Defensive effect of lansoprazole in dementia of AD type in mice exposed to streptozotocin and cholesterol enriched diet

Selection of lansoprazole from an FDA-approved drug library to inhibit the Alzheimer's disease seed-dependent formation of tau aggregates

The efficacy of current treatments is still insufficient for Alzheimer's disease (AD), the most common cause of Dementia. Out of the two pathological hallmarks of AD amyloid-β plaques and neurofibrillary tangles, comprising of tau protein, tau pathology strongly correlates with the symptoms of AD. Previously, screening for inhibitors of tau aggregation that target recombinant tau aggregates have been attempted. Since a recent cryo-EM analysis revealed distinct differences in the folding patterns of heparin-induced recombinant tau filaments and AD tau filaments, this study focused on AD seed-dependent tau aggregation in drug repositioning for AD. We screened 763 compounds from an FDA-approved drug library using an AD seed-induced tau aggregation in SH-SY5Y cell-based assay. In the first screening, 180 compounds were selected, 72 of which were excluded based on the results of lactate dehydrogenase assay. In the third screening with evaluations of soluble and insoluble tau, 38 compounds were selected. In the fourth screening with 3 different AD seeds, 4 compounds, lansoprazole, calcipotriene, desogestrel, and pentamidine isethionate, were selected. After AD seed-induced real-time quaking-induced conversion, lansoprazole was selected as the most suitable drug for repositioning. The intranasal administration of lansoprazole for 4 months to AD seed-injected mice improved locomotor activity and reduced both the amount of insoluble tau and the extent of phosphorylated tau-positive areas. Alanine replacement of the predicted binding site to an AD filament indicated the involvement of Q351, H362, and K369 in lansoprazole and C-shaped tau filaments. These results suggest the potential of lansoprazole as a candidate for drug repositioning to an inhibitor of tau aggregate formation in AD.

Association of Proton Pump Inhibitor Use With Incident Dementia and Cognitive Decline in Older Adults: A Prospective Cohort Study

BACKGROUND & AIMS

Prior studies have suggested that proton pump inhibitor (PPI) use is associated with increased risk of dementia; however, these have been limited by incomplete assessment of medication use and failure to account for confounders. Furthermore, prior studies have relied on claims-based diagnoses for dementia, which can lead to misclassification. We investigated the associations of PPI and histamine-2 receptor antagonist (H2RA) use with dementia and cognitive decline.

METHODS

We conducted a post hoc analysis of ASPirin in Reducing Events in the Elderly (ASPREE), a randomized trial of aspirin in the United States and Australia, including 18,934 community-based adults ≥65 years of all races/ethnicities. Baseline and recent PPI and H2RA use were determined according to review of medications during annual in-person study visits. Incident dementia was defined according to Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition, criteria. Secondary endpoints include cognitive impairment, no dementia (CIND) and changes in cognition. Associations of medication use with dementia and CIND outcomes were examined using Cox proportional hazards models. Changes in cognitive test scores were examined using linear mixed-effects models.

RESULTS

Baseline PPI use vs nonuse was not associated with incident dementia (multivariable hazard ratio, 0.88; 95% confidence interval, 0.72-1.08), CIND (multivariable hazard ratio, 1.00; 95% confidence interval, 0.92-1.09), or with changes in overall cognitive test scores over time (multivariable B, -0.002; standard error, 0.01; P = .85). Similarly, no associations were observed between H2RA use and all cognitive endpoints.

CONCLUSIONS

In adults ≥65 years of age, PPI and H2RA use were not associated with incident dementia, CIND, or decline in cognition over time. These data provide reassurance about the safety of long-term use of PPIs among older adults.

Animal model of Alzheimer's disease induced by streptozotocin: New insights about cholinergic pathway

Alzheimer's disease (AD) is of multifactorial origin, and still presents several gaps regarding its development and progression. Disorders of the cholinergic system are well known to be involved in the pathogenesis of AD, characterized by increased acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and decreased acetyltransferase (ChAT) enzymatic activities. Late onset AD (LOAD) animal model induced by intracerebroventricular injection of streptozotocin (icv-STZ) showed promising results in this context, due to the similarity with the pathophysiology of human LOAD. Thus, this study aimed to assess the long-term effects of icv-STZ on the cholinergic system, through the measuring of AChE and BChE enzymatic activities in hippocampus, prefrontal cortex and liver of animals euthanized 30 and 120-days after the icv-STZ. Regarding the cholinergic response to icv-STZ, the 30-days and 120-days STZ-induced rats exhibit decreased AChE and BChE activities only in the hippocampus. The cognitive deficit was more consistent in the 30-days post icv-STZ animals, as was the weight loss. This is the first study to investigate the long-term effects (more than 60 days) of the icv-STZ on AChE and BChE activities, and our results, as well as those of a recent study, suggest that the cholinergic system may not be compromised by icv-STZ, at least in the long term, which means that this model may not be the best model for studying the cholinergic system in AD or that it is informative only for a short period.

Bergenin ameliorates cognitive deficits and neuropathological alterations in sodium azide-induced experimental dementia

Background: Bergenin, 4-O-methyl gallic acid glucoside, is a bioactive compound found in the cortex of Mallotus japonicus (L.f.) Müll.Arg. along with many other natural resources including that from Bergenia species. The present study delineates the neuroprotective potential of bergenin through the modulation of PPAR-γ receptors.

Method: Dementia was induced in the Wistar rats by intraperitoneal (i.p.) administration of sodium azide (12.5 mg/kg for the first 5 days followed by 10 mg/kg for the next 9 days). The rats were then exposed to the Morris water maze test to assess the effect on cognitive abilities followed by a series of biochemical and histopathological evaluations.

Results: Sodium azide-treated rats exhibited a severe deterioration of memory as suggested by poor performance in the spatial learning task in addition to the enhancement of brain acetylcholinesterase potential, oxidative stress, inflammation, and amyloid-β (Aβ) accumulation. Administration of bergenin to sodium azide-treated rats significantly recovered cognition and related biochemical variations. Further, co-administration of Bisphenol A diglycidyl ether (BADGE), a PPAR-γ antagonist with bergenin challenged its neuroprotective effects.

Conclusions: The findings of our study exhibit that the cognitive restoration potential of bergenin may be attributed to its modulatory effects against cholinesterase, oxidative stress, and inflammatory markers, as well as its neuroprotective actions, thus aligning it as a possible therapy for Alzheimer’s disease-related dementia. The study also fortifies the significance of PPAR-γ receptors in dementia.

Quercetin Exhibits α7nAChR/Nrf2/HO-1-Mediated Neuroprotection Against STZ-Induced Mitochondrial Toxicity and Cognitive Impairments in Experimental Rodents

The objective of the present study was to investigate the α7nAChR-mediated Nrf2-dependant protective activity against streptozotocin (STZ)-induced brain mitochondrial toxicity in Alzheimer's disease (AD)-like rats. STZ (3 mg/kg) was injected through an intracerebroventricular route to induce AD-like dementia. Repeated Quercetin (50 mg/kg, i.p.) administration attenuated cognitive impairments in the STZ-challenged animals during Morris water-maze and Y-maze tests. Quercetin significantly mitigated the STZ-induced increase in cholinergic dysfunction, such as the increase in acetylcholinesterase activity, decrease in acetylcholine level, and activity of choline acetyltransferase, and increase in amyloid-beta aggregation and mitochondrial toxicity in respect of mitochondrial bioenergetics, integrity, and oxidative stress in memory-challenged rat hippocampus, prefrontal cortex and, amygdala. Further, Quercetin significantly attenuated STZ-induced reduction in the α7nAChRs and HO-1 expression levels in the selected rat brain regions. On the contrary, trigonelline (10 mg/kg, i.p.) and methyllycaconitine (2 mg/kg; i.p.) abolished the neuroprotective effects of Quercetin against STZ-induced behavioral, molecular, and biochemical alterations in the AD-like animals. Hence, Quercetin exhibits α7nAChR/Nrf2/HO-1-mediated neuroprotection against STZ-challenged AD-like animals. Thus, Quercetin could be considered as a potential therapeutic option in the management of AD.

No association between acid suppressant use and risk of dementia: an updated meta-analysis

PURPOSE

Findings from large observational studies on whether the use of acid suppressants increases the risk of dementia have been inconsistent. Since proton pump inhibitors (PPI) and histamine-2 receptor antagonists (H2RA) are the most commonly used acid suppressants in clinical practice, we performed a meta-analysis to examine the influence of PPI and H2RA on the risk of dementia.

METHODS

A systematic search was performed on the PubMed, EMBASE, and Cochrane Library databases to identify studies published up to April, 2021. Studies that reported adjusted hazard ratio (HR) with 95% confidence intervals (CI) for the associations of interest were included. Data in the included studies were pooled using the random-effects model for meta-analysis. Statistical analysis was performed using Stata version 12.0 software.

RESULTS

Seventeen studies involving 1,251,562 participants were included. It was found that PPI users were not likely to develop dementia compared with those not taking PPI (HR = 0.98, 95% CI: 0.85-1.13). Subgroup analysis based on publication year, location, mean age, duration of PPI use, and female proportion also revealed no association between PPI use and dementia risk. Similarly, H2RA use was not associated with the risk of dementia, as indicated by the pooled HR of 1.20 (95% CI: 0.98-1.47).

CONCLUSION

Results of this meta-analysis suggest that PPI and H2RA do not increase the risk of dementia. These results may be used to inform the clinical application of acid suppressants. However, further randomized controlled trials are needed to confirm the present conclusions.

The effects of proton pump inhibitors on neuropsychological functioning

OBJECTIVE

The current study investigated the effects of proton pump inhibitor use and apolipoprotein ε4 carrier status on changes in neuropsychological functioning in healthy adults with familial risk factors for dementia.

METHODS

As part of the Wisconsin Registry for Alzheimer's Prevention study, 1,573 subjects were administered questionnaires on their medical history, gave blood samples, and were administered neuropsychological assessments during four visits over a 10-15 year period. Linear mixed models assessed if non-users, subjects who stopped, started, or consistently used proton pump inhibitors differed in changes in working memory, verbal memory, psychomotor speed, and cognitive flexibility.

RESULTS

The models did not yield significant main effects for proton pump inhibitor use or interaction effects between proton pump inhibitor use and apolipoprotein ε4 carrier status on a decline in memory or processing speed. An interaction effect suggested stopping a proton pump inhibitor may be protective against declines in cognitive flexibility among non-carriers.

CONCLUSIONS

Although stopping a proton pump inhibitor use may have mild protective effects on executive functioning for non-apolipoprotein ε4 carriers, proton pump inhibitor use was not associated with memory decline in a sample of subjects with familial risk factors for dementia.

Favorable effects of dill tablets and Ocimum basilicum L. extract on learning, memory, and hippocampal fatty acid composition in hypercholesterolemic rats

OBJECTIVES

Hypercholesterolemia is correlated with brain amyloid-β (Aβ) deposition and impaired cognitive functions and contributes to Alzheimer's disease. Effects of cholesterol-lowering dill tablets and aqueous extract of Ocimum basilicum L. (basil) on learning and memory and hippocampus fatty acid composition were examined. mRNA levels of the genes involved in cholesterol homeostasis were also determined in high-cholesterol diet (HCD) fed rats.

MATERIALS AND METHODS

Forty male Wistar rats were allocated to 4 groups: rats fed chow diet (C); rats fed high-cholesterol (2%) diet (HCD); rats treated with HCD+300 mg/kg dill tablets (HCD+Dill); and finally, rats fed HCD and treated with 400 mg/kg basil aqueous extract (HCD+basil). Treatment was carried out for 16 weeks. Hippocampus Aβ(1-42) level was determined. Spatial and passive avoidance tests were used to examine cognitive functions. Hippocampal FA composition was assessed by gas chromatography. Basil aqueous extract was analyzed by GC-double mass spectroscopy (GC-MS/MS) and expression of LXR-α, LXR-β, and ABCA1 genes was assessed by qRT-PCR.

RESULTS

Dill tablets and basil extract remarkably ameliorated serum cholesterol (P<0.001), retarded hippocampal accumulation of Aβ, and attenuated HCD-induced memory impairment. Hippocampus FA composition did not change but serum cholesterol was found positively correlated with hippocampus Aβ(1-42) (P<0.001), total n 6 PUFA (P=0.013), and Aβ(1-42) showed correlation with the ratio of n6 to n3 PUFA. At least 70 components were identified in basil aqueous extract.

CONCLUSION

Dill tablets and aqueous extract of basil attenuated the hypercholesterolemia-induced memory impairment by lowering serum cholesterol and hippocampus amyloid deposits, and probably beneficial in AD adjuvant therapy.

Proton pump inhibitors and dementia risk: Evidence from a cohort study using linked routinely collected national health data in Wales, UK

OBJECTIVES

Proton pump inhibitors (PPIs) are commonly prescribed for prevention and treatment of gastrointestinal conditions or for gastroprotection from other drugs. Research suggests they are linked to increased dementia risk. We use linked national health data to examine the association between PPI use and the development of incident dementia.

METHODS AND FINDINGS

A population-based study using electronic health-data from the Secure Anonymised Information Linkage (SAIL) Databank, Wales (UK) from 1999 to 2015. Of data available on 3,765,744 individuals, a cohort who had ever been prescribed a PPI was developed (n = 183,968) for people aged 55 years and over and compared to non-PPI exposed individuals (131,110). Those with prior dementia, mild-cognitive-impairment or delirium codes were excluded. Confounding factors included comorbidities and/or drugs associated with them. Comorbidities might include head injury and some examples of medications include antidepressants, antiplatelets and anticoagulants. These commonly prescribed drugs were investigated as it was not feasible to explore all drugs in this study. The main outcome was a diagnosis of incident dementia. Cox proportional hazard regression modelling was used to calculate the Hazard ratio (HR) of developing dementia in PPI-exposed compared to unexposed individuals while controlling for potential confounders. The mean age of the PPI exposed individuals was 69.9 years and 39.8% male while the mean age of the unexposed individuals was 72.1 years and 41.1% male. The rate of PPI usage was 58.4% (183,968) and incident dementia rate was 11.8% (37,148/315,078). PPI use was associated with decreased dementia risk (HR: 0.67, 95% CI: 0.65 to 0.67, p<0.01).

CONCLUSIONS

This study, using large-scale, multi-centre health-data was unable to confirm an association between PPI use and increased dementia risk. Previously reported links may be associated with confounders of people using PPI's, such as increased risk of cardiovascular disease and/or depression and their associated medications which may be responsible for any increased risk of developing dementia.

Neuroprotective role of alendronate against APP processing and neuroinflammation in mice fed a high fat diet

Obesity and consumption of diet rich in fat are known to contribute to the development of Alzheimer's disease (AD) which is a complex and multifactorial neurodegenerative disease and a leading cause of mortality with unmet medical needs. Hypercholesterolemia was discovered to increase neuropathological changes along with cognitive decline in AD mouse models but still the underlying mechanism is elusive. Furthermore, isoprenoids, the crucial products of Mevalonate-pathway produced by the action of farnesyl pyrophosphate synthase (FPPS) enzyme, are also demonstrated to play a key role in AD. Nevertheless, bisphosphonates target this enzyme in order to treat osteoporosis and also found to alleviate dementia in such patients. As per the cited inhibitory action of alendronate, against acetylcholinesterase and cholesterol level, we hypothesized to explore the potential of alendronate against high fat diet (HFD) induced neuropathologies and cognitive disabilities in AD mouse model. Here we noticed that in mice provided with HFD for 14 weeks, spatial memory was compromised as interpreted in different behavioral paradigms. Together with cognitive depletion, there was observed a provoking effect on amyloid precursor protein (APP)-processing via amyloidogenic pathway due to enhanced β-site APP cleaving enzyme-1 (BACE-1) level which in turn leads to augmented release of amyloid beta (Aβ) in hippocampus of HFD mice. Relevant to these, significant elevation in hippocampal level of neuroinflammatory cytokines, oxidative stress markers and isoprenoids and serum cholesterol were also found after HFD exposure. Marked reversal of cognitive impairment, enhanced APP-processing, neuroinflammation along with other neuropathological alterations in hippocampus was demonstrated following oral administration of alendronate (1.76 mg/kg) for 15 days despite of HFD treatment. These changes were noted to be due to modulation of isoprenoids and cholesterol level by alendronate. Supporting these, histopathological analysis done by congo red revealed the reduced Aβ deposition in hippocampus of drug treated HFD mice The current outcomes provide important implications for the contribution of Mevalonate-pathway and HFD for the onset of AD and also support alendronate as a prominent intervention for amelioration of AD-like pathologies.

Effects of metformin on recognition memory and hippocampal neuroplasticity in rats with metabolic syndrome

Metabolic syndrome (MS) is a health problem that is characterized by body fat accumulation, hypertension, dyslipidemia, and hyperglycemia; recently, it has been demonstrated that MS also damages memory processes. The first-line drug in the treatment of MS and type 2 diabetes mellitus is metformin, which is an antihyperglycemic agent. This drug has been shown to produce neuroprotection and to improve memory processes. However, the mechanism involved in this neuroprotection is unknown. A 90-day administration of metformin improved the cognitive processes of rats with MS as evaluated by the novel object recognition test, and this finding could be explained by an increase in the neuronal spine density and spine length. We also found that metformin increased the immunoreactivity of synaptophysin, sirtuin-1, AMP-activated protein kinase, and brain-derived neuronal factor, which are important plasticity markers. We conclude that metformin is an important therapeutic agent that increases neural plasticity and protects cognitive processes. The use of this drug is important in the minimization of the damage caused by MS.

Xanthotoxin and umbelliferone attenuate cognitive dysfunction in a streptozotocin-induced rat model of sporadic Alzheimer's disease: The role of JAK2/STAT3 and Nrf2/HO-1 signalling pathway modulation

The aim of the present study was to assess the neuroprotective effects of xanthotoxin and umbelliferone in streptozotocin (STZ)-induced cognitive dysfunction in rats. Animals were injected intracerebroventricularly (ICV) with STZ (3 mg/kg) once to induce a sporadic Alzheimer's disease (SAD)-like condition. Xanthotoxin or umbelliferone (15 mg/kg, i.p.) were administered 5 hr after ICV-STZ and daily for 20 consecutive days. Xanthotoxin or umbelliferone prevented cognitive deficits in the Morris water maze and object recognition tests. In parallel, xanthotoxin or umbelliferone reduced hippocampal acetylcholinestrase activity and malondialdehyde level. Moreover, xanthotoxin or umbelliferone increased glutathione content. These coumarins also modulated neuronal cell death by reducing the level of proinflammatory cytokines (tumour necrosis factor-alpha and interleukin-6), inhibiting the overexpression of inflammatory markers (nuclear factor κB [NF-κB] and cyclooxygenase II), and upregulating the expression of NF-κB inhibitor (IκB-α). Interestingly, xanthotoxin diminished phosphorylated JAK2 and phosphorylated STAT3 protein expression, while umbelliferone markedly replenished nuclear factor erythroid-derived 2-like 2 (Nrf2) and haem oxygenase-1 (HO-1) levels. The current study provides evidence for the protective effect of xanthotoxin and umbelliferone in STZ-induced cognitive dysfunction in rats. This effect may be attributed, at least in part, to inhibiting acetylcholinestrase and attenuating oxidative stress, neuroinflammation and neuronal loss.

No association between proton pump inhibitor use and risk of dementia: Evidence from a meta-analysis

BACKGROUND AND AIM

A growing body of literature suggests the association between dementia risk and proton pump inhibitor (PPI) use. Therefore, we aimed to investigate the association between PPI use and dementia risk.

METHODS

An extensive literature search was performed in PubMed, Embase, and Cochrane till March 31, 2019. All the studies (cohort and case-control) assessing the association between PPI use and dementia risk were eligible for inclusion. Articles were selected based on the screening of title and abstract, data were extracted, and risk of bias was assessed using Newcastle-Ottawa scale. The primary outcome was pooled risk of dementia among PPI user as compared with non-PPI user. Secondary outcomes include dementia risk based on subgroups. Statistical analysis was performed using review manager software.

RESULTS

Twelve studies (eight cohort and four case-control) were found to be eligible for inclusion. Majority of the studies were of high quality. Dementia was diagnosed based on International Classification of Diseases 9/10 codes in majority of the included studies. PPI use was not associated with the dementia risk, with a pooled relative risk (RR) of 1.05 (95% confidence interval [CI]: 0.96-1.15), P = 0.31. Subgroup analysis based on study design (cohort: P = 0.14; case-control: P = 0.14), sex (RR 1.25 [95% CI: 0.97-1.60], P = 0.08), histamine 2 receptor antagonist blockers (P = 0.93), and Alzheimer's disease (RR 1.00 [95% CI: 0.91-1.09], P = 0.93) revealed no significant association between PPI use and dementia risk.

CONCLUSION

We found no significant association between PPI use and the risk of dementia or Alzheimer's disease.

Time-course study of high fat diet induced alterations in spatial memory, hippocampal JNK, P38, ERK and Akt activity

Consumption of high fat diet (HFD) is a health concern in modern societies, which participate in wide range of diseases. One underlying mechanism in the HFD mediated pathologies is disruption of insulin signaling activity. It is believed that HFD activates several stress signaling molecules such as MAPKs signaling pathway and these molecules participate in harmful effects in different cell populations including hippocampal cells. However, the activity of MAPKs signaling molecules are time dependent, even causing some opposing effects. Given that, MAPKs activity fluctuate with time of stress, there is less cleared how different lengths of HFD consumption can affect hippocampal MAPK. To test how duration of HFD consumption affect hippocampal MAPKs and insulin signaling activity and animal's cognitive function, rats were fed with HFD for different lengths (up to 6 months) and after each point spatial memory performances of animals was tested, then the peripheral indices of insulin resistance and hippocampal MAPKs and insulin signaling activity was evaluated. Results showed that while different time courses of HFD, up to 6 months, did not bring about significant spatial memory impairment, meanwhile the peripheral insulin sensitivity as well as hippocampal insulin and MAPKs signaling showed significant fluctuations during the different time courses of high fat diet regime. These results showed that neuronal responses to HFD is not constant and differ in a time-dependent manner, it seems that in acute phase molecular responses aimed to compensate the HFD stress but in chronic states these responses failed and devastating effects of stress began.

Lack of Association Between Proton Pump Inhibitor Use and Cognitive Decline

BACKGROUND & AIMS

Studies of association between use of proton pump inhibitors (PPI) and dementia have yielded conflicting results. We investigated the effects of PPIs on cognitive decline in a study of middle-aged and elderly twins in Denmark.

METHODS

In a prospective study, we collected data from surveys of middle-aged individuals (46-67 years old; the Middle Aged Danish Twin study) and older individuals (the Longitudinal Study of Aging Danish Twins) who underwent cognitive assessments (a 5-component test battery) over a 10-year period (middle-age study, n = 2346) or a 2-year period (longitudinal study of aging: n = 2475). We determined cumulative use of PPIs 2 years prior study enrollment and during follow up, in defined daily doses (DDDs) of PPIs, using data from a nationwide prescription register. Multi-variable linear regression models were used to examine associations between cumulative PPI use and a composite score of cognitive function at baseline and decreases in scores during the follow-up periods.

RESULTS

Use of PPIs before study enrollment was associated with a slightly lower mean cognitive score at baseline in the middle age study. The adjusted difference in mean score of individuals with high consumption of PPIs (≥400 DDD) was lower than that of non-users in the middle-age study (mean crude score for high PPI use, 43.4 ± 13.1 vs for non-use, 46.8 ± 10.2; adjusted difference of 0.69 points; 95% CI, -4.98 to 3.61). In the longitudinal study of aging twins, individuals with high consumption of PPI had higher adjusted scores than non-users (mean crude score for high PPI use, 35.2 ± 10.8 vs for non-use, 36.2 ± 11.1; adjusted difference of 0.95 points; 95% CI, -1.88 to 3.79). In analyses of cognitive decline, among individuals with high consumption of PPIs in the longitudinal study of aging, the adjusted mean difference between baseline score and follow-up score was lower than that of non-users (mean crude score for high PPI use at baseline, 36.6 ± 10.1 and at follow up, 34.3 ± 12.3 vs for non-use at baseline, 38.1 ± 10.5 and at follow up, 37.6 ± 11.3; adjusted difference of -1.22 points; 95% CI, -3.73 to 1.29). In the middle-age study, users with the highest consumption of PPIs (≥1600 DDD) had slightly less cognitive decline than non-users (baseline mean crude score for high PPI use, 43.4 ± 10.1 and follow-up mean crude score, 41.3 ± 9.7 vs baseline score of 49.1 ± 10.2 for non-users and follow-up score of 46.3 ± 9.9 for non-users; adjusted difference of 0.94 points; 95% CI, -1.63 to 3.50). No stated differences in scores between PPI users and non-users were significant.

CONCLUSIONS

In analyzing data from 2 large population-based studies of twins in Denmark, we found no association between PPI use and cognitive decline.

Proton Pump Inhibitor Use and Dementia Risk: Prospective Population-Based Study

OBJECTIVES

To determine whether higher cumulative proton pump inhibitor (PPI) exposure is associated with greater dementia risk.

DESIGN

Prospective population-based cohort study.

SETTING

Kaiser Permanente Washington, an integrated healthcare delivery system in Seattle, Washington.

PARTICIPANTS

Individuals aged 65 and older without dementia at study entry (N = 3,484).

MEASUREMENTS

Participants were screened for dementia every 2 years, and those who screened positive underwent extensive evaluation. Dementia outcomes were determined using standard diagnostic criteria. Time-varying PPI exposure was determined from computerized pharmacy data and consisted of total standardized daily doses (TSDDs) dispensed to an individual in the prior 10 years. We also assessed duration of use. Multivariable Cox regression was used to estimate the association between PPI exposure and time to dementia or Alzheimer's disease (AD).

RESULTS

Over a mean follow-up of 7.5 years, 827 participants (23.7%) developed dementia (670 with possible or probable AD). PPI exposure was not associated with risk of dementia (P = .66) or AD (P = .77). For dementia, the risk for specific levels of cumulative exposure compared to no use was: 365 TSDDs (HR 0.87, 95% CI 0.65-1.18), 1,095 TSDDs (HR 0.99, CI 0.75-1.30) and 1,825 TSDDs (HR 1.13, CI 0.82-1.56). These TSDD levels represent approximately 1, 3 and 5 years of daily use respectively. Duration of PPI use was not associated with dementia outcomes either.

CONCLUSION

Proton pump inhibitor use was not associated with dementia risk, even for people with high cumulative exposure. Although there are other safety concerns with long-term PPI use, results from our study do not support that these medications should be avoided out of concern about dementia risk.

Streptozotocin Induces Mild Cognitive Impairment at Appropriate Doses in Mice as Determined by Long-Term Potentiation and the Morris Water Maze

Alzheimer's disease (AD) is a progressive neurodegenerative disease, and effective therapeutic drugs in the clinic are still lacking. Ideally, AD progression could be stopped at an early stage, such as at the mild cognitive impairment (MCI) stage. MCI refers to the clinical condition between normal aging and dementia. Patients with MCI experience memory loss but do not meet the criteria for the diagnosis of clinically probable AD. However, few MCI animal models have been established. Here, we used in vivo long-term potentiation (LTP) recording and the Morris water maze (MWM) to evaluate the effects of intracerebroventricular injection of streptozotocin (ICV-STZ) in mice. We found a relationship between cognitive behavior and LTP in vivo and determined the appropriate doses of STZ for a putative MCI animal model. Animals that received≥150μg of STZ exhibited cognitive impairment in the MWM test, and few changes in behavior tests were observed in animals receiving less than 150μg of STZ. In vivo LTP recordings revealed that the induction of LTP decreased significantly in STZ-treated animals, even at the lowest dose (25μg/mouse), in a dose-dependent manner. Pathology analysis revealed STZ-induced neuron loss in a dose-dependent manner, both in the cortex and in the hippocampus, as evidenced by a significantly decreased neuronal number in the cohort treated with 75μg of STZ/mouse. Our study indicated that a low dose (25μg/mouse) of STZ impaired neural plasticity; at a higher dose of 75μg/mouse STZ, further LTP deficits were noted along with induced neuronal loss in both the cortex and the hippocampus, which could be considered a possible MCI or pre-MCI animal model; and finally, at 150μg/mouse STZ, dementia was induced, feasibly indicating a state of AD.

Global loss of acetylcholinesterase activity with mitochondrial complexes inhibition and inflammation in brain of hypercholesterolemic mice

There exists an intricate relationship between hypercholesterolemia (elevated plasma cholesterol) and brain functions. The present study aims to understand the impact of hypercholesterolemia on pathological consequences in mouse brain. A chronic mouse model of hypercholesterolemia was induced by giving high-cholesterol diet for 12 weeks. The hypercholesterolemic mice developed cognitive impairment as evident from object recognition memory test. Cholesterol accumulation was observed in four discrete brain regions, such as cortex, striatum, hippocampus and substantia nigra along with significantly damaged blood-brain barrier by hypercholesterolemia. The crucial finding is the loss of acetylcholinesterase activity with mitochondrial dysfunction globally in the brain of hypercholesterolemic mice, which is related to the levels of cholesterol. Moreover, the levels of hydroxyl radical were elevated in the regions of brain where the activity of mitochondrial complexes was found to be reduced. Intriguingly, elevations of inflammatory stress markers in the cholesterol-rich brain regions were observed. As cognitive impairment, diminished brain acetylcholinesterase activity, mitochondrial dysfunctions, and inflammation are the prima facie pathologies of neurodegenerative diseases, the findings impose hypercholesterolemia as potential risk factor towards brain dysfunction.

Association Between Proton Pump Inhibitor Use and Cognitive Function in Women

BACKGROUND & AIMS

Studies have reported associations between proton pump inhibitor (PPI) use and dementia. However, data are lacking on long-term PPI use and cognitive function. We therefore examined associations between PPI use and performance in tests of cognitive function. Because of shared clinical indications, we examined associations for H2 receptor antagonists (H2RAs) as a secondary aim.

METHODS

We used prospectively collected data on medication use and other potential risk factors from 13,864 participants in the Nurses' Health Study II who had completed a self-administered computerized neuropsychological test battery. Multivariable linear regression models were used to examine associations between medication use and composite scores of psychomotor speed and attention, learning and working memory, and overall cognition.

RESULTS

We observed a modest association between duration of PPI use and scores for psychomotor speed and attention (mean score difference for PPI use of 9-14 years vs never users, -0.06; 95% confidence interval, -0.11 to 0.00; P_trend = .03). After controlling for H2RA use, the magnitude of this score difference was attenuated. Among individuals who did not use PPIs regularly, duration of H2RA use was associated with poorer cognitive scores, with the strongest association apparent for learning and working memory (mean score difference for H2RA users of 9-14 years vs never users, -0.20; 95% confidence interval, -0.32 to -0.08; P_trend < .001).

CONCLUSIONS

In an analysis of data from the Nurses' Health Study II, we did not observe a convincing association between PPI use and cognitive function. Our data do not support the suggestion that PPI use increases dementia risk. Because our primary hypothesis related to PPI use, our findings for H2RAs should be interpreted with caution.

Gold nanoparticles prevent cognitive deficits, oxidative stress and inflammation in a rat model of sporadic dementia of Alzheimer's type

Alzheimer's disease (AD) is the most common form of neurodegenerative dementia in the aged brain. Even though its etiology is unknown, factors such as neuroinflammation, mitochondrial dysfunction, formation of reactive oxygen species (ROS), and impaired insulin signaling may play a role. We used a sporadic AD model in rats generated by intracerebroventricular-streptozotocin (i.c.v.-STZ) injection to test the therapeutic effect of gold nanoparticles (GNPs). We tested the null hypothesis that there would be no difference between the STZ+GNPs group and the STZ group in the analyzed markers. We observed that STZ-induced impairment in mitochondrial ATP production, neuroinflammation, and oxidative stress were all prevented by GNP treatment. Moreover, while STZ induced deficits in both spatial and recognition memory, GNPs prevented this effect. These results suggest that GNPs may be considered as a potential treatment for dementias.

Protective effect of valproic acid in streptozotocin-induced sporadic Alzheimer's disease mouse model: possible involvement of the cholinergic system

Sporadic Alzheimer's disease (SAD) is a slowly progressive neurological disorder that is the most common form of dementia. Cholinergic system dysfunction and amyloid beta formation are the two main underlying pathological mechanisms for the disease development. In recent studies, insulin receptor desensitization and disturbances in the downstream effects of insulin receptor signaling were observed in the brains of Alzheimer's patients. Currently, intracereberoventricular (ICV) injection of streptozotocin (STZ) is found to induce behavioral, neurochemical, and structural alterations in animals resembling those found in SAD patients. Valproic acid (VPA), a histone deacetylase inhibitor (HDACi), was recently shown to regulate the transcription of several genes in both in vivo and in vitro models of Alzheimer's disease. The aim of the current study is to investigate the potential effect of different doses of valproic acid, in an ICV-STZ-induced animal model of SAD. Streptozotocin-injected mice showed cognitive and spatial memory dysfunction in the Y-maze, object recognition test, and Morris water maze (MWM) neurobehavioral tests. The mice also exhibited a decrease in acetylcholine (ACh) and neprilysin (NEP) levels accompanied by an increase in acetylcholinesterase (AChE) activity. For the first time to our knowledge, our findings have shown that VPA is capable of restoring ACh levels in ICV-STZ-injected mice, as well as normalizing both NEP levels and AChE activity. Via this mechanism, an enhancement of cognitive functions is observed. Thus, VPA is suggested to be a promising therapeutic approach against SAD.

Neuroprotective effects of metformin against Aβ-mediated inhibition of long-term potentiation in rats fed a high-fat diet

Metformin (Met) is used to treat neurodegenerative disorders such as Alzheimer's disease (AD). Conversely, high-fat diets (HFD) have been shown to increase AD risk. In this study, we investigated the neuroprotective effects of Met on β-amyloid (Aβ)-induced impairments in hippocampal synaptic plasticity in AD model rats that were fed a HFD. In this study, 32 adult male Wistar rats were randomly assigned to four groups: group I (control group, regular diet); group II (HFD+vehicle); group III (HFD+Aβ); or group IV (Met+HFD+Aβ). Rats fed a HFD were injected with Aβ to induce AD, allowed to recover, and treated with Met for 8 weeks. The rats were then anesthetized with intraperitoneal injections of urethane and placed in a stereotaxic apparatus for surgery, electrode implantation, and field potential recording. In vivo electrophysiological recordings were then performed to measure population spike (PS) amplitude and excitatory postsynaptic potential (EPSP) slope in the hippocampal dentate gyrus. Long-term potentiation (LTP) was induced by high-frequency stimulation of the perforant pathway. Blood samples were then collected to measure plasma levels of triglycerides, low-density lipoproteins, very low-density lipoprotein, and cholesterol. After induction of LTP, PS amplitude and EPSP slope were significantly decreased in Aβ-injected rats fed a HFD compared to vehicle-injected animals or untreated animals that were fed a normal diet. Met treatment of Aβ-injected rats significantly attenuated these decreases, suggesting that Met decreased the effects of Aβ on LTP. These findings suggest that Met treatment is neuroprotective against the detrimental effects of Aβ and HFDs on hippocampal synaptic plasticity.

Streptozotocin Intracerebroventricular-Induced Neurotoxicity and Brain Insulin Resistance: a Therapeutic Intervention for Treatment of Sporadic Alzheimer's Disease (sAD)-Like Pathology

Alzheimer's disease (AD) is a neurodegenerative disorder that is remarkably characterized by pathological hallmarks which include amyloid plaques, neurofibrillary tangles, neuronal loss, and progressive cognitive loss. Several well-known genetic mutations which are being used for the development of a transgenic model of AD lead to an early onset familial AD (fAD)-like condition. However, these settings are only reasons for a small percentage of the total AD cases. The large majorities of AD cases are considered as a sporadic in origin and are less influenced by a single mutation of a gene. The etiology of sporadic Alzheimer's disease (sAD) remains unclear, but numerous risk factors have been identified that increase the chance of developing AD. Among these risk factors are insulin desensitization/resistance state, oxidative stress, neuroinflammation, synapse dysfunction, tau hyperphosphorylation, and deposition of Aβ in the brain. Subsequently, these risk factors lead to development of sAD. However, the underlying molecular mechanism is not so clear. Streptozotocin (STZ) produces similar characteristic pathology of sAD such as altered glucose metabolism, insulin signaling, synaptic dysfunction, protein kinases such as protein kinase B/C, glycogen synthase-3β (GSK-3β) activation, tau hyperphosphorylation, Aβ deposition, and neuronal apoptosis. Further, STZ also leads to inhibition of Akt/PKB, insulin receptor (IR) signaling molecule, and insulin resistance in brain. These alterations mediated by STZ can be used to explore the underlying molecular and pathophysiological mechanism of AD (especially sAD) and their therapeutic intervention for drug development against AD pathology.

Proton pump inhibition increases rapid eye movement sleep in the rat

Increased bodily CO₂ concentration alters cellular pH as well as sleep. The proton pump, which plays an important role in the homeostatic regulation of cellular pH, therefore, may modulate sleep. We investigated the effects of the proton pump inhibitor “lansoprazole” on sleep-wakefulness. Male Wistar rats were surgically prepared for chronic polysomnographic recordings. Two different doses of lansoprazole (low: 1 mg/kg; high: 10 mg/kg) were injected intraperitoneally in the same animal (n = 7) and sleep-wakefulness was recorded for 6 hrs. The changes in sleep-wakefulness were compared statistically. Percent REM sleep amount in the vehicle and lansoprazole low dose groups was 9.26 ± 1.03 and 9.09 ± 0.54, respectively, which increased significantly in the lansoprazole high dose group by 31.75% (from vehicle) and 34.21% (from low dose). Also, REM sleep episode numbers significantly increased in lansoprazole high dose group. Further, the sodium-hydrogen exchanger blocker “amiloride” (10 mg/kg; i.p.) (n = 5) did not alter sleep-wake architecture. Our results suggest that the proton pump plays an important role in REM sleep modulation and supports our view that REM sleep might act as a sentinel to help maintain normal CO₂ level for unperturbed sleep.