Scopolamine model of dementia: electroencephalogram findings and cognitive performance

Electroencephalographic Measures of Delirium in the Perioperative Setting: A Systematic Review

Postoperative delirium (POD) is frequent in older adults and is associated with adverse cognitive and functional outcomes. In the last several decades, there has been an increased interest in exploring tools that easily allow the early recognition of patients at risk of developing POD. The electroencephalogram (EEG) is a widely available tool used to understand delirium pathophysiology, and its use in the perioperative setting has grown exponentially, particularly to predict and detect POD. We performed a systematic review to investigate the use of EEG in the pre-, intra-, and postoperative settings. We identified 371 studies, and 56 met the inclusion criteria. A range of techniques was used to obtain EEG data, from limited 1-4 channel setups to complex 256-channel systems. Power spectra were often measured preoperatively, yet the outcomes were inconsistent. During surgery, the emphasis was primarily on burst suppression (BS) metrics and power spectra, with a link between the frequency and timing of BS, and POD. The EEG patterns observed in POD aligned with those noted in delirium in different contexts, suggesting a reduction in EEG activity. Further research is required to investigate preoperative EEG indicators that may predict susceptibility to delirium.

Zebrafish models for studying cognitive enhancers

Cognitive decline is commonly seen both in normal aging and in neurodegenerative and neuropsychiatric diseases. Various experimental animal models represent a valuable tool to study brain cognitive processes and their deficits. Equally important is the search for novel drugs to treat cognitive deficits and improve cognitions. Complementing rodent and clinical findings, studies utilizing zebrafish (Danio rerio) are rapidly gaining popularity in translational cognitive research and neuroactive drug screening. Here, we discuss the value of zebrafish models and assays for screening nootropic (cognitive enhancer) drugs and the discovery of novel nootropics. We also discuss the existing challenges, and outline future directions of research in this field.

Resting state electroencephalographic alpha rhythms are sensitive to Alzheimer's disease mild cognitive impairment progression at a 6-month follow-up

Are posterior resting-state electroencephalographic (rsEEG) alpha rhythms sensitive to the Alzheimer's disease mild cognitive impairment (ADMCI) progression at a 6-month follow-up? Clinical, cerebrospinal, neuroimaging, and rsEEG datasets in 52 ADMCI and 60 Healthy old seniors (equivalent groups for demographic features) were available from an international archive (www.pdwaves.eu). The ADMCI patients were arbitrarily divided into two groups: REACTIVE and UNREACTIVE, based on the reduction (reactivity) in the posterior rsEEG alpha eLORETA source activities from the eyes-closed to eyes-open condition at ≥ -10% and -10%, respectively. 75% of the ADMCI patients were REACTIVE. Compared to the UNREACTIVE group, the REACTIVE group showed (1) less abnormal posterior rsEEG source activity during the eyes-closed condition and (2) a decrease in that activity at the 6-month follow-up. These effects could not be explained by neuroimaging and neuropsychological biomarkers of AD. Such a biomarker might reflect abnormalities in cortical arousal in quiet wakefulness to be used for clinical studies in ADMCI patients using 6-month follow-ups.

Alignments between cortical neurochemical systems, proteinopathy and neurophysiological alterations along the Alzheimer's disease continuum

Two neuropathological hallmarks of Alzheimer's disease (AD) are the accumulation of amyloid-β (Aβ) proteins and alterations in cortical neurophysiological signaling. Despite parallel research indicating disruption of multiple neurotransmitter systems in AD, it has been unclear whether these two phenomena are related to the neurochemical organization of the cortex. We leveraged task-free magnetoencephalography and positron emission tomography, with a cortical atlas of 19 neurotransmitters to study the alignment and interactions between alterations of neurophysiological signaling, Aβ deposition, and the neurochemical gradients of the human cortex. In patients with amnestic mild cognitive impairment (N = 18) and probable AD (N = 20), we found that changes in rhythmic, but not arrhythmic, cortical neurophysiological signaling relative to healthy controls (N = 20) are topographically aligned with cholinergic, serotonergic, and dopaminergic neurochemical systems. These neuro-physio-chemical alignments are related to the severity of cognitive and behavioral impairments. We also found that cortical Aβ plaques are preferentially deposited along neurochemical boundaries, and mediate how beta-band rhythmic cortical activity maps align with muscarinic acetylcholine receptors. Finally, we show in an independent dataset that many of these alignments manifest in the asymptomatic stages of cortical Aβ accumulation (N = 33; N = 71 healthy controls), particularly the Aβ-neurochemical alignments (57.1%) and neuro-physio-chemical alignments in the alpha frequency band (62.5%). Overall, the present study demonstrates that the expression of pathology in pre-clinical and clinical AD aligns topographically with the cortical distribution of chemical neuromodulator systems, scaling with clinical severity and with implications for potential pharmacotherapeutic pathways.

Regulation mechanisms of sea cucumber peptides against scopolamine-induced memory disorder and novel memory-improving peptides identification

Memory impairment affects cognition and information processing, and attention, leading to a decline in life quality of patients. Previous studies have shown the memory-improving effects of sea cucumber peptides. This study further explored the memory-improving mechanisms of sea cucumber peptides using scopolamine-induced memory-impaired mice and identified novel memory-improving peptides within low molecular weight peptide fractions. The sea cucumber peptides were categorized into three groups based on their molecular weights: SCP-L (molecular weight greater than 10 kDa), SCP-M (weight between 3 kDa and 10 kDa), and SCP-S (molecular weight less than 3 kDa). The results showed that SCP-S improved behavioral performance by regulating cholinergic system disorder and reducing oxidative stress levels, distinguishing itself from SCP-M and SCP-L. Further, SCP-S was found to exhibit a well ability in alleviating the degree of neuroinflammation dependent on microglia and promoting synaptic plasticity. Additionally, a novel memory-improving peptide Ser-Phe-Gly-Asp-Ile (SFGDI) was identified by EASY-nano-LC/MS/MS after simulated digestion-absorption coupling of in silico technologies from SCP-S. SFGDI protected against oxidative stress and regulated cholinergic system in scopolamine-induced PC12 cells. These findings suggest that SCP-S and SFGDI might be considered as potential memory-improving food for people suffering from memory disorders.

Preliminary investigation of the administration of biperiden to reduce relapses in individuals with cocaine/crack user disorder: A randomized controlled clinical trial

BACKGROUND

Several studies have demonstrated that ACh modulates the dopaminergic circuit in the nucleus accumbens, and its blockade appears to be associated with the inhibition of the reinforced effect or the increase in dopamine caused by cocaine use. The objective of this study was to evaluate the effect of biperiden (a muscarinic receptor antagonist with a relatively higher affinity for the M1 receptor) on crack/cocaine use relapse compared to a control group that received placebo.

METHODS

This study is a double-blind, randomized, placebo-controlled clinical trial. The intervention group received 2 mg of biperiden, 3 times a day, for a period of 3 months. The control group received identical placebo capsules, at the same frequency and over the same period. All participants were followed for a period of six months.

RESULTS

The sample comprised 128 people, with 61 in the control group and 67 in the biperiden group. Lower substance consumption was observed in the group that received biperiden treatment two (bT2 = -2.2 [-3.3; -1.0], p < 0.001) and six months (bT4 = -6, 2 [-8.6; -3.9], p < 0.001) after the beginning of the intervention. The biperiden group had a higher latency until a possible first day of consumption, in the same evaluation periods (bT2 = 0.26 [0.080; 0.44], p = 0.004; bT4 = 0.63 [0.32; 0.93], p < 0.001).

CONCLUSIONS

Despite the major limitations of the present study, the group that received biperiden reduced the number of days of cocaine/crack use and showed an increase in the latency time for relapse. More studies are needed to confirm the utility of this approach.

Oscillatory characteristics of resting-state magnetoencephalography reflect pathological and symptomatic conditions of cognitive impairment

Background

Dementia and mild cognitive impairment are characterised by symptoms of cognitive decline, which are typically assessed using neuropsychological assessments (NPAs), such as the Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB). Magnetoencephalography (MEG) is a novel clinical assessment technique that measures brain activities (summarised as oscillatory parameters), which are associated with symptoms of cognitive impairment. However, the relevance of MEG and regional cerebral blood flow (rCBF) data obtained using single-photon emission computed tomography (SPECT) has not been examined using clinical datasets. Therefore, this study aimed to investigate the relationships among MEG oscillatory parameters, clinically validated biomarkers computed from rCBF, and NPAs using outpatient data retrieved from hospital records.

Methods

Clinical data from 64 individuals with mixed pathological backgrounds were retrieved and analysed. MEG oscillatory parameters, including relative power (RP) from delta to high gamma bands, mean frequency, individual alpha frequency, and Shannon's spectral entropy, were computed for each cortical region. For SPECT data, three pathological parameters-'severity', 'extent', and 'ratio'-were computed using an easy z-score imaging system (eZIS). As for NPAs, the MMSE and FAB scores were retrieved.

Results

MEG oscillatory parameters were correlated with eZIS parameters. The eZIS parameters associated with Alzheimer's disease pathology were reflected in theta power augmentation and slower shift of the alpha peak. Moreover, MEG oscillatory parameters were found to reflect NPAs. Global slowing and loss of diversity in neural oscillatory components correlated with MMSE and FAB scores, whereas the associations between eZIS parameters and NPAs were sparse.

Conclusion

MEG oscillatory parameters correlated with both SPECT (i.e. eZIS) parameters and NPAs, supporting the clinical validity of MEG oscillatory parameters as pathological and symptomatic indicators. The findings indicate that various components of MEG oscillatory characteristics can provide valuable pathological and symptomatic information, making MEG data a rich resource for clinical examinations of patients with cognitive impairments. SPECT (i.e. eZIS) parameters showed no correlations with NPAs. The results contributed to a better understanding of the characteristics of electrophysiological and pathological examinations for patients with cognitive impairments, which will help to facilitate their co-use in clinical application, thereby improving patient care.

Reliability of Spectral Features of Resting-State Brain Activity: A Magnetoencephalography Study

Background Cognition is a vital sign and its deterioration is a major concern in clinical medicine. It is usually evaluated using neuropsychological assessments, which have innate limitations such as the practice effect. To compensate for these assessments, the oscillatory power of resting-state brain activity has recently become available. The power is obtained noninvasively using magnetoencephalography and is summarized by spectral parameters such as the median frequency (MF), individual alpha frequency (IAF), spectral edge frequency 95 (SEF95), and Shannon's spectral entropy (SSE). As these parameters are less sensitive to practice effects, they are suitable for longitudinal studies. However, their reliability remains unestablished, hindering their proactive use in clinical practice. Therefore, we aimed to quantify the within-participant reliability of these parameters using repeated measurements of healthy participants to facilitate their clinical use and to evaluate the observed changes/differences in these parameters reported in previous studies. Methodology Resting-state brain activity with eyes closed was recorded using magnetoencephalography for five minutes from 15 healthy individuals (29.3 ± 4.6 years old: ranging from 23 to 28 years old). The following four spectral parameters were calculated: MF, IAF, SEF95, and SSE. To quantify reliability, the minimal detectable change (MDC) and intraclass correlation coefficient (ICC) were computed for each parameter. In addition, we used MDCs to evaluate the changes and differences in the spectral parameters reported in previous longitudinal and cross-sectional studies. Results The MDC at 95% confidence interval (MDC95) of MF, IAF, SEF95, and SSE were 0.61 Hz, 0.44 Hz, 2.91 Hz, and 0.028, respectively. The ICCs of these parameters were 0.96, 0.92, 0.94, and 0.83, respectively. The MDC95 of these parameters was smaller than the mean difference in the parameters between cognitively healthy individuals and patients with dementia, as reported in previous studies. Conclusions The spectral parameter changes/differences observed in prior studies were not attributed to measurement errors but rather reflected genuine effects. Furthermore, all spectral parameters exhibited high ICCs (>0.8), underscoring their robust within-participant reliability. Our results support the clinical use of these parameters, especially in the longitudinal monitoring and evaluation of the outcomes of interventions.

Acetylcholine and metacognition during sleep

Acetylcholine is a neurotransmitter and neuromodulator involved in a variety of cognitive functions. Additionally, acetylcholine is involved in the regulation of REM sleep: cholinergic neurons in the brainstem and basal forebrain project to and innervate wide areas of the cerebral cortex, and reciprocally interact with other neuromodulatory systems, to produce the sleep-wake cycle and different sleep stages. Consciousness and cognition vary considerably across and within sleep stages, with metacognitive capacity being strikingly reduced even during aesthetically and emotionally rich dream experiences. A notable exception is the phenomenon of lucid dreaming-a rare state whereby waking levels of metacognitive awareness are restored during sleep-resulting in individuals becoming aware of the fact that they are dreaming. The role of neurotransmitters in these fluctuations of consciousness and cognition during sleep is still poorly understood. While recent studies using acetylcholinesterase inhibitors suggest a potential role of acetylcholine in the occurrence of lucid dreaming, the underlying mechanisms by which this effect is produced remains un-modelled and unknown; with the causal link between cholinergic mechanisms and upstream psychological states being complex and elusive. Several theories and approaches targeting the association between acetylcholine and metacognition during wakefulness and sleep are highlighted in this review, moving through microscopic, mesoscopic and macroscopic levels of analysis to detail this phenomenon at several organisational scales. Several exploratory hypotheses will be developed to guide future research towards fully articulating how metacognition is affected by activity at the acetylcholine receptor.

Neuroprotective, neurogenic, and anticholinergic evidence of Ganoderma lucidum cognitive effects: Crucial knowledge is still lacking

Ganoderma lucidum is a mushroom that has been widely used for centuries in Asian countries for its antiaging properties. It is popularly known as "Ling Zhi," "Reishi," and "Youngzhi," and because of its benefits, it is known as the "immortality mushroom." Pharmacological assays have revealed that G. lucidum ameliorates cognitive impairments through inhibition of β-amyloid and neurofibrillary tangle formation, antioxidant effect, reduction of inflammatory cytokine release and apoptosis, genic expression modulation, among other activities. Chemical investigations on G. lucidum have revealed the presence of metabolites such as triterpenes, which are the most explored in this field, as well as flavonoids, steroids, benzofurans, and alkaloids; in the literature, these have also been reported to have mnemonic activity. These properties of the mushroom make it a potential source of new drugs to prevent or reverse memory disorders, as actual medications are able to only alleviate some symptoms but are unable to stop the progress of cognitive impairments, with no impact on social, familiar, and personal relevance. In this review, we discuss the cognitive findings of G. lucidum reported in the literature, converging the proposed mechanisms through the several pathways that underlie memory and cognition processes. In addition, we highlight the gaps that deserve particular attention to support future studies.

Discovery of Multitarget-Directed Ligands from Piperidine Alkaloid Piperine as a Cap Group for the Management of Alzheimer's Disease

The naturally inspired multitarget-directed ligands (PC01-PC10 and PD01-PD26) were synthesized from piperine for the management of Alzheimer's disease (AD). The compound PD07 showed significant inhibitory activity on ChEs, BACE1, and Aβ1-42 aggregation in in vitro studies. Further, compound PD07 effectively displaced the propidium iodide at the AChE PAS site. The compound PD07 exhibited significant lipophilicity in PAMPA studies. Additionally, PD07 demonstrated neuroprotective properties in the Aβ1-42 induced SH-SY5Y cell line. Furthermore, DFT calculations were performed using B3LYP/6-311G(d,p) basis sets to explore the PD07 physical and chemical properties. The compound PD07 showed a similar binding interaction profile at active sites of AChE, BuChE, and BACE1 proteins as compared to reference ligands (donepezil, tacrine, and BSD) in molecular docking and dynamic simulation studies. In acute oral toxicity studies, compound PD07 exhibited no toxicity symptoms up to 300 mg/kg, po. The compound PD07 (10 mg/kg, po) improved memory and cognition in scopolamine-induced amnesia rats. Further, PD07 increased ACh levels in the brain by inhibiting the AChE activity. The results from in vitro, in silico, and in vivo studies suggested that compound PD07 is a potent multitarget-directed lead from piperine to overcome Alzheimer's disease.

The acute effects of psychoactive drugs on emotional episodic memory encoding, consolidation, and retrieval: A comprehensive review

Psychoactive drugs modulate learning and emotional processes in ways that could impact their recreational and medical use. Recent work has revealed how drugs impact different stages of processing emotional episodic memories, specifically encoding (forming memories), consolidation (stabilizing memories), and retrieval (accessing memories). Drugs administered before encoding may preferentially impair (e.g., GABAA sedatives including alcohol and benzodiazepines, Δ9-tetrahydrocannabinol or THC, ketamine), enhance (e.g., dextroamphetamine and dextromethamphetamine), or both impair and enhance (i.e., ± 3,4-methylenedioxymethylamphetamine or MDMA) emotionally negative and positive compared to neutral memories. GABAA sedatives administered immediately post-encoding (during consolidation) can preferentially enhance emotional memories, though this selectivity may decline or even reverse (i.e., preferential enhancement of neutral memories) as the delay between encoding and retrieval increases. Finally, retrieving memories under the effects of THC, dextroamphetamine, MDMA, and perhaps GABAA sedatives distorts memory, with potentially greater selectively for emotional (especially positive) memories. We review these effects, propose neural mechanisms, discuss methodological considerations for future work, and speculate how drug effects on emotional episodic memory may contribute to drug use and abuse.

The Effect of Ethanol Extract from Mesua ferrea Linn Flower on Alzheimer's Disease and Its Underlying Mechanism

The effects of Mesua ferrea Linn flower (MFE) extract on the pathogenic cascade of Alzheimer's disease (AD) were determined by an in vitro and cell culture model in the search for a potential candidate for the treatment of AD. The 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay exhibited that the MFE extract had antioxidant activities. According to the Ellman and the thioflavin T method's result, the extracts could inhibit acetylcholinesterase and β-amyloid (Aβ) aggregation. Studies on neuroprotection in cell culture found that the MFE extract could reduce the death of human neuroblastoma cells (SH-SY5Y) caused by H₂O₂ and Aβ. Western blot analysis exhibited that the MFE extract alleviated H₂O₂-induced neuronal cell damage by downregulating the pro-apoptotic proteins, including cleaved caspase-3, Bax, and by enhancing the expression of anti-apoptotic markers including MCl₁, BCl_xl, and survivin. Moreover, MFE extract inhibited the expression of APP, presenilin 1, and BACE, and increased the expression of neprilysin. In addition, the MFE extract could enhance scopolamine-induced memory deficit in mice. Overall, results showed that the MFE extract had several modes of action related to the AD pathogenesis cascade, including antioxidants, anti-acetylcholinesterase, anti-Aβ aggregation, and neuroprotection against oxidative stress and Aβ. Therefore, the M. ferrea L. flower might be a possibility for further development as a medication for AD.

Discovery of multi-target directed 3-OH pyrrolidine derivatives through a semisynthetic approach from alkaloid vasicine for the treatment of Alzheimer's disease

Vasicine is a pyrroloquinazoline alkaloid, which has been isolated from the plant Adhatoda vasica. Naturally inspired semi-synthetic transformations were prepared using vasicine as a synthetic precursor to overcome Alzheimer's disease (AD). These semi-synthetic analogs exhibited stable interactions and were well resided at AChE and BChE active sites in in-silico studies. Further, in-vitro experiments were performed to assess the cholinesterase inhibitory activity and reduction of amyloid-beta (Aβ_1-42) plaques potency, PAMPA assay permeability, and antioxidant activity, these findings suggested that compound VA10 can be a lead molecule among all the synthesized analogs. The compound VA10 binds towards AChE peripheral anionic site (PAS) property was established through propidium iodide displacement assay. Moreover, VA10 showed no notable cytotoxicity and exhibited neuroprotective nature on Aβ_1-42 treated SH-SY5Y cell line. In addition, VA10 was found to be safe in rats, which was confirmed by acute oral toxicity studies. Furthermore, in-vivo studies suggested that compound VA10 (10 mg/kg, p.o) ameliorated the memory and cognition impairment in scopolamine-induced amnesia model and Aβ_1-42 induced Alzheimer rat model. Ex-vivo studies of compound VA10 demonstrate improved ACh levels by inhibiting AChE activity in rat brain. Moreover, histopathological observations on rats brain sections indicate VA10 (10 mg/kg, p.o) recovered the neuronal cells at hippocampus region (DG, CA3, and CA1). These positive experimental data from in-silico, in-vitro and in-vivo studies, suggested that compound VA10 can be a lead compound for further preclinical development studies as a naturally derived alkaloid for anti-AD.

Cognitive Enhancing Activity of Fermented Aloe arborescens Extract on Scopolamine-induced Memory Impairment in Mice

Background

Alzheimer’s disease (AD) is a type of dementia that leads to loss of memory and learning ability. Aloe arborescens is a traditional medicinal plant in Europe and Africa. It has been reported that A. arborescens showed anti-inflammatory, anti-cancer, antioxidant, and anti-obesity effects. Previously, we reported that fermented A. arborescens extract had neuroprotective activity in glutamate-insulted HT22 cells.

Materials and Methods

In this study, we evaluated its cognitive enhancing activity by using scopolamine-induced memory impairment in mice as a model system. Morris water maze test was carried out to evaluate spatial memory enhancing activity and a passive avoidance test was performed to evaluate an effect on learning memory. A. arborescens was extracted with methanol in an ultrasonic extraction device and fermented with Lactobacillus brevis. Fermented A. arborescens extract was treated to scopolamine-insulted Institute of Cancer Research (ICR) mice at a concentration of 100, 200, and 300 mg/kg, respectively.

Results

The fermented A. arborescens extract significantly improved the scopolamine-insulted memory impairment. Fermented A. arborescens extract inhibited acetylcholine esterase activity and boosted brain-derived neurotrophic factor and phosphorylated cAMP-response element-binding protein (p-CREB) expression. These results showed that fermented AA extract improved memory impairment through the increase of the BDNF and p-CREB signal pathway.

Conclusion

According to these results, we considered that the fermented A. arborescens extract can be a useful candidate for new nutraceuticals for improving memory impairment.

Differences in bioavailability and cognitive-enhancing activity exerted by different crystal polymorphs of latrepirdine (Dimebon®)

Introduction: Pharmacokinetic characteristics as well as cognitive-enhancing nootropic activity of latrepirdine (Dimebon^®) in relationship with its polymorphic forms have been studied in SD and Wistar rats. Methods: The pharmacokinetics of six polymorphs (A, B, C, D, E, F) of latrepirdine were studied in male SD rats after 7 days of oral administration in corn oil at a dose of 10 mg/kg once a day. Blood and brain samples were taken on the 7th day of administration at 15 min, 30 min, 60 min and 120 min after administration and analyzed for latrepirdine content by LC-MS. The cognitive-enhancing nootropic effect was studied in male and female Wistar rats after 9 days of oral administration in corn oil at a dose of 10 mg/kg, after prior administration of scopolamine, an agent that causes memory impairment similar to that in Alzheimer's disease. The animals' cognitive function was studied in the passive avoidance test. Results: When studying the pharmacokinetics, the highest bioavailability both in the blood and in the brain was demonstrated by polymorph E, whose AUC was the highest relative to other polymorphs. In the study of the cognitive-enhancing nootropic effect, polymorph E also showed the highest activity, whose values of the latent period of entering the dark chamber did not differ from control animals, and differed from other polymorphs. Conclusion: Thus, the crystal structure has been shown to play a key role in the bioavailability and efficacy of latrepirdine, and polymorph E has also been shown to be a promising drug for the treatment of neurodegenerative diseases associated with memory impairment, such as Alzheimer's disease.

Back to the Future of Neuropsychopharmacology

Disappointments in translating preclinical findings into clinical efficacy have triggered a number of changes in neuroscience drug discovery ranging from investments diverted to other therapeutic areas to reduced reliance on efficacy claims derived from preclinical models. In this chapter, we argue that there are several existing examples that teach us on what needs to be done to improve the success rate. We advocate the reverse engineering approach that shifts the focus from preclinical efforts to "model" human disease states to pharmacodynamic activity as a common denominator in the journey to translate clinically validated phenomena to preclinical level and then back to humans. Combined with the research rigor, openness, and transparency, this reverse engineering approach is well set to bring new effective and safe medications to patients in need.

Polyphenols from Conyza dioscoridis (L.) ameliorate Alzheimer’s disease- like alterations through multi-targeting activities in two animal models

Background

Recent investigations suggested that anticancer agents may inhibit the progression of Alzheimer's disease (AD) pathology. Conyza dioscoridis (L.) was demonstrated to have anticancer, antioxidant, anti-inflammatory and antidiabetic effects. This study was carried out to investigate the efficacy of polyphenols from Conyza dioscoridis (L.) extract (PCDE) on AD.

Methods

Impacts of 3 doses of PCDE and donepezil, a reference drug, on the features of Alzheimer's disease in two animal models were investigated.

Results

PCDE ameliorated the memory and learning impairment shown in rats following a single dose of scopolamine (scopolamine model) or 17 weeks of high-fat/high-fructose(HF/Hfr) diet coupled with a single dose of streptozotocin, (25 mg/kg) (T2D model). They reduced significantly the high hippocampal cholinesterase activity in the two models of rats. Administration of PCDE for 8 weeks in the T2D model showed a significant reduction in hippocampal GSK-3β, caspase-3 activity and increase in the inhibited glutamate receptor expression (AMPA GluR1 subunit and NMDA receptor subunits NR1, NR2A, NR2B). A significant reduction of HOMA-insulin resistance and serum hypercholesterolemia was observed. The Tau hyperphosphorylation and Aβ 1–42 generation in the hippocampal of T2D rats were significantly decreased by PCDE. Modulation of the oxidative stress markers, (rise in GH and SOD; decrease in MDA levels) and a significant reduction of TNF-α and IL-1β in the hippocampus of T2D rats treated by PCDE extract were important findings in this study. The highest dose tested was 4% of the highest safe dose.

Conclusion

Our study suggests that PCDE is multi-targeting agent with multiple beneficial activities in combating features of AD. This study may provide a novel therapeutic strategy for AD treatment that warrants clinical studies.

Behavioral and Molecular Effects of Thapsigargin-Induced Brain ER- Stress: Encompassing Inflammation, MAPK, and Insulin Signaling Pathway

Accumulation of misfolded proteins, known as endoplasmic reticulum (ER) stress, is known to participate in Alzheimer’s disease (AD). AD is also correlated with impaired central insulin signaling. However, few studies have probed the relationship between memory, central ER stress, inflammation, hippocampal mitogen-activated protein kinase (MAPK) activity and insulin resistance. The present study aimed to investigate the causative role and underlying mechanisms of brain ER stress in memory impairment and develop a reliable animal model for ER-mediated memory loss. Thapsigargin (TG), a known ER stress activator, was centrally administered. The cognitive function of animals was evaluated by the Morris Water Maze (MWM). To verify the induction of central ER stress, we investigated the mRNA expression of UPR markers in the hippocampus. In addition, the activation of ER stress markers, including Bip, CHOP, and some related apoptosis and pro-inflammatory proteins, such as caspase-3, Bax, Bcl-2, TNF-α, MAPK, and insulin signaling markers, were assessed by Western-blots. The results demonstrated that TG impairs spatial cognition and hippocampal insulin signaling. Meanwhile, molecular results showed a concurrent increment of hippocampal UPR markers, apoptosis, P38 activity, and TNF-α. This study introduced TG-induced ER stress as a pharmacological model for memory impairment in rats and revealed some underlying mechanisms.

Multifunctionality of Clausena harmandiana Extract and Its Active Constituents against Alzheimer's Disease

This study was designed to investigate the effects of the root-bark extract of Clausena harmandiana (CH) and its active constituents (nordentatin and 7-methoxyheptaphylline) on pharmacological activities regarding selected targets associated with AD, namely, its antioxidant activity, inhibition of Aβ aggregation, acetylcholinesterase (AChE) activity, and neuroprotective effects. The effect of the CH extract on the cognitive impairment induced by scopolamine was also evaluated in mice. The effects of the CH extract and its active constituents on radical scavenging, Aβ aggregation, and AChE activity were investigated with a 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) assay, a thioflavin-T assay, and Ellman’s method. The neuroprotective effects of the extract against hydrogen-peroxide and Aβ toxicity were evaluated with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. In addition, the effects on cognitive impairment induced by scopolamine in mice were evaluated using Morris-water-maze and modified-Y-maze test models. The results of the present study demonstrate that the root-bark extract of CH shows multimodal actions relevant to the AD pathological cascade, including antioxidant effects, the inhibition of Aβ aggregation, the inhibition of AChE function, and neuroprotection against oxidative stress and Aβ toxicity. The extracts could improve both the short- and long-term memory deficits induced by scopolamine in mice.

Cholinergic models of memory impairment in animals and man: scopolamine vs. biperiden

Scopolamine has been used as a pharmacologic model for cognitive impairments in dementia and Alzheimer's disease. The validity of this model seems to be limited because findings in animals do not readily translate to novel treatments in humans. Biperiden is also a cholinergic deficit model for cognitive impairments but specifically blocks muscarinic M1 receptors. The effects of scopolamine and biperiden (and pirenzepine) are compared in animal studies and related to findings in humans. It is concluded that the effects on cognitive functions are different for scopolamine and biperiden, and they should be considered as different cognitive deficit models. Scopolamine may model more advanced stages of Alzheimer's disease whereas biperiden may model the early deficits in declarative memory in aging and mild cognitive impairment.

Response-related sensorimotor rhythms under scopolamine and MK-801 exposures in the touchscreen visual discrimination test in rats

The human mu rhythm has been suggested to represent an important function in information processing. Rodent homologue rhythms have been assumed though no study has investigated them from the cognitive aspect yet. As voluntary goal-directed movements induce the desynchronization of mu rhythm, we aimed at exploring whether the response-related brain activity during the touchscreen visual discrimination (VD) task is suitable to detect sensorimotor rhythms and their change under cognitive impairment. Different doses of scopolamine or MK-801 were injected subcutaneously to rats, and epidural electroencephalogram (EEG) was recorded during task performance. Arciform ~ 10 Hz oscillations appeared during visual processing, then two characteristic alpha/beta desynchronization-resynchronization patterns emerged mainly above the sensorimotor areas, serving presumably different motor functions. Beyond causing cognitive impairment, both drugs supressed the touch-related upper alpha (10–15 Hz) reactivity for desynchronization. Reaction time predominantly correlated positively with movement-related alpha and beta power both in normal and impaired conditions. These results support the existence of a mu homologue rodent rhythm whose upper alpha component appeared to be modulated by cholinergic and glutamatergic mechanisms and its power change might indicate a potential EEG correlate of processing speed. The VD task can be utilized for the investigation of sensorimotor rhythms in rats.

Potential for non-starch polysaccharides in the prevention and remediation of cognitive impairment: A comprehensive review

Non-starch polysaccharides (NSPs) are food ingredients proven to be beneficial in a large number of health issues. However, there is no literature systematic review about the effects and corresponding mechanisms of NSPs on the prevention and remediation of cognitive impairment. In this review, studies on prevention and remediation of NSPs for cognitive deficit caused by diseases, menopause, ageing, chronic stress and environmental pollutants were summarized and the corresponding mechanisms were established. The anti-cognitive deficit effects of NSPs were associated with the modulation of amyloid β (Aβ) deposition, p-Tau aggregation, oxidative stress, inflammation, neuron apoptosis, neurogenesis, neurotransmitters, synaptic plasticity, autophagy and gut microbiota. Although the structure-function relationship has not been elucidated, several structural properties of NSPs such as molecular weight, sulfate content, hydroxyl group content, monosaccharide composition and molecular chain linkage might be crucial for the anti-cognitive deficit property. Notably, this review revealed that NSPs had a positive effect on cognitive impairment and proposed the future perspectives for further research on the anti-cognitive dysfunction effects of NSPs.

Emerging Electroencephalographic Biomarkers to Improve Preclinical to Clinical Translation in Alzheimer’s Disease

Continually emerging data indicate that sub-clinical, non-convulsive epileptiform activity is not only prevalent in Alzheimer’s disease (AD) but is detectable early in the course of the disease and predicts cognitive decline in both humans and animal models. Epileptiform activity and other electroencephalographic (EEG) measures may hold powerful, untapped potential to improve the translational validity of AD-related biomarkers in model animals ranging from mice, to rats, and non-human primates. In this review, we will focus on studies of epileptiform activity, EEG slowing, and theta-gamma coupling in preclinical models, with particular focus on its role in cognitive decline and relevance to AD. Here, each biomarker is described in the context of the contemporary literature and recent findings in AD relevant animal models are discussed.

Neuromodulatory Mechanisms of a Memory Loss-Preventive Effect of Alpha-Lipoic Acid in an Experimental Rat Model of Dementia

This study evaluates some of the neuromodulatory mechanisms of the memory loss preventive effect of alpha-lipoic acid (ALA) in a scopolamine (Sco)-induced rat model of Alzheimer's disease (AD) type dementia. Our results confirmed that Sco administration induces significant memory impairment, worsens exploratory behaviour and habituation, increases acetylcholinesterase (AChE) activity, and induces pathological monoamine content changes in the prefrontal cortex and hippocampus. ALA administration largely prevented Sco-induced memory impairment. It also improved exploratory behaviour and preserved habituation, and it decreased AChE activity, reversing it to control group levels, and corrected aberrant monoamine levels in the prefrontal cortex and hippocampus. According to the data available, this is the first time that ALA-induced changes in AChE and monoamine levels in the prefrontal cortex and hippocampus (brain structures related to learning and memory) have been demonstrated in a Sco-induced rat model of AD type dementia.

Sea Cucumber-Derived Peptide Attenuates Scopolamine-Induced Cognitive Impairment by Preventing Hippocampal Cholinergic Dysfunction and Neuronal Cell Death

The incidence of neurodegenerative diseases related to cognitive decline and memory loss is on the rise as the global elderly population increases. In this study, we evaluated the effect of the sea cucumber-derived peptide Phe-Tyr-Asp-Trp-Pro-Lys (FYDWPK) on scopolamine-induced neurotoxicity in an animal model. The Morris water maze, passive avoidance apparatus, and shuttle box test were used to assess learning and memory abilities. In behavioral tests, FYDWPK effectively alleviated learning and memory impairment. FYDWPK also alleviated cholinergic dysfunction in mice with dementia. Furthermore, FYDWPK significantly improved oxidative imbalance by increasing superoxide dismutase activity and decreasing malondialdehyde levels (P < 0.05). The pathological results showed that FYDWPK alleviated neuronal loss, blurred caryotheca, and pyknotic nuclei in the hippocampus, and a high dose of FYDWPK had the best effect. In conclusion, FYDWPK alleviated cognitive and memory impairments by regulating oxidative imbalance, reducing cholinergic dysfunction, and relieving pathological alterations.

Research progress on risk factors of delirium in burn patients: A narrative review

Delirium, an acute brain dysfunction, is a common and serious complication in burn patients. The occurrence of delirium increases the difficulty of patient treatment, is associated with various adverse outcomes, and increases the burden on the patient's family. Many scholars have studied the factors that cause delirium, but the causes, pathogenesis, and treatment of delirium in burn patients have not been fully revealed. There is no effective pharmacological treatment for delirium, but active preventive measures can effectively reduce the incidence of delirium in burn patients. Therefore, it is necessary to study the relevant factors affecting the occurrence of delirium in burn patients. This study was conducted on December 20, 2021 by searching the PubMed database for a narrative review of published studies. The search strategy included keywords related to "burns," "delirium," and "risk factors." We reviewed the characteristics of delirium occurrence in burn patients and various delirium assessment tools, and summarized the risk factors for the development of delirium in burn patients in terms of personal, clinical, and environmental factors, and we found that although many risk factors act on the development of delirium in burn patients, some of them, such as clinical and environmental factors, are modifiable, suggesting that we can estimate the exposure of burn patients to risk factors by assessing their likelihood of delirium occurring and to make targeted interventions that provide a theoretical basis for the prevention and treatment of burn delirium.

Dietary supplementation with Ceriporia lacerata improves learning and memory in a scopolamine-induced amnesia mouse model

Ceriporia lacerata (CL) is a species of white rot fungi. In this study, we have examined the beneficial effect of CL on scopolamine-induced memory impairment in mice. A freeze-dried CL mycelial culture broth was dissolved and orally administered to scopolamine-treated C57BL/6J mice followed by behavioral tests using the Y-maze, passive avoidance, and Morris water maze tasks. CL administration at a daily dose of 200 mg/kg body weight resulted in restoration of exploration reduction and improvement of associative and spatial learning and memory impairment in scopolamine-treated mice. Concomitantly, heme oxygenase-1 was highly expressed in the hippocampal region of CL-administered mice. Moreover, the ethanolic extract of CL significantly increased the transcriptional activity of antioxidant response element and attenuated the glutamate-induced cytotoxicity in HT22 mouse hippocampal neuronal cells. These findings suggest that the CL intake can confer a beneficial effect on learning and memory presumably through protecting hippocampal neuronal cells from oxidative stress-induced damage.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10068-021-00945-5.

Deciphering the scopolamine challenge rat model by preclinical functional MRI

During preclinical drug testing, the systemic administration of scopolamine (SCO), a cholinergic antagonist, is widely used. However, it suffers important limitations, like non-specific behavioural effects partly due to its peripheral side-effects. Therefore, neuroimaging measures would enhance its translational value. To this end, in Wistar rats, we measured whisker-stimulation induced functional MRI activation after SCO, peripherally acting butylscopolamine (BSCO), or saline administration in a cross-over design. Besides the commonly used gradient-echo echo-planar imaging (GE EPI), we also used an arterial spin labeling method in isoflurane anesthesia. With the GE EPI measurement, SCO decreased the evoked BOLD response in the barrel cortex (BC), while BSCO increased it in the anterior cingulate cortex. In a second experiment, we used GE EPI and spin-echo (SE) EPI sequences in a combined (isoflurane + i.p. dexmedetomidine) anesthesia to account for anesthesia-effects. Here, we also examined the effect of donepezil. In the combined anesthesia, with the GE EPI, SCO decreased the activation in the BC and the inferior colliculus (IC). BSCO reduced the response merely in the IC. Our results revealed that SCO attenuated the evoked BOLD activation in the BC as a probable central effect in both experiments. The likely peripheral vascular actions of SCO with the given fMRI sequences depended on the type of anesthesia or its dose.

Sulforaphane enhances long-term potentiation and ameliorate scopolamine-induced memory impairment

Increases in human life expectancy have led to increases in the prevalence of senile dementia and neurodegenerative diseases. This is a major problem because there are no curative treatments for these diseases, and patients with unmanaged cognitive and neurodegenerative symptoms experience many social problems. Sulforaphane is a type of organosulfur compound known as an isothiocyanate. It is derived from glucoraphanin, a compound found in cruciferous vegetables such as broccoli, brussels sprouts, and cabbages, via an enzymatic reaction that is triggered by plant damage (e.g., chewing). Sulforaphane exhibits activity against cancer, inflammation, depression, and severe cardiac diseases. It can also alleviate oxidative stress and neural dysfunction in the brain. However, there is insufficient knowledge about the electrophysiological and behavioral basis of the effects of sulforaphane on learning and memory. Therefore, we evaluated whether acute sulforaphane administration affected long-term potentiation (LTP) in organotypic cultured rat hippocampal tissues. We also measured the effect of sulforaphane on the performance of three behavioral tests, the Y-maze test, the passive avoidance test, and the Morris water maze, which assess short-term memory, avoidance memory, and short and long-term spatial memory, respectively. We found that sulforaphane increased the total field excitatory postsynaptic potential (fEPSP) in a dose-dependent manner after high frequency stimulation and attenuated scopolamine-induced interference of the fEPSP in the hippocampal CA1 area. Sulforaphane also restored cognitive function and inhibited memory impairment as indicated by the alleviation of the negative neurological effects of scopolamine, i.e, a lowered ratio of spontaneous alternation in the Y-maze, a reduced step-through latency in the passive avoidance test, and an increased navigation time in the Morris water maze. These results indicate that sulforaphane can effectively prevent the attenuation of LTP and cognitive abilities induced by cholinergic and muscarinic receptor blockade. Further research is warranted to explore the potential therapeutic and prophylactic utility of sulforaphane for improving learning and memory, especially in those suffering from neurodegenerative disorders.

Synergistic Neuroprotective Effects of Mature Silkworm and Angelica gigas Against Scopolamine-Induced Mild Cognitive Impairment in Mice and H2O2-Induced Cell Death in HT22 Mouse Hippocampal Neuronal Cells

We previously reported that mature Bombyx mori silkworm (SW) ameliorated scopolamine (Sco)-induced amnesia, and Angelica gigas (AG) prevented cognitive impairment. SW is known for its gastroprotective effects such as improving liver function and alleviating the effects of Parkinson's disease. AG is known for its neuroprotective effects and for lowering the effects of low-density lipoprotein cholesterol. However, the neuroprotective effect of combined SW and AG (SWA-1) treatment and the underlying molecular mechanism by which SWA-1 regulates neurodegenerative diseases remains unclear. We evaluated the neuroprotective effect of SWA-1 against Sco-induced mild cognitive impairment in mice and H₂O₂-induced cell death in HT22 mouse hippocampal neuronal cells and elucidated the underlying molecular mechanism. Morris water maze and Y-maze tests were performed to examine the learning and memory abilities of mice. The underlying molecular mechanism was investigated by using western blotting. We demonstrated that SWA-1 significantly protects against H₂O₂-induced cell death in HT22 mouse hippocampal neuronal cells. SWA-1 also significantly reversed Sco-induced spatial learning and memory impairment. Specifically, SWA-1 upregulates the protein levels of phosphorylated extracellular signal-related kinase (Erk1/2) and phosphorylated p38 MAP kinase (p38). SWA-1 remarkably decreased the apoptotic index Bax/Bcl2 expression in the hippocampus of Sco-treated mice. Our results suggest that SWA-1 may be administered as alternative therapy for cognitive impairment and neurodegenerative diseases and should be studied further in human trials.

Beneficial effects of angiotensin converting enzyme inhibition on scopolamine-induced learning and memory impairment in rats, the roles of brain-derived neurotrophic factor, nitric oxide and neuroinflammation

The effect of the brain-derived neurotrophic factor (BDNF), cytokines, and renin angiotensin system (RAS) on memory function have been demonstrated. In this study, the effects of RAS inhibitor captopril (Capto) on hippocampal BDNF, interleukin -6 (IL-6), oxidative stress indicators, and nitric oxide (NO) in scopolamine (Sco)-induced memory impairment in rats were examined. The groups were (1) control, (2) Sco in which Sco was applied 30 min prior to the behavioral tests, and (3-5) Sco-Capto 10, 50, and 100 groups, where Capto (10, 50, or 100 mg/kg), were applied 2 weeks prior to the experiment, as well as 30 min prior to each Sco injection. The Morris Water Maze (MWM) test was conducted, and BDNF, IL-6, NO metabolites, malondialdehyde (MDA), thiol, superoxide dismutase (SOD), and catalase (CAT) were measured. Sco increased the delay and distance to the platform in the MWM test (P < .01 to P < .001), while shortening the time and distance in the target area (P < .01 to P < .001). Additionally, Sco increased IL-6, NO metabolites, and MDA, while decreasing BDNF, thiol, SOD, and CAT (P < .01 to P < .001). Although the Capto reduced the latency and distance traveled to the platform (P < .05 to P < .001), it elevated the time and distance traveled in the target area (P < .05 to P < .01). Furthermore, Capto improved BDNF, thiol, SOD, and CAT levels, and decreased IL-6, NO metabolites, and MDA (P < .05 to P < .001). RAS has a role in learning and memory impairment due to cholinergic system dysfunction. The possible mechanism(s) are including its effects on BDNF, neuro-inflammation and oxidative stress.

Contributions of animal models of cognitive disorders to neuropsychopharmacology

Cognitive disorders and symptoms are key features of many mental and neurological diseases, with a large spectrum of impaired domains. Because of their possible evolution and detrimental functioning impact, they are a major pharmacological target for both symptomatic and disease-modifier drugs, while few cognitive enhancers have been marketed with an insufficient efficiency. It explains the need to model these cognitive disorders beyond the modelization of mental or neurological diseases themselves. According to the experimental strategy used to induce cognitive impairment, three categories of models have been identified: neurotransmission-driven models; pathophysiology-driven models; environment-driven models. These three categories of models reflect different levels of integration of endogenous and exogenous mechanisms underlying cognitive disorders in humans. Their comprehensive knowledge and illustration of their pharmacological modulation could help to propose a renewing strategy of drug development in central nervous system (CNS) field at a time when the academic and industrial invest seems to be declining despite the medical and social burden of brain diseases.

The novel DYRK1A inhibitor KVN93 regulates cognitive function, amyloid-beta pathology, and neuroinflammation

Regulating amyloid beta (Aβ) pathology and neuroinflammatory responses holds promise for the treatment of Alzheimer's disease (AD) and other neurodegenerative and/or neuroinflammation-related diseases. In this study, the effects of KVN93, an inhibitor of dual-specificity tyrosine phosphorylation-regulated kinase-1A (DYRK1A), on cognitive function and Aβ plaque levels and the underlying mechanism of action were evaluated in 5x FAD mice (a mouse model of AD). KVN93 treatment significantly improved long-term memory by enhancing dendritic synaptic function. In addition, KVN93 significantly reduced Aβ plaque levels in 5x FAD mice by regulating levels of the Aβ degradation enzymes neprilysin (NEP) and insulin-degrading enzyme (IDE). Moreover, Aβ-induced microglial and astrocyte activation were significantly suppressed in the KVN-treated 5xFAD mice. KVN93 altered neuroinflammation induced by LPS in microglial cells but not primary astrocytes by regulating TLR4/AKT/STAT3 signaling, and in wild-type mice injected with LPS, KVN93 treatment reduced microglial and astrocyte activation. Overall, these results suggest that the novel DYRK1A inhibitor KVN93 is a potential therapeutic drug for regulating cognitive/synaptic function, Aβ plaque load, and neuroinflammatory responses in the brain.

Electroacupuncture reduces scopolamine-induced amnesia via mediating the miR-210/SIN3A and miR-183/SIN3A signaling pathway

Background

The expression of SIN3A is closely correlated with electroacupuncture (EA) treatment efficacy of scopolamine-induced amnesia (SIA), but its underlying mechanisms remain to be further explored.

Methods

Quantitative real-time PCR was performed to analyze the expression of candidate microRNAs (miRNAs) and SIN3A mRNA in a rat model of SIA. Western blot was carried out to evaluate the differential expression of SIN3A proteins under different circumstances. Luciferase assay was used to explore the inhibitory role of certain miRNAs in SIN3A expression. A novel object recognition (NOR) test was performed to assess the memory function of SIA rats undergoing EA treatment. Immunohistochemistry was carried out to evaluate the expression of SIN3A in the hippocampus of SIA rats.

Results

Rno-miR-183-5p, rno-miR-34c-3p and rno-miR-210-3p were significantly up-regulated in SIA rats treated with EA. In addition, rno-miR-183-5p and rno-miR-210-3p exerted an inhibitory effect on SIN3A expression. EA treatment of SIA rats effectively restored the dysregulated expression of rno-miR-183-5p, rno-miR-210-3p and SIN3A. EA treatment also promoted the inhibited expression of neuronal IEGs including Arc, Egr1, Homer1 and Narp in the hippocampus of SIA rats. Accordingly, the NOR test also confirmed the effect of EA treatment on the improvement of memory in SIA rats.

Conclusion

In summary, the findings of this study demonstrated that scopolamine-induced amnesia was associated with downregulated expression of miR-210/miR-183 and upregulated expression of SIN3A. Furthermore, treatment with EA alleviated scopolamine-induced amnesia in rats and was associated with upregulated expression of miR-210/miR-183 and downregulated expression of SIN3A.

Delirium

Delirium, a syndrome characterized by an acute change in attention, awareness and cognition, is caused by a medical condition that cannot be better explained by a pre-existing neurocognitive disorder. Multiple predisposing factors (for example, pre-existing cognitive impairment) and precipitating factors (for example, urinary tract infection) for delirium have been described, with most patients having both types. Because multiple factors are implicated in the aetiology of delirium, there are likely several neurobiological processes that contribute to delirium pathogenesis, including neuroinflammation, brain vascular dysfunction, altered brain metabolism, neurotransmitter imbalance and impaired neuronal network connectivity. The Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) is the most commonly used diagnostic system upon which a reference standard diagnosis is made, although many other delirium screening tools have been developed given the impracticality of using the DSM-5 in many settings. Pharmacological treatments for delirium (such as antipsychotic drugs) are not effective, reflecting substantial gaps in our understanding of its pathophysiology. Currently, the best management strategies are multidomain interventions that focus on treating precipitating conditions, medication review, managing distress, mitigating complications and maintaining engagement to environmental issues. The effective implementation of delirium detection, treatment and prevention strategies remains a major challenge for health-care organizations globally.

Age and APOE genotype affect the relationship between objectively measured physical activity and power in the alpha band, a marker of brain disease

BACKGROUND

Electrophysiological studies show that reductions in power within the alpha band are associated with the Alzheimer's disease (AD) continuum. Physical activity (PA) is a protective factor that has proved to reduce AD risk and pathological brain burden. Previous research has confirmed that exercise increases power in the alpha range. However, little is known regarding whether other non-modifiable risk factors for AD, such as increased age or APOE ε4 carriage, alter the association between PA and power in the alpha band.

METHODS

The relationship between PA and alpha band power was examined in a sample of 113 healthy adults using magnetoencephalography. Additionally, we explored whether ε4 carriage and age modulate this association. The correlations between alpha power and gray matter volumes and cognition were also investigated.

RESULTS

We detected a parieto-occipital cluster in which PA positively correlated with alpha power. The association between PA and alpha power remained following stratification of the cohort by genotype. Younger and older adults were investigated separately, and only younger adults exhibited a positive relationship between PA and alpha power. Interestingly, when four groups were created based on age (younger-older adult) and APOE (E3/E3-E3/E4), only younger E3/E3 (least predicted risk) and older E3/E4 (greatest predicted risk) had associations between greater alpha power and higher PA. Among older E3/E4, greater alpha power in these regions was associated with improved memory and preserved brain structure.

CONCLUSION

PA could protect against the slowing of brain activity that characterizes the AD continuum, where it is of benefit for all individuals, especially E3/E4 older adults.

Dissociating cholinergic influence on alertness and temporal attention in primates in a simple reaction time paradigm

The ability to promptly respond to behaviourally relevant events depends on both general alertness and phasic changes in attentional state driven by temporal expectations. Using a variable foreperiod simple reaction time (RT) task in four adult male rhesus macaques, we investigated the role of the cholinergic system in alertness and temporal expectation. Foreperiod effects on RT reflect temporal expectation, while alertness is quantified as overall response speed. We measured these RT parameters under vehicle treatment and systemic administration of the muscarinic receptor antagonist scopolamine. We also investigated whether and to what extent the effects of scopolamine were reversed by donepezil, a cholinesterase inhibitor widely used for the treatment of dementia. In the control condition, RT showed a continuous decrease as the foreperiod duration increased, which clearly indicated the effect of temporal expectation on RT. This foreperiod effect was mainly detectable on the faster tail of the RT distribution and was eliminated by scopolamine. Furthermore, scopolamine treatment slowed down the average RT. Donepezil treatment was efficient on the slower tail of the RT distribution and improved scopolamine-induced impairments only on the average RT reflecting a general beneficial effect on alertness without any improvement in temporal expectation. The present results highlight the role of the cholinergic system in temporal expectation and alertness in primates and help delineate the efficacy and scope of donepezil and other cholinomimetic agents as cognitive enhancers in present and future clinical practice.

Biperiden Selectively Impairs Verbal Episodic Memory in a Dose- and Time-Dependent Manner in Healthy Subjects

PURPOSE/BACKGROUND

Biperiden is a muscarinic antagonist that produces memory impairments without impairing attention or motor functions in healthy subjects. It has been suggested that a biperiden-induced memory deficit could model age- and dementia-related memory impairments. The goal of the current study was to determine the dose- and time-dependent effects of biperiden on cognition in healthy volunteers.

METHODS/PROCEDURES

Twenty-one healthy volunteers participated in a placebo-controlled, 3-way, crossover study. After a baseline test, cognitive performance was tested at 3 time points after a single dose of biperiden 2 or 4 mg, or placebo. Episodic memory was measured using a 15-word verbal learning task (VLT). Furthermore, n-back tasks, a sustained attention to response task and a reaction time task were used, as well as subjective alertness and a side effects questionnaire. In addition, blood serum values and physiological measures were taken.

FINDINGS/RESULTS

Biperiden decreased the number of words recalled in immediate and delayed recall of the VLT 90 minutes after drug intake. A dose-dependent impairment was found for the delayed recall, whereas the immediate recall was equally impaired by the 2 doses. Biperiden did not affect the performance on the VLT 4 hours after administration. Performance in the n-back task and the sustained attention to response task were not affected by biperiden at any time point. Both doses were well tolerated as reported side effects were mild at Tmax and were minimal at the other time points.

IMPLICATIONS/CONCLUSIONS

Biperiden exerts effects on episodic memory without negatively affecting other cognitive performance and behavioral measures that were assessed in this study. The data provide further evidence that biperiden has selective effects on cognition, even after a high dose.

Comparison of the muscarinic antagonist effects of scopolamine and L-687,306

This study aimed to use central and peripheral assays to compare the effects of the muscarinic antagonist scopolamine with those of a novel muscarinic antagonist, L-687,306 [(3R,4R)-3-(3-cyclopropyl-1,2,4,oxadiazol[5-yl]-1-azabicyclo[2.2.1]heptane. Groups of rats were trained to discriminate the stimulus effects of the muscarinic agonist, arecoline (1.0 mg/kg); concomitant measures of response rate were recorded. Separate groups were prepared with telemetery devices for recording bradycardia induced by arecoline (10 mg/kg). Methyl arecoline and arecoline were nearly equally potent in producing a brief but profound bradycardia, indicative of an equivalent effect in the heart. L-687,306 and scopolamine were both able to block this peripheral effect of arecoline. L-687,306 produced a surmountable antagonism of both the discriminative and rate-suppressing effects of arecoline. Scopolamine, however, was unable to antagonize the rate-reducing effects of arecoline in the discrimination assay. This limited the number of rats that could respond to the discriminative stimulus effects of arecoline, as well as the amount of arecoline stimulus effects they were able to report. The data suggest that L-687,306 may be a more generally effective muscarinic antagonist than scopolamine and support earlier reports that this antagonist has less direct effect on behavior.

Fat-1 expression enhance hippocampal memory in scopolamine-induced amnesia

Omega-3 polyunsaturated fatty acids (PUFA) are critical for optimal brain health and are involved in psychiatric and neurological ailments. Here, we report the effects of higher endogenous omega-3 PUFA on memory impairment in the hippocampus by studying mice with transgenic expression of the fat-1 gene that converts omega-6 to omega-3 PUFA. We performed Y-maze and passive avoidance tests to evaluate the memory function of fat-1 mice treated with scopolamine. Fat-1 mice showed induced alternation in the Y-maze test and increased latency in the passive avoidance test. The effects of scopolamine on hippocampal neurogenesis were confirmed by increases in the number of Ki-67- and DCX-positive cells in the fat-1 mice. Western blotting revealed increased brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element-binding protein levels, and lower scopolamine-induced apoptosis based on the cleaved-caspase 3 protein level in fat-1 mice. These findings suggest that higher endogenous omega-3 PUFA prevented granular cell loss, increased BDNF signaling, and decreased apoptosis signaling in scopolamine-treated fat-1 mice. These processes may underlie granular cell survival and suggest potential therapeutic targets for memory impairment.

Multitarget Activities of Kleeb Bua Daeng, a Thai Traditional Herbal Formula, Against Alzheimer's Disease

The Kleeb Bua Daeng formula (KBD) is a Thai traditional medicine for brain health promotion. On the basis of the activities of its individual components, the KBD could have good potential for the treatment of Alzheimer’s disease (AD). Herein, we investigated the KBD as an AD treatment. The ethanol extracts of KBD and its components, i.e., Nelumbo nucifera (NN), Piper nigrum fruits (BP), and the aerial part of Centella asiatica (CA) exhibited antioxidant activity, as determined by both ABTS and DPPH assays. The Ellman’s assay revealed that the KBD, NN, and BP showed an ability to inhibit acetylcholinesterase. The thioflavin T assay indicated that the KBD, NN, BP, and CA inhibited beta-amyloid aggregation. The neuroprotection and Western blot analysis revealed that the KBD reduced H₂O₂-induced neuronal cell death by inhibiting the expression of pro-apoptotic factors, i.e., cleaved caspase-9 and -3, p-P65, p-JNK, and p-GSK-3β, as well as by inducing expression of anti-apoptotic factors, i.e., MCl₁, BCl_xl, and survivin. Furthermore, the KBD could improve scopolamine induced memory deficit in mice. Our results illustrate that the KBD with multimode action has the potential to be employed in AD treatment. Thus, the KBD could be used as an alternative novel choice for the prevention and treatment of patients with AD.

Walnut Oil Prevents Scopolamine-Induced Memory Dysfunction in a Mouse Model

For thousands of years, it has been widely believed that walnut is a kind of nut that has benefits for the human body. Walnut oil, accounting for about 70% of walnut, mainly consists of polyunsaturated fatty acids. To investigate the effect of walnut oil on memory impairment in mice, scopolamine (3 mg/kg body weight/d) was used to establish the animal model during Morris Water Maze (MWM) tests. Walnut oil was administrated orally at 10 mL/kg body weight/d for 8 consecutive weeks. The results showed that walnut oil treatment ameliorated the behavior of the memory-impaired mice in the MWM test. Additionally, walnut oil obviously inhibited acetylcholinesterase activity (1.26 ± 0.12 U/mg prot) (p = 0.013) and increased choline acetyltransferase activity (129.75 ± 6.76 U/mg tissue wet weight) in the brains of scopolamine-treated mice (p = 0.024), suggesting that walnut oil could prevent cholinergic function damage in mice brains. Furthermore, walnut oil remarkably prevented the decrease in total superoxide dismutase activity (93.30 ± 5.50 U/mg prot) (p = 0.006) and glutathione content (110.45 ± 17.70 mg/g prot) (p = 0.047) and the increase of malondialdehyde content (13.79 ± 0.96 nmol/mg prot) (p = 0.001) in the brain of scopolamine-treated mice, indicating that walnut oil could inhibit oxidative stress in the brain of mice. Furthermore, walnut oil prevented histological changes of neurons in hippocampal CA1 and CA3 regions induced by scopolamine. These findings indicate that walnut oil could prevent memory impairment in mice, which might be a potential way for the prevention of memory dysfunctions.

D-ribose-L-cysteine enhances memory task, attenuates oxidative stress and acetyl-cholinesterase activity in scopolamine amnesic mice

d-Ribose-l-cysteine (DRLC) is an analogue of cysteine that has been shown to boost cellular antioxidant capacity by enhancing intracellular biosynthesis of glutathione (GSH). Deficiency of GSH has been implicated in the pathogenesis of Alzheimer's disease (AD), a neurodegenerative disorder associated with loss of memory. Thus, the use of antioxidants to prevent or retard the progression of memory deteriorations in persons with AD has been the focus of intense investigations. This study was carried out to evaluate the effects of DRLC on memory and scopolamine-induced amnesia, acetyl-cholinesterase activity, and oxidative stress in mice. Male Swiss mice were given oral administration of saline (10 ml/kg), DRLC (25, 50, and 100 mg/kg) or donepezil (1 mg/kg) 30 min before testing for memory performance using Y-maze and object recognition models. Another set of mice were also pretreated orally with saline, DRLC (25, 50, and 100 mg/kg) or donepezil (1 mg/kg) but in combination with scopolamine (3 mg/kg, i.p.) daily for 7 days. Thirty minutes after treatment on Day 7, memory function was then evaluated. The brain levels of acetyl-cholinesterase and oxidative stress parameters were assayed. DRLC significantly (p < .05) enhanced memory performance and attenuated scopolamine-induced amnesia. Increased acetyl-cholinesterase activity and oxidative stress, as shown by decreased antioxidant substrates (glutathione and catalase) and elevated malondialdehyde contents in mice with scopolamine amnesia were also attenuated by DRLC. Our findings suggest that inhibition of oxidative stress and acetyl-cholinesterase activity might contribute to the potential benefit of DRLC in persons with amnesia.

In Vivo Cognitive-Enhancing, Ex Vivo Malondialdehyde-Lowering Activities and Phytochemical Profiles of Aqueous and Methanolic Stem Bark Extracts of Piliostigma thonningii (Schum.)

Cognitive impairment (CI) is among the leading causes of disability in humans. It is estimated that over 35.6 million people are suffering from Alzheimer's disease- (AD-) associated cognitive deficits globally with these statistics projected to rise over 115.4 million by the year 2050. There is no specific etiology for this cognitive impairment; however, various contributing factors including advancing age (>60 years old), oxidative stress, cerebral injuries, infections, neurologic disorders, and cancer have been implicated. Despite various attempts to manage CI, no curative medicines are yet available. The current drugs used to manage symptoms of AD-associated CI including Donepezil and Rivastigmine among others are only palliative rather than therapeutic. Furthermore, these agents have been associated with undesirable side effects. This calls for alternative and complementary approaches aimed at either preventing or reverting AD-related CI in a curative way without causing adverse events. It is estimated that over 80% of the world's population utilize herbal medicines for basic healthcare as it is considered safe, affordable, and easily accessible as opposed to conventional healthcare. Various parts of P. thonningii are used in traditional medicine to manage various conditions including CI. However, empirical and scientific data to validate these uses is lacking. In this study, the Morris water maze (MWM) experiment was adopted to evaluate the cognitive-enhancing effects of the studied plant extracts. The malondialdehyde (MDA) profiles in the brains of experimental mice were determined using the thiobarbituric acid reactive substances (TBARS) test. Moreover, qualitative phytochemical profiling of the studied plant extracts was performed using standard procedures. The results showed remarkable cognitive-enhancing activities which were reflected in significantly shorter transfer latencies, navigation distances, longer time spent in platform quadrant, and lower MDA levels compared with those recorded for the negative control mice (p < 0.05). Phytochemical screening of the studied plant extracts revealed the presence of antioxidant phytocompounds, which may have played key roles in the extracts' potency. Based on the findings herein, P. thonningii extracts, especially the aqueous ones have a promising potential for the management of AD-associated CI. Further studies aimed at isolating and characterizing specific active compounds for CI from P. thonningii are recommended. Additionally, specific mode(s) of action of active principles should be elucidated. Moreover, toxicity studies should be done on the studied plant extracts to ascertain their safety.

A randomised, double-blind, active placebo-controlled, parallel groups, dose-response study of scopolamine hydrobromide (4-6 μg/kg) in patients with major depressive disorder

Background

Depressive disorders are a leading cause of disability, but current behavioural and pharmacological therapies have a slow onset of response, typically taking several weeks before achieving efficacy. Prior studies using triplicate intravenous scopolamine infusions have been shown to reduce depressive symptomologies within days compared to saline placebo infusions. However, several parameters of scopolamine’s potential antidepressant effect remain unknown, such as its dose–response profile and its washout period. There is also the question as to whether the previously reported antidepressant responses were confounded by unblinding effects due to the lack of an active placebo control. Glycopyrronium bromide was selected as placebo for this trial given it has similar antimuscarinic properties to scopolamine hydrobromide but an inability to cross the blood–brain barrier, thereby hypothetically mimicking only the peripheral effects of scopolamine.

Methods/Design

A parallel group trial of single intravenous scopolamine infusions at three doses (4, 5, and 6 μg/kg) along with one glycopyrronium bromide 4 μg/kg group will be administered to 40 participants with major depressive disorder in a 1:1:1:2 ratio, respectively. The primary outcome measure will be the Montgomery–Åsberg Depression Rating Scale (MADRS) administered at baseline, 4 hours, 1 day, 3 days, 1 week, 2 weeks, 4 weeks, and 6 weeks post-infusion to determine antidepressant efficacy. As a secondary measure, the Quick Inventory of Depressive Symptomatology will be administered alongside the MADRS to further track potential antidepressant responses. Other secondary measures include electroencephalography, blood samples, and Bowdle visual acuity scales recorded at baseline, 5, 10, 15, 20, 30, 60, 120, and 240 min post-infusion to determine the pharmacokinetic-pharmacodynamic profile of scopolamine in depressed participants.

Discussion

This trial contributes to the literature surrounding the efficacy of scopolamine as an antidepressant. Determining the dose–response profile and washout period of scopolamine’s antidepressant effect will also provide important information for designing and conducting crossover trials. The use of an active placebo is important to reduce potentially confounding expectancy effects.

Trial registration

The trial was registered in the Australian New Zealand Clinical Trials Registry (registration number ACTRN12619000569101). Registered on 11 April 2019.

Oral administration of hydrolyzed red ginseng extract improves learning and memory capability of scopolamine-treated C57BL/6J mice via upregulation of Nrf2-mediated antioxidant mechanism

Background

Korean ginseng (Panax ginseng Meyer) contains a variety of ginsenosides that can be metabolized to a biologically active substance, compound K. Previous research showed that compound K could be enriched in the red ginseng extract (RGE) after hydrolysis by pectinase. The current study investigated whether the enzymatically hydrolyzed red ginseng extract (HRGE) containing a notable level of compound K has cognitive improving and neuroprotective effects.

Methods

A scopolamine-induced hypomnesic mouse model was subjected to behavioral tasks, such as the Y-maze, passive avoidance, and the Morris water maze tests. After sacrificing the mice, the brains were collected, histologically examined (hematoxylin and eosin staining), and the expressions of antioxidant proteins analyzed by western blot.

Results

Behavioral assessment indicated that the oral administration of HRGE at a dosage of 300 mg/kg body weight reversed scopolamine-induced learning and memory deficits. Histological examination demonstrated that the hippocampal damage observed in scopolamine-treated mouse brains was reduced by HRGE administration. In addition, HRGE administration increased the expression of nuclear-factor-E2-related factor 2 and its downstream antioxidant enzymes NAD(P)H:quinone oxidoreductase and heme oxygenase-1 in hippocampal tissue homogenates. An in vitro assay using HT22 mouse hippocampal neuronal cells demonstrated that HRGE treatment attenuated glutamate-induced cytotoxicity by decreasing the intracellular levels of reactive oxygen species.

Conclusion

These findings suggest that HRGE administration can effectively alleviate hippocampus-mediated cognitive impairment, possibly through cytoprotective mechanisms, preventing oxidative-stress-induced neuronal cell death via the upregulation of phase 2 antioxidant molecules.