase, BDNF and TrkB. In PTZ-kindled mice, a rise in brain inducible nitric oxide synthase protein expression associated with histopathological changes was observed. SIM administration (1, 5 and 10 mg/kg, daily orally) along with alternate day of PTZ (35 mg/kg) resulted in a decrease in PTZ-induced kindling with a dose-dependent improvement in cognitive function. SIM (10 mg/kg) prevented, to variable extent, the disturbances associated with PTZ-kindled mice with cortical, cerebellar and hippocampal structural improvement. These results suggested that SIM triggers multiple mechanisms that improve cognitive function in PTZ-kindled mice through modulation of oxidative stress, H2 S, NO and BDNF-TrkB signalling pathway.

Harnessing endophenotypes and network medicine for Alzheimer's drug repurposing

Following two decades of more than 400 clinical trials centered on the "one drug, one target, one disease" paradigm, there is still no effective disease-modifying therapy for Alzheimer's disease (AD). The inherent complexity of AD may challenge this reductionist strategy. Recent observations and advances in network medicine further indicate that AD likely shares common underlying mechanisms and intermediate pathophenotypes, or endophenotypes, with other diseases. In this review, we consider AD pathobiology, disease comorbidity, pleiotropy, and therapeutic development, and construct relevant endophenotype networks to guide future therapeutic development. Specifically, we discuss six main endophenotype hypotheses in AD: amyloidosis, tauopathy, neuroinflammation, mitochondrial dysfunction, vascular dysfunction, and lysosomal dysfunction. We further consider how this endophenotype network framework can provide advances in computational and experimental strategies for drug-repurposing and identification of new candidate therapeutic strategies for patients suffering from or at risk for AD. We highlight new opportunities for endophenotype-informed, drug discovery in AD, by exploiting multi-omics data. Integration of genomics, transcriptomics, radiomics, pharmacogenomics, and interactomics (protein-protein interactions) are essential for successful drug discovery. We describe experimental technologies for AD drug discovery including human induced pluripotent stem cells, transgenic mouse/rat models, and population-based retrospective case-control studies that may be integrated with multi-omics in a network medicine methodology. In summary, endophenotype-based network medicine methodologies will promote AD therapeutic development that will optimize the usefulness of available data and support deep phenotyping of the patient heterogeneity for personalized medicine in AD.

Clinical and Pathological Benefits of Edaravone for Alzheimer's Disease with Chronic Cerebral Hypoperfusion in a Novel Mouse Model

Alzheimer's disease (AD) and chronic cerebral hypoperfusion (CCH) often coexist in dementia patients in aging societies. The hallmarks of AD including amyloid-β (Aβ)/phosphorylated tau (pTau) and pathology-related events such as neural oxidative stress and neuroinflammation play critical roles in pathogenesis of AD with CCH. A large number of lessons from failures of drugs targeting a single target or pathway on this so complicated disease indicate that disease-modifying therapies targeting multiple key pathways hold potent potential in therapy of the disease. In the present study, we used a novel mouse model of AD with CCH to investigate a potential therapeutic effect of a free radical scavenger, Edaravone (EDA) on AD with CCH via examining motor and cognitive capacity, AD hallmarks, neural oxidative stress, and neuroinflammation. Compared with AD with CCH mice at 12 months of age, EDA significantly improved motor and cognitive deficits, attenuated neuronal loss, reduced Aβ/pTau accumulation, and alleviated neural oxidative stress and neuroinflammation. These findings suggest that EDA possesses clinical and pathological benefits for AD with CCH in the present mouse model and has a potential as a therapeutic agent for AD with CCH via targeting multiple key pathways of the disease pathogenesis.

Pleiotropic effects of statins on brain cells

Starting with cholesterol homeostasis, the first part of the review addresses various aspects of cholesterol metabolism in neuronal and glial cells and the mutual crosstalk between the two cell types, particularly the transport of cholesterol from its site of synthesis to its target loci in neuronal cells, discussing the multiple mechanistic aspects and transporter systems involved. Statins are next analyzed from the point of view of their chemical structure and its impingement on their pharmacological properties and permeability through cell membranes and the blood-brain barrier in particular. The following section then discusses the transcriptional effects of statins and the changes they induce in brain cell genes associated with a variety of processes, including cell growth, signaling and trafficking, uptake and synthesis of cholesterol. We review the effects of statins at the cellular level, analyzing their impact on the cholesterol composition of the nerve and glial cell plasmalemma, neurotransmitter receptor mobilization, myelination, dendritic arborization of neurons, synaptic vesicle release, and cell viability. Finally, the role of statins in disease is exemplified by Alzheimer and Parkinson diseases and some forms of epilepsy, both in animal models and in the human form of these pathologies.

Cognitive Function Assessment in Patients on Moderate- or High-Intensity Statin Therapy

Background

Cardiovascular diseases are the leading cause of death in the USA. Statin therapy reduces cardiovascular events significantly. Cognitive impairment has been reported with statin therapy but there is a lack of consensus. We analyzed the cognitive functions of adult patients who were on moderate-intensity statin therapy (MIST) or high-intensity statin therapy (HIST).

Methods

A total of 213 patients underwent cognitive assessment testing. Cognitive function scores were correlated with the durations of statin therapy, age, and level of education by using Pearson correlation. Independent t-test was used to compare the mean cognitive function score to the gender, race, type of statin therapy, and comorbid conditions.

Results

Mean age of all the patients was 55.4 years. Majority of the patients (66.2%) were on MIST while the rest (33.8%) were on HIST. Cognitive impairment was observed in 17.8% of the studied patients. A total of 41.7% of the patients in the HIST group and 5.7% in the MIST group had cognitive impairment (P < 0.001). There was no correlation between cognitive function score and age (r = -0.106), weakly positive correlation between the level of education and cognitive function score (r = 0.252), and weakly negative correlation between the duration of statin therapy and cognitive function score (r = -0.283). In the group of patients on HIST with cognitive impairment, the proportion of patients on atorvastatin 40 - 80 mg was significantly higher than the proportion of patients on rosuvastatin 20 - 40 mg (66.7% vs. 33.3%; P < 0.05). In the group of patients on MIST with cognitive impairment, atorvastatin 10 - 20 mg was the most commonly used statin therapy (50%), followed by rosuvastatin 10 mg (25%), simvastatin 20 - 40 mg (12.5%) and pravastatin 40 - 80 mg (12.5%).

Conclusions

We found a significantly higher association of cognitive impairment in patients who were on MIST or HIST compared to the general population. We found no correlation between cognitive function score and age, weakly positive correlation between the level of education and cognitive function score, and weakly negative correlation between the duration of statin therapy and cognitive function score. HIST was associated with a higher frequency of cognitive impairment compared to the MIST.

Association of Hypercholesterolemia with Alzheimer's Disease Pathology and Cerebral Amyloid Angiopathy

BACKGROUND

Animal studies have shown that diet-induced hypercholesterolemia (HC) increases amyloid-β (Aβ) accumulation and accelerates Alzheimer's disease (AD) pathology. However, the association of HC with AD in human studies has not been consistently established.

OBJECTIVE

We aimed to investigate the relationship between HC and risk of AD neuropathology in a large national sample with autopsies.

METHODS

This study used neuropathological and clinical data from 3,508 subjects from the National Alzheimer's Coordinating Center (NACC) who underwent autopsies from 2005 to 2017. Demographic and clinical characteristics, as well as neuropathological outcomes were compared between subjects with and without HC. Associations between HC and AD neuropathology were examined by multivariate ordinal logistic regressions adjusting for potential confounders.

RESULTS

HC was not associated with any AD neuropathology in a model only adjusting for demographic variables. However, HC was significantly associated with higher CERAD neuritic and diffuse plaque burden, higher Braak stage, and more severe cerebral amyloid angiopathy when analyzed in a multivariate model controlling for comorbidities. Additional adjusting for cerebrovascular conditions did not diminish these associations. The association between HC and increased risk of neuritic plaques weakened but remained significant even after controlling for ApoE genotype.

CONCLUSION

This study suggested that HC was associated with increased severity of AD pathology, which could only be partially accounted for by ApoE genotype. The associations were not mediated by cerebrovascular conditions.

Centella Asiatica Improves Memory and Promotes Antioxidative Signaling in 5XFAD Mice

Centella asiatica (CA) herb is a traditional medicine, long reputed to provide cognitive benefits. We have reported that CA water extract (CAW) treatment improves cognitive function of aged Alzheimer’s disease (AD) model Tg2576 and wild-type (WT) mice, and induces an NRF2-regulated antioxidant response in aged WT mice. Here, CAW was administered to AD model 5XFAD female and male mice and WT littermates (age: 7.6 +/− 0.6 months), and object recall and contextual fear memory were tested after three weeks treatment. CAW’s impact on amyloid-β plaque burden, and markers of neuronal oxidative stress and synaptic density, was assessed after five weeks treatment. CAW antioxidant activity was evaluated via nuclear transcription factor (erythroid-derived 2)-like 2 (NRF2) and NRF2-regulated antioxidant response element gene expression. Memory improvement in both genders and genotypes was associated with dose-dependent CAW treatment without affecting plaque burden, and marginally increased synaptic density markers in the hippocampus and prefrontal cortex. CAW treatment increased Nrf2 in hippocampus and other NRF2 targets (heme oxygenase-1, NAD(P)H quinone dehydrogenase 1, glutamate-cysteine ligase catalytic subunit). Reduced plaque-associated SOD1, an indicator of oxidative stress, was observed in the hippocampi and cortices of CAW-treated 5XFAD mice. We postulate that CAW treatment leads to reduced oxidative stress, contributing to improved neuronal health and cognition.

Amyloid-β-independent regulators of tau pathology in Alzheimer disease

The global epidemic of Alzheimer disease (AD) is worsening, and no approved treatment can revert or arrest progression of this disease. AD pathology is characterized by the accumulation of amyloid-β (Aβ) plaques and tau neurofibrillary tangles in the brain. Genetic data, as well as autopsy and neuroimaging studies in patients with AD, indicate that Aβ plaque deposition precedes cortical tau pathology. Because Aβ accumulation has been considered the initial insult that drives both the accumulation of tau pathology and tau-mediated neurodegeneration in AD, the development of AD therapeutics has focused mostly on removing Aβ from the brain. However, striking preclinical evidence from AD mouse models and patient-derived human induced pluripotent stem cell models indicates that tau pathology can progress independently of Aβ accumulation and arises downstream of genetic risk factors for AD and aberrant metabolic pathways. This Review outlines novel insights from preclinical research that implicate apolipoprotein E, the endocytic system, cholesterol metabolism and microglial activation as Aβ-independent regulators of tau pathology. These factors are discussed in the context of emerging findings from clinical pathology, functional neuroimaging and other approaches in humans. Finally, we discuss the implications of these new insights for current Aβ-targeted strategies and highlight the emergence of novel therapeutic strategies that target processes upstream of both Aβ and tau.

Clinical and Pathological Benefit of Twendee X in Alzheimer's Disease Transgenic Mice with Chronic Cerebral Hypoperfusion

BACKGROUND

Multiple pathogeneses are involved in Alzheimer's disease (AD), such as amyloid-β accumulation, neuroinflammation, and oxidative stress. The pathological impact of chronic cerebral hypoperfusion on Alzheimer's disease is still poorly understood.

METHODS

APP23 mice were implanted to bilateral common carotid arteries stenosis with ameroid constrictors for slowly progressive chronic cerebral hypoperfusion (CCH). The effects of the administration of Twendee X (TwX) were evaluated by behavioral analysis, immunohistochemical analysis, and immunofluorescent histochemistry.

RESULTS

In the present study, chronic cerebral hypoperfusion, which is commonly found in aged Alzheimer's disease, significantly exacerbated motor dysfunction of APP23 mice from 5 months and cognitive deficit from 8 months of age, as well as neuronal loss, extracellular amyloid-β plaque and intracellular oligomer formations, and amyloid angiopathy at 12 months. Severe upregulations of oxidative markers and inflammatory markers were found in the cerebral cortex, hippocampus, and thalamus at 12 months. Twendee X treatment (20 mg/kg/d, from 4.5 to 12 months) substantially rescued the cognitive deficit and reduced the above amyloid-β pathology and neuronal loss, alleviated neuroinflammation and oxidative stress.

CONCLUSIONS

The present findings suggested a potential therapeutic benefit of Twendee X for Alzheimer's disease with chronic cerebral hypoperfusion.

Prostaglandin A1 Inhibits the Cognitive Decline of APP/PS1 Transgenic Mice via PPARγ/ABCA1-dependent Cholesterol Efflux Mechanisms

Prostaglandins (PGs) are early and key contributors to chronic neurodegenerative diseases. As one important member of classical PGs, PGA1 has been reported to exert potential neuroprotective effects. However, the mechanisms remain unknown. To this end, we are prompted to investigate whether PGA1 is a useful neurological treatment for Alzheimer's disease (AD) or not. Using high-throughput sequencing, we found that PGA1 potentially regulates cholesterol metabolism and lipid transport. Interestingly, we further found that short-term administration of PGA1 decreased the levels of the monomeric and oligomeric β-amyloid protein (oAβ) in a cholesterol-dependent manner. In detail, PGA1 activated the peroxisome proliferator-activated receptor-gamma (PPARγ) and ATP-binding cassette subfamily A member 1 (ABCA1) signalling pathways, promoting the efflux of cholesterol and decreasing the intracellular cholesterol levels. Through PPARγ/ABCA1/cholesterol-dependent pathway, PGA1 decreased the expression of presenilin enhancer protein 2 (PEN-2), which is responsible for the production of Aβ. More importantly, long-term administration of PGA1 remarkably decreased the formation of Aβ monomers, oligomers, and fibrils. The actions of PGA1 on the production and deposition of Aβ ultimately improved the cognitive decline of the amyloid precursor protein/presenilin1 (APP/PS1) transgenic mice.

Gene-environment interactions in Alzheimer's disease: A potential path to precision medicine

Alzheimer's disease (AD) is the leading cause of dementia in the United States and afflicts >5.7 million Americans in 2018. Therapeutic options remain extremely limited to those that are symptom targeting, while no drugs have been approved for the modification or reversal of the disease itself. Risk factors for AD including aging, the female sex, as well as carrying an APOE4 genotype. These risk factors have been extensively examined in the literature, while less attention has been paid to modifiable risk factors, including lifestyle, and environmental risk factors such as exposures to air pollution and pesticides. This review highlights the most recent data on risk factors in AD and identifies gene by environment interactions that have been investigated. It also provides a suggested framework for a personalized therapeutic approach to AD, by combining genetic, environmental and lifestyle risk factors. Understanding modifiable risk factors and their interaction with non-modifiable factors (age, susceptibility alleles, and sex) is paramount for designing personalized therapeutic interventions.

CD55 upregulation in astrocytes by statins as potential therapy for AQP4-IgG seropositive neuromyelitis optica

Background

Neuromyelitis optica spectrum disorder (herein called NMO) is an inflammatory demyelinating disease that can be initiated by binding of immunoglobulin G autoantibodies (AQP4-IgG) to aquaporin-4 on astrocytes, causing complement-dependent cytotoxicity (CDC) and downstream inflammation. The increased NMO pathology in rodents deficient in complement regulator protein CD59 following passive transfer of AQP4-IgG has suggested the potential therapeutic utility of increasing the expression of complement regulator proteins.

Methods

A cell-based ELISA was developed to screen for pharmacological upregulators of endogenous CD55 and CD59 in a human astrocyte cell line. A statin identified from the screen was characterized in cell culture models and rodents for its action on complement regulator protein expression and its efficacy in models of seropositive NMO.

Results

Screening of ~ 11,500 approved and investigational drugs and nutraceuticals identified transcriptional upregulators of CD55 but not of CD59. Several statins, including atorvastatin, simvastatin, lovastatin, and fluvastatin, increased CD55 protein expression in astrocytes, including primary cultures, by three- to four-fold at 24 h, conferring significant protection against AQP4-IgG-induced CDC. Mechanistic studies revealed that CD55 upregulation involves inhibition of the geranylgeranyl transferase pathway rather than inhibition of cholesterol biosynthesis. Oral atorvastatin at 10–20 mg/kg/day for 3 days strongly increased CD55 immunofluorescence in mouse brain and spinal cord and reduced NMO pathology following intracerebral AQP4-IgG injection.

Conclusion

Atorvastatin or other statins may thus have therapeutic benefit in AQP4-IgG seropositive NMO by increasing CD55 expression, in addition to their previously described anti-inflammatory and immunomodulatory actions.

A combination of indomethacin and atorvastatin ameliorates cognitive and pathological deterioration in PrP-hAβPPswe/PS1ΔE9 transgenic mice

Mounting evidence has shown that inflammation might drive Alzheimer's disease (AD) pathology and contribute to its exacerbation. Previous studies have indicated that indomethacin or atorvastatin are beneficial in treating AD; however, no significant clinical effects have been shown. Furthermore, no study has investigated the efficacy of combining these agents for treating AD. This study sought to determine the effect of a combination of indomethacin and atorvastatin in the PrP-hAβPPswe/PS1^ΔE9 (APP/PS1) transgenic AD mouse model. Treatment with indomethacin and atorvastatin ameliorated impairments in spatial learning and memory, and the active avoidance response in APP/PS1 mice. Moreover, we found a suppression of Aβ plaques and decreased concentration of Aβ_1-42 in the hippocampus of APP/PS1 mice following treatment. In addition, indomethacin and atorvastatin ameliorated abnormal cytokine secretion, lymphocyte subset disorder, and hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axis imbalances in APP/PS1 mice. The combination of indomethacin and atorvastatin restored immune and neuroendocrine processes, attenuated pathologic changes and cognitive impairments in APP/PS1 transgenic mice, and could thus be a potential therapeutic agent for AD.

Statins and the Brain: More than Lipid Lowering Agents?

BACKGROUND

Statins represent a class of medications widely prescribed to efficiently treat dyslipidemia. These drugs inhibit 3-βhydroxy 3β-methylglutaryl Coenzyme A reductase (HMGR), the rate-limiting enzyme of mevalonate (MVA) pathway. Besides cholesterol, MVA pathway leads to the production of several other compounds, which are essential in the regulation of a plethora of biological activities, including in the central nervous system. For these reasons, statins are able to induce pleiotropic actions, and acquire increased interest as potential and novel modulators in brain processes, especially during pathological conditions.

OBJECTIVE

The purpose of this review is to summarize and examine the current knowledge about pharmacokinetic and pharmacodynamic properties of statins in the brain. In addition, effects of statin on brain diseases are discussed providing the most up-to-date information.

METHODS

Relevant scientific information was identified from PubMed database using the following keywords: statins and brain, central nervous system, neurological diseases, neurodegeneration, brain tumors, mood, stroke.

RESULTS

315 scientific articles were selected and analyzed for the writing of this review article. Several papers highlighted that statin treatment is effective in preventing or ameliorating the symptomatology of a number of brain pathologies. However, other studies failed to demonstrate a neuroprotective effect.

CONCLUSION

Even though considerable research studies suggest pivotal functional outcomes induced by statin therapy, additional investigation is required to better determine the pharmacological effectiveness of statins in the brain, and support their clinical use in the management of different neuropathologies.

Neuroprotective effects of statins against amyloid β-induced neurotoxicity

A growing body of evidence suggests that disruption of the homeostasis of lipid metabolism affects the pathogenesis of Alzheimer's disease (AD). In particular, dysregulation of cholesterol homeostasis in the brain has been reported to considerably increase the risk of developing AD. Thus, dysregulation of lipid homeostasis may increase the amyloid β (Aβ) levels by affecting amyloid precursor protein (APP) cleavage, which is the most important risk factor involved in the pathogenesis of AD. Previous research demonstrated that Aβ can trigger neuronal insulin resistance, which plays an important role in response to Aβ-induced neurotoxicity in AD. Epidemiological studies also suggested that statin use is associated with a decreased incidence of AD. Therefore, statins are believed to be a good candidate for conferring neuroprotective effects against AD. Statins may play a beneficial role in reducing Aβ-induced neurotoxicity. Their effect involves a putative mechanism beyond its cholesterol-lowering effects in preventing Aβ-induced neurotoxicity. However, the underlying molecular mechanisms of the protective effect of statins have not been clearly determined in Aβ-induced neurotoxicity. Given that statins may provide benefits beyond the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, these drugs may also improve the brain. Thus, statins may have beneficial effects on impaired insulin signaling by activating AMP-activated protein kinase (AMPK) in neuronal cells. They play a potential therapeutic role in targeting Aβ-mediated neurotoxicity.

Role of 4-hydroxy-2-nonenal (HNE) in the pathogenesis of alzheimer disease and other selected age-related neurodegenerative disorders

Oxidative stress is involved in various and numerous pathological states including several age-related neurodegenerative diseases. Peroxidation of the membrane lipid bilayer is one of the major sources of free radical-mediated injury that directly damages neurons causing increased membrane rigidity, decreased activity of membrane-bound enzymes, impairment of membrane receptors and altered membrane permeability and eventual cell death. Moreover, the peroxidation of polyunsaturated fatty acids leads to the formation of aldehydes, which can act as toxic by-products. One of the most abundant and cytotoxic lipid -derived aldehydes is 4-hydroxy 2-nonenal (HNE). HNE toxicity is mainly due to the alterations of cell functions by the formation of covalent adducts of HNE with proteins. A key marker of lipid peroxidation, HNE-protein adducts, were found to be elevated in brain tissues and body fluids of Alzheimer disease, Parkinson disease, Huntington disease and amyotrophic lateral sclerosis subjects and/or models of the respective age-related neurodegenerative diseases. Although only a few proteins were identified as common targets of HNE modification across all these listed disorders, a high overlap of these proteins occurs concerning the alteration of common pathways, such as glucose metabolism or mitochondrial function that are known to contribute to cognitive decline. Within this context, despite the different etiological and pathological mechanisms that lead to the onset of different neurodegenerative diseases, the formation of HNE-protein adducts might represent the shared leit-motif, which aggravates brain damage contributing to disease specific clinical presentation and decline in cognitive performance observed in each case.

Association of Cognitive Impairment in Patients on 3-Hydroxy-3-Methyl-Glutaryl-CoA Reductase Inhibitors

BACKGROUND

Atherosclerotic cardiovascular diseases are the leading cause of death in the United States. A reduction in cholesterol with 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (statin) significantly reduces mortality and morbidity. Statins may be associated with cognitive impairment or dementia. Our aim was to study the association of cognitive impairment or dementia in patients who were on a statin.

METHODS

Electronic medical records of 3,500 adult patients in our suburban internal medicine office were reviewed.

RESULTS

There were 720 (20.6%) patients in the statin treatment group. Dementia or cognitive impairment was an associated comorbid condition in 7.9% patients in the statin treatment group compared to 3.1% patients in the non-statin group (P < 0.001). Analysis of all of the patients with cognitive impairment or dementia showed that among the age ranges of 51 years through 100 years, the patients in the statin treatment group had a higher prevalence of cognitive impairment or dementia compared to the non-statin group. In the statin treatment group, we found significantly higher prevalence of hyperlipidemia (86.3%), hypertension (69.6%), diabetes mellitus (36.0%), osteoarthritis (31.5%), coronary artery disease (26.1%), hypothyroidism (21.5%) and depression (19.3%) compared to the non-statin group (P < 0.001). About 39.9% of the patients with dementia or cognitive impairment were on statin therapy compared to 18.9% patients who had no dementia or cognitive impairment and were on statin therapy (P < 0.001). Among the patients with cognitive deficit or dementia in the statin treatment group, the majority of the patients were either on atorvastatin (43.9%) or simvastatin (35.1%), followed by rosuvastatin (12.2%) and pravastatin (8.8%). We found greater odds of dementia or cognitive impairment with each year increase in age (1.3 times), in women (2.2 times), African American race (2.7 times), non-consumption of moderate amount of alcohol (two times), diabetes mellitus (1.6 times), hypothyroidism (1.7 times), cerebrovascular accident (3.2 times), and other rheumatological diseases (1.8 times).

CONCLUSIONS

The association of dementia or cognitive impairment was significantly higher in the patients who were on statin therapy compared to the patients who were not on a statin.

Simvastatin enhances the hippocampal klotho in a rat model of streptozotocin-induced cognitive decline

Brain oxidative status is a crucial factor in the development of sporadic Alzheimer's disease (AD). Klotho, an anti-aging protein, diminishes oxidative stress by the induction of manganese superoxide dismutase (MnSOD). Thus, the substances that increase klotho expression could be considered as a potential treatment for Alzheimer's disease when the oxidative imbalance is present. Statins are suggested to up-regulate klotho expression. We examined the effect of simvastatin (5mg/kg, daily for 3weeks) on hippocampal klotho and MnSOD expression in the cognitive declined animal model induced by intracerebroventricular (ICV)-streptozotocin (STZ) administration. Cognitive assessment was performed by the Morris Water Maze (MWM) test. The results indicated that mean escape latency and distance were prolonged in the ICV-STZ group compared with the control group. The expression of klotho and MnSOD were also down regulated in the hippocampus. Furthermore, improved spatial performance was observed in simvastatin-treated animals. This effect could be related to increase in oxidative stress tolerance as evidenced by klotho and MnSOD up-regulation. Our current study indicates that klotho upregulation may be a neuroprotective mechanism of simvastatin against cognitive decline in AD.

Atorvastatin enhances kainate-induced gamma oscillations in rat hippocampal slices

Atorvastatin has been shown to affect cognitive functions in rodents and humans. However, the underlying mechanism is not fully understood. Because hippocampal gamma oscillations (γ, 20-80 Hz) are associated with cognitive functions, we studied the effect of atorvastatin on persistent kainate-induced γ oscillation in the CA3 area of rat hippocampal slices. The involvement of NMDA receptors and multiple kinases was tested before and after administration of atorvastatin. Whole-cell current-clamp and voltage-clamp recordings were made from CA3 pyramidal neurons and interneurons before and after atorvastatin application. Atorvastatin increased γ power by ~ 50% in a concentration-dependent manner, without affecting dominant frequency. Whereas atorvastatin did not affect intrinsic properties of both pyramidal neurons and interneurons, it increased the firing frequency of interneurons but not that of pyramidal neurons. Furthermore, whereas atorvastatin did not affect synaptic current amplitude, it increased the frequency of spontaneous inhibitory post-synaptic currents, but did not affect the frequency of spontaneous excitatory post-synaptic currents. The atorvastatin-induced enhancement of γ oscillations was prevented by pretreatment with the PKA inhibitor H89, the ERK inhibitor U0126, or the PI3K inhibitor wortmanin, but not by the NMDA receptor antagonist D-AP5. Taken together, these results demonstrate that atorvastatin enhanced the kainate-induced γ oscillation by increasing interneuron excitability, with an involvement of multiple intracellular kinase pathways. Our study suggests that the classical cholesterol-lowering agent atorvastatin may improve cognitive functions compromised in disease, via the enhancement of hippocampal γ oscillations.

Atorvastatin ameliorates cognitive impairment, Aβ1-42 production and Tau hyperphosphorylation in APP/PS1 transgenic mice

Amyloid-beta (Aβ) interacts with the serine/threonine protein kinase AKT (also known as protein kinase B)/glycogen synthase kinase 3β (GSK3β) pathway and deactivates GSK3β signaling, which result in microtubule protein tau phosphorylation. Atorvastatin, a HMG-CoA reductase inhibitor, has been proven to improve learning and memory performance, reduce Aβ and phosphorylated tau levels in mouse model of Alzheimer's disease (AD). However, it still remains unclear whether atorvastatin is responsible for regulation of AKT/GSK3β signaling and contributes to subsequent down-regulation of Aβ1-42 and phosphorylated tau in APP/PS1 transgenic (Tg APP/PS1) mice. Herein, we aimed to investigate the possible impacts of atorvastatin (10 mg/kg, p.o.) on the memory deficit by behavioral tests and changes of AKT/GSK3β signaling in hippocampus and prefrontal cortex by western blot test in Tg APP/PS1 mice. The results showed that treatment with atorvastatin significantly reversed the memory deficit in the Tg APP/PS1 mice in a novel object recognition and the Morris water maze tests. Moreover, atorvastatin significantly attenuated Aβ1-42 accumulation and phosphorylation of tau (Ser396) in the hippocampus and prefrontal cortex of Tg APP/PS1 mice. In addition, atorvastatin treatment also increased phosphorylation of AKT, inhibited GSK3β activity by increasing phosphorylation of GSK3β (Ser9) and decreasing the beta-site APP cleaving enzyme 1 (BACE1) expression. These results indicated that the memory ameliorating effect of atorvastatin may be, in part, by regulation the AKT/GSK3β signaling which may contribute to down-regulation of Aβ1-42 and tau hyperphosphorylation.

Neurovascular and Cognitive failure in Alzheimer's Disease: Benefits of Cardiovascular Therapy

Alzheimer's disease (AD) is a multifactorial and multifaceted disease for which we currently have very little to offer since there is no curative therapy, with only limited disease-modifying drugs. Recent studies in AD mouse models that recapitulate the amyloid-β (Aβ) pathology converge to demonstrate that it is possible to salvage cerebrovascular function with a variety of drugs and, particularly, therapies used to treat cardiovascular diseases such as hypercholesterolemia and hypertension. These drugs can reestablish dilatory function mediated by various endothelial and smooth muscle ion channels as well as nitric oxide availability, benefits that result in normalized brain perfusion. These cerebrovascular benefits would favor brain perfusion, which may help maintain neuronal function and, possibly, delay cognitive failure. However, restoring cerebrovascular function in AD mouse models was not necessarily accompanied by rescue of cognitive deficits related to spatial learning and memory. The results with cardiovascular therapies rather suggest that drugs originally designed to treat cardiovascular diseases that concurrently restore cerebrovascular and cognitive function do so through their pleiotropic effects. Specifically, recent findings suggest that these drugs act directly on brain cells and neuronal pathways involved in memory formation, hence, working simultaneously albeit independently on neuronal and vascular targets. These findings may help select medications for patients with cardiovascular diseases at risk of developing AD with increasing age. Further, they may identify molecular targets for recovering memory pathways that bear potential for new therapeutic avenues.

Statin Therapy and the Development of Cerebral Amyloid Angiopathy--A Rodent in Vivo Approach

Background: Cerebral amyloid angiopathy (CAA) is characterized by vascular deposition of amyloid β (Aβ) with a higher incidence of cerebral microbleeds (cMBs) and spontaneous hemorrhage. Since statins are known for their benefit in vascular disease we tested for the effect on CAA. Methods: APP23-transgenic mice received atorvastatin-supplemented food starting at the age of eight months (n = 13), 12 months (n = 7), and 16 months (n = 6), respectively. Controls (n = 16) received standard food only. At 24 months of age cMBs were determined with T2*-weighted 9.4T magnetic resonance imaging and graded by size. Results: Control mice displayed an average of 35 ± 18.5 cMBs (mean ± standard deviation), compared to 29.3 ± 9.8 in mice with eight months (p = 0.49), 24.9 ± 21.3 with 12 months (p = 0.26), and 27.8 ± 15.4 with 16 months of atorvastatin treatment (p = 0.27). In combined analysis treated mice showed lower absolute numbers (27.4 ± 15.6, p = 0.16) compared to controls and also after adjustment for cMB size (p = 0.13). Conclusion: Despite to a non-significant trend towards fewer cMBs our results failed to provide evidence for beneficial effects of long-term atorvastatin treatment in the APP23-transgenic mouse model of CAA. A higher risk for bleeding complications was not observed.

The relationship between iron dyshomeostasis and amyloidogenesis in Alzheimer's disease: Two sides of the same coin

The dysregulation of iron metabolism in Alzheimer's disease is not accounted for in the current framework of the amyloid cascade hypothesis. Accumulating evidence suggests that impaired iron homeostasis is an early event in Alzheimer's disease progression. Iron dyshomeostasis leads to a loss of function in several enzymes requiring iron as a cofactor, the formation of toxic oxidative species, and the elevated production of beta-amyloid proteins. Several common genetic polymorphisms that cause increased iron levels and dyshomeostasis have been associated with Alzheimer's disease but the pathoetiology is not well understood. A full picture is necessary to explain how heterogeneous circumstances lead to iron loading and amyloid deposition. There is evidence to support a causative interplay between the concerted loss of iron homeostasis and amyloid plaque formation. We hypothesize that iron misregulation and beta-amyloid plaque pathology are synergistic in the process of neurodegeneration and ultimately cause a downward cascade of events that spiral into the manifestation of Alzheimer's disease. In this review, we amalgamate recent findings of brain iron metabolism in healthy versus Alzheimer's disease brains and consider unique mechanisms of iron transport in different brain cells as well as how disturbances in iron regulation lead to disease etiology and propagate Alzheimer's pathology.

Impact on cognitive function-are all statins the same?

Dementia is a major public health concern, affecting an estimated 7% of the population over 65 and 30% over 80 years of age. There is mounting evidence in the literature from meta-analyses of high-quality prospective cohort studies that statins may have a positive impact in reducing the incidence of dementia. Little is known, however, on whether certain types of statins are more impactful than others. This narrative review specifically explores the various properties of different statin types and whether these differences lead to a clinically significant differential impact on cognitive function. We critically evaluate the literature, emphasizing interesting and important new findings, and overall aim to bring the reader up-to-date on evidence-based recommendations.

Are microRNAs the Molecular Link Between Metabolic Syndrome and Alzheimer's Disease?

Alzheimer's disease (AD) is the most common cause of dementia in people over 65 years of age. At present, treatment options for AD address only its symptoms, and there are no available treatments for the prevention or delay of the disease process. Several preclinical and epidemiological studies have linked metabolic risk factors such as hypertension, obesity, dyslipidemia, and diabetes to the pathogenesis of AD. However, the molecular mechanisms that underlie this relationship are not fully understood. Considering that less than 1% of cases of AD are attributable to genetic factors, the identification of new molecular targets linking metabolic risk factors to neuropathological processes is necessary for improving the diagnosis and treatment of AD. The dysregulation of microRNAs (miRNAs), small non-coding RNAs that regulate several biological processes, has been implicated in the development of different pathologies. In this review, we summarize some of the relevant evidence that points to the role of miRNAs in metabolic syndrome (MetS) and AD and propose that miRNAs may be a molecular link in the complex relationship between both diseases.

Atorvastatin prevents Aβ oligomer-induced neurotoxicity in cultured rat hippocampal neurons by inhibiting Tau cleavage

AIM

The proteolytic cleavage of Tau is involved in Aβ-induced neuronal dysfunction and cell death. In this study, we investigated whether atorvastatin could prevent Tau cleavage and hence prevent Aβ1-42 oligomer (AβO)-induced neurotoxicity in cultured cortical neurons.

METHODS

Cultured rat hippocampal neurons were incubated in the presence of AβOs (1.25 μmol/L) with or without atorvastatin pretreatment. ATP content and LDH in the culture medium were measured to assess the neuronal viability. Caspase-3/7 and calpain protease activities were detected. The levels of phospho-Akt, phospho-Erk1/2, phospho-GSK3β, p35 and Tau proteins were measured using Western blotting.

RESULTS

Treatment of the neurons with AβO significantly decreased the neuronal viability, induced rapid activation of calpain and caspase-3/7 proteases, accompanied by Tau degradation and relatively stable fragments generated in the neurons. AβO also suppressed Akt and Erk1/2 kinase activity, while increased GSK3β and Cdk5 activity in the neurons. Pretreatment with atorvastatin (0.5, 1, 2.5 μmol/L) dose-dependently inhibited AβO-induced activation of calpain and caspase-3/7 proteases, and effectively diminished the generation of Tau fragments, attenuated synaptic damage and increased neuronal survival. Atorvastatin pretreatment also prevented AβO-induced decreases in Akt and Erk1/2 kinase activity and the increases in GSK3β and Cdk5 kinase activity.

CONCLUSION

Atorvastatin prevents AβO-induced neurotoxicity in cultured rat hippocampal neurons by inhibiting calpain- and caspase-mediated Tau cleavage.

SIRT1 in the brain-connections with aging-associated disorders and lifespan

The silent mating type information regulation 2 proteins (sirtuins) 1 of class III histone deacetylases (HDACs) have been associated with health span and longevity. SIRT1, the best studied member of the mammalian sirtuins, has a myriad of roles in multiple tissues and organs. However, a significant part of SIRT1's role that impinges on aging and lifespan may lie in its activities in the central nervous system (CNS) neurons. Systemically, SIRT1 influences energy metabolism and circadian rhythm through its activity in the hypothalamic nuclei. From a cell biological perspective, SIRT1 is a crucial component of multiple interconnected regulatory networks that modulate dendritic and axonal growth, as well as survival against stress. This neuronal cell autonomous activity of SIRT1 is also important for neuronal plasticity, cognitive functions, as well as protection against aging-associated neuronal degeneration and cognitive decline. We discuss recent findings that have shed light on the various activities of SIRT1 in the brain, which collectively impinge on aging-associated disorders and lifespan.

Molecular mechanisms underlying the effects of statins in the central nervous system

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, commonly referred to as statins, are widely used in the treatment of dyslipidaemia, in addition to providing primary and secondary prevention against cardiovascular disease and stroke. Statins’ effects on the central nervous system (CNS), particularly on cognition and neurological disorders such as stroke and multiple sclerosis, have received increasing attention in recent years, both within the scientific community and in the media. Current understanding of statins’ effects is limited by a lack of mechanism-based studies, as well as the assumption that all statins have the same pharmacological effect in the central nervous system. This review aims to provide an updated discussion on the molecular mechanisms contributing to statins’ possible effects on cognitive function, neurodegenerative disease, and various neurological disorders such as stroke, epilepsy, depression and CNS cancers. Additionally, the pharmacokinetic differences between statins and how these may result in statin-specific neurological effects are also discussed.

Suppression of memory acquisition following co-administration of lithium and atorvastatin through nitric oxide pathway in mice

PURPOSE

The aim of this study was to investigate the interactive effect of lithium and atorvastatin on cognitive performance and the role of NO as a potential mechanism involved in this interaction.

MATERIALS AND METHODS

Memory performance was evaluated in a two-trial recognition Y-maze test and a step-through passive avoidance task in mice. Lithium (5, 10, 20 or 40 mg/kg, i.p.) and atorvastatin (1 mg/kg, p.o.) were administered 1 h before each trial, L-NAME, a non-specific NO synthase inhibitor (3, 10 mg/kg, i.p.); aminoguanidine, a specific inducible NO synthase (iNOS) inhibitor (100 mg/kg); and L-arginine, a NO precursor (750 mg/kg) were administered 30 min before training sessions. The level of plasma NO end-products (NOx) was determined using Griess reagent protocol.

RESULTS

1) Lithium (40 mg/kg) impaired the acquisition of spatial recognition memory; 2) lithium did not affect the retrieval phase of spatial memory; 3) atorvastatin (1 mg/kg) significantly impaired the memory performance, when co-administered with the sub-effective dose of lithium (10 mg/kg), but did not affect the status when administered with lithium (5 mg/kg); 4) L-NAME (10 mg/kg) and aminoguanidine (100 mg/kg) dramatically decreased memory performance in mice received sub-effective doses of both lithium (5 mg/kg) and atorvastatin (1 mg/kg); 5) L-arginine (750 mg/kg) improved the memory acquisition in mice administered lithium (10 mg/kg) and atorvastatin (1 mg/kg); 6) lithium did not affect the cognitive performance in the passive avoidance test. All results were compatible and confirmed with in vitro determination of plasma NOx levels.

CONCLUSIONS

Lithium, dose dependently, impaired acquisition phase of spatial recognition memory. Lithium and atorvastatin co-administration impaired spatial recognition memory mediating by nitrergic pathway. In addition to L-arginine, our data from L-NAME and aminoguanidine also support the involvement of NO pathway in this interaction.

MicroRNA-208a increases myocardial fibrosis via endoglin in volume overloading heart

MicroRNA-208a (mir-208a) is essential for cardiac hypertrophy and fibrosis. Endoglin, a co-receptor of transforming growth factor-β is also essential for cardiac fibrosis. Endoglin has been shown to be a target of mir-208a in the in vitro mechanical stress model. Volume overload can lead to heart failure and cardiac fibrosis. The role of mir-208a and endoglin in volume overload heart failure is well known. We sought to investigate the mechanism of regulation of mir-208a and endoglin in volume overload-induced heart failure. Aorta-caval (AV) shunt was performed in adult Sprague-Dawley rats to induce volume overload. Heart weight and heart weight/body weight ratio significantly increased in AV shunt animals. AV shunt significantly increased left ventricular end-diastolic dimension as compared to sham group. Mir-208a was significantly induced by AV shunt from 3 to 14 days. Endoglin, myosin heavy chain-β and brain natriuretic peptide were significantly induced by AV shunt from 3 to 14 days. Overexpression of mir-208a in the sham group without AV shunt significantly increased endoglin expression similar to the AV shunt group. Antagomir-208a attenuated the endoglin expression induced by AV shunt. Pretreatment with atorvastatin also attenuated the endoglin expression induced by AV shunt. AV shunt significantly increased myocardial fibrosis as compared to sham group. Overexpression of mir-208a in the sham group significantly increased myocardial fibrosis. Antagomir-208a and atorvastatin significantly attenuated the myocardial fibrosis induced by AV shunt. In conclusion, mir-208a increased endoglin expression to induce myocardial fibrosis in volume overloaded heart failure. Treatment with atorvastatin can attenuate the myocardial fibrosis induced by volume overload through inhibition of endoglin expression.

Effects of HMG-CoA reductase inhibitors on learning and memory in the guinea pig

Statins reduce the risk of death from cardiovascular disease in millions of people worldwide. Recent pharmacovigilance data has suggested that people taking statins have an increased risk of psychiatric adverse events such as amnesia and anxiety. This study aimed to investigate the possibility of statin-induced amnesia through animal models of memory and learning. We conducted extracellular field recordings of synaptic transmission in area CA1 of hippocampal slices to examine the effects of acute cholesterol lowering with lipid lowering drugs. We also assessed the effect of six weeks of simvastatin (2mg/kg/d) and atorvastatin (1mg/kg/d) treatment using the Morris water maze. Long Term Potentiation (LTP) was significantly diminished in the presence of 3µM atorvastatin or simvastatin and by the cholesterol sequestering agent methyl-β-cyclodextrin (MBCD). The effects were reversed in the MBCD but not the statin treated slices by the addition of cholesterol. In the water maze, statin treatment did not cause any deficits in the first five days of reference memory testing, but statin treated guinea pigs preformed significantly worse than control animals in a working memory test. The deficits observed in our experiments in water maze performance and hippocampal LTP are suggestive of statin induced changes in hippocampal plasticity. The effects on LTP are independent of cholesterol regulation, and occur at concentrations that may be relevant to clinical use. Our results may help to explain some of the behavioural changes reported in some people after beginning statin treatment.

Eradication of Helicobacter pylori Is Associated with the Progression of Dementia: A Population-Based Study

Objective. To evaluate the effect of eradication of Helicobacter pylori (H. pylori) on the progression of dementia in Alzheimer's disease (AD) patients with peptic ulcer. Methods. Participants with the diagnosis of AD and peptic ulcer were recruited between 2001 and 2008. We examined the association between eradication of H. pylori and the progression of AD using the multiple regression models. Medication shift from Donepezil, Rivastgmine, and Galantamine to Mematine is defined as progression of dementia according to the insurance of National Health Insurance (NHI) under expert review. Results. Among the 30142 AD patients with peptic ulcers, the ratio of medication shift in AD patients with peptic ulcers is 79.95%. There were significant lower incidence comorbidities (diabetes mellitus, hypertension, cerebrovascular disease, coronary artery disease, congestive heart failure and hyperlipidemia) in patients with H. pylori eradication as compared with no H. pylori eradication. Eradication of H. pylori was associated with a decreased risk of AD progression (odds ratio [OR] 0.35 [0.23–0.52]) as compared with no H. pylori eradication, which was not modified by comorbidities. Conclusions. Eradication of H. pylori was associated with a decreased progression of dementia as compared to no eradication of H. pylori in AD patients with peptic ulcers.