Neurocognitive effects of proanthocyanidin in Alzheimer's disease: a systematic review of preclinical evidence

Cognitive disorders and dementia largely influence individual independence and orientation. Based on the Alzheimer's Disease International (ADI) estimation, approximately 75% of individuals with dementia are undiagnosed. In fact, in some low- and middle-income countries, the percentage is as high as 90%. In this systematic review, which is based on PRISMA guidelines, we aim to identify the mechanism of action of proanthocyanidin. Finding a natural product alternative as a potential nootropic can help increase the number of armamentariums against dementia and other cognitive impairments. In this preclinical research, we determined the effect of proanthocyanidins on Alzheimer's disease (AD) by searching electronic bibliographic databases like Scopus, Proquest, ScienceDirect, PubMed, and Google. There was no imposed time limit. However, the search was limited to only English articles. The review protocol is registered on PROSPERO as CRD42022356301. A population, intervention, control, and outcomes (PICO) technique was utilized for report inclusion, and all reports were assessed for risk of bias by using the SYRCLE's RoB tool. The article's bibliographic information, induction model, type of proanthocyanidins, animal strain/weight/age, and outcome measurements were acquired from ten papers and are reported here. Further analysis was validated and determined for the review. The included studies met the review's inclusion criteria and suggested that proanthocyanidins have a neurocognitive effect against AD. Additionally, the effectiveness of proanthocyanidins in reducing oxidative stress, acetylcholinesterase activity, amyloid beta, its efficacy in alleviating superoxide dismutase, cognitive properties, and in facilitating cholinergic transmission in various models of AD has been collectively observed in ten studies.

A Mouse Model of Sporadic Alzheimer's Disease with Elements of Major Depression

After olfactory bulbectomy, animals are often used as a model of major depression or sporadic Alzheimer's disease and, hence, the status of this model is still disputable. To elucidate the nature of alterations in the expression of the genome after the operation, we analyzed transcriptomes of the cortex, hippocampus, and cerebellum of the olfactory bulbectomized (OBX) mice. Analysis of the functional significance of genes in the brain of OBX mice indicates that the balance of the GABA/glutamatergic systems is disturbed with hyperactivation of the latter in the hippocampus, leading to the development of excitotoxicity and induction of apoptosis in the background of severe mitochondrial dysfunction and astrogliosis. On top of this, the synthesis of neurotrophic factors decreases leading to the disruption of the cytoskeleton of neurons, an increase in the level of intracellular calcium, and the activation of tau protein hyperphosphorylation. Moreover, the acetylcholinergic system is deficient in the background of the hyperactivation of acetylcholinesterase. Importantly, the activity of the dopaminergic, endorphin, and opiate systems in OBX mice decreases, leading to hormonal dysfunction. On the other hand, genes responsible for the regulation of circadian rhythms, cell migration, and innate immunity are activated in OBX animals. All this takes place in the background of a drastic downregulation of ribosomal protein genes in the brain. The obtained results indicate that OBX mice represent a model of Alzheimer's disease with elements of major depression.

Ndufs4 KO mice: A model to study comorbid mood disorders associated with mitochondrial dysfunction

The Ndufs4 knockout (KO) mouse is a validated and robust preclinical model of mitochondrial diseases (specifically Leigh syndrome), that displays a narrow window of relative phenotypical normality, despite its inherent mitochondrial complex I dysfunction and severe phenotype. Preclinical observations related to psychiatric comorbidities that arise in patients with mitochondrial diseases and indeed in Leigh syndrome are, however, yet to be investigated in this model. Strengthening this narrative is the fact that major depression and bipolar disorder are known to present with deficits in mitochondrial function. We therefore screened the behavioural profile of male and female Ndufs4 KO mice (relative to heterozygous; HET and wildtype; WT mice) between postnatal days 28 and 35 for locomotor, depressive- and anxiety-like alterations and linked it with selected brain biomarkers, viz. serotonin, kynurenine, and redox status in brain areas relevant to psychiatric pathologies (i.e., prefrontal cortex, hippocampus, and striatum). The Ndufs4 KO mice initially displayed depressive-like behaviour in the tail suspension test on PND31 but not on PND35 in the forced swim test. In the mirror box test, increased risk resilience was observed. Serotonin levels of KO mice, compared to HET controls, were increased on PND36, together with increased tryptophan to serotonin and kynurenine turnover. Kynurenine to kynurenic acid turnover was however decreased, while reduced versus oxidized glutathione ratio (GSH/GSSG) was increased. When considering the comorbid psychiatric traits of patients with mitochondrial disorders, this work elaborates on the neuropsychiatric profile of the Ndufs KO mouse. Secondly, despite locomotor differences, Ndufs4 KO mice present with a behavioural profile not unlike rodent models of bipolar disorder, namely variable mood states and risk-taking behaviour. The model may elucidate the bio-energetic mechanisms underlying mood disorders, especially in the presence of mitochondrial disease. Studies are however required to further validate the model's translational relevance.

Efforts Towards Repurposing of Antioxidant Drugs and Active Compounds for Multiple Sclerosis Control

Multiple Sclerosis (MS) is a degenerative disorder of the central nervous system (CNS) with complicated etiology that has not been clearly analyzed until nowadays. Apart from anti-inflammatory, immune modulatory and symptomatic treatments, which are the main tools towards MS control, antioxidant molecules may be of interest. Oxidative stress is a key condition implicated in the disease progression. Reactive species production is associated with immune cell activation in the brain as well as in the periphery, accounting for demyelinating and axonal disruptive processes. This review refers to research articles, of the last decade. It describes biological evaluation of antioxidant drugs, and molecules with pharmaceutical interest, which are not designed for MS treatment, however they seem to have potency against MS. Their antioxidant effect is accompanied, in most of the cases, by anti-inflammatory, immune-modulatory and neuroprotective properties. Compounds with such characteristics are expected to be beneficial in the treatment of MS, alone or as complementary therapy, improving some clinical and mechanistic aspects of the disease. This review also summarizes some of the pathobiological characteristics of MS, as well as the role of oxidative stress and inflammation in the progression of neurodegeneration. It presents known drugs and bioactive compounds with antioxidant, and in many cases, pleiotropic activity that have been tested for their efficacy in MS progression or the experimentally induced MS. Antioxidants may offer reduction or prevention of the disease symptoms and progression. Thus, their results may, combined with already applied treatments, be beneficial for the development of new molecules or the repurposing of drugs and supplements that are used with other indication so far.

Optical Redox Imaging of Ex Vivo Hippocampal Tissue Reveals Age-Dependent Alterations in the 5XFAD Mouse Model of Alzheimer’s Disease

A substantial decline in nicotinamide adenine dinucleotide (NAD) has been reported in brain tissue homogenates or neurons isolated from Alzheimer’s disease (AD) models. NAD, together with flavin adenine dinucleotide (FAD), critically supports energy metabolism and maintains mitochondrial redox homeostasis. Optical redox imaging (ORI) of the intrinsic fluorescence of reduced NAD (NADH) and oxidized FAD yields cellular redox and metabolic information and provides biomarkers for a variety of pathological conditions. However, its utility in AD has not been characterized at the tissue level. We performed ex vivo ORI of freshly dissected hippocampi from a well-characterized AD mouse model with five familial Alzheimer’s disease mutations (5XFAD) and wild type (WT) control littermates at various ages. We found (1) a significant increase in the redox ratio with age in the hippocampi of both the WT control and the 5XFAD model, with a more prominent redox shift in the AD hippocampi; (2) a higher NADH in the 5XFAD versus WT hippocampi at the pre-symptomatic age of 2 months; and (3) a negative correlation between NADH and Aβ₄₂ level, a positive correlation between Fp and Aβ₄₂ level, and a positive correlation between redox ratio and Aβ₄₂ level in the AD hippocampi. These findings suggest that the ORI can be further optimized to conveniently study the metabolism of freshly dissected brain tissues in animal models and identify early AD biomarkers.

Ursolic acid and its isomer oleanolic acid are responsible for the anti-dementia effects of Ocimum sanctum in olfactory bulbectomized mice

This study aims to clarify the bioactive constituents responsible for the anti-dementia effects of Ocimum sanctum Linn. ethanolic extract (OS) using olfactory bulbectomized (OBX) mice, an animal model of dementia. The effects of OS or its extract further fractionated with n-hexane (OS-H), ethyl acetate (OS-E), and n-butanol (OS-B) on the spatial cognitive deficits of OBX mice were elucidated by the modified Y-maze tests. The effects of the major constituents of the most active OS fraction were also elucidated using the reference drug donepezil. The administration of OS and OS-E ameliorated the spatial cognitive deficits caused by OBX, whereas OS-H or OS-B had no effect. Two major constituents, ursolic acid (URO) and oleanolic acid (OLE), and three minor constituents were isolated from OS-E. URO (6 and 12 mg/kg) and OLE (24 mg/kg) attenuated the OBX-induced cognitive deficits. URO (6 mg/kg) and donepezil reversed the OBX-induced down-regulation of vascular endothelial growth factor (VEGF) and choline acetyltransferase expression levels in the hippocampus. URO inhibited the ex vivo activity of acetylcholinesterase with similar efficacy to donepezil. URO inhibited the in vitro activity of acetylcholinesterase (IC50 = 106.5 μM), while the effects of OS, OS-E, and other isolated compounds were negligible. These findings suggest that URO and OLE are responsible for the anti-dementia action of OS extract, whereas URO possesses a more potent anti-dementia effect than its isomer OLE. The effects of URO are, at least in part, mediated by normalizing the function of central cholinergic systems and VEGF protein expression.

Intranasal administration of mitochondria improves spatial memory in olfactory bulbectomized mice

Here, we found that functionally active mitochondria isolated from the brain of NMRI donor mice and administrated intranasally to recipient mice penetrated the brain structures in a dose-dependent manner. The injected mitochondria labeled with the MitoTracker Red localized in different brain regions, including the neocortex and hippocampus, which are responsible for memory and affected by degeneration in patients with Alzheimer's disease. In behavioral experiments, intranasal microinjections of brain mitochondria of native NMRI mice improved spatial memory in the olfactory bulbectomized (OBX) mice with Alzheimer's type degeneration. Control OBX mice demonstrated loss of spatial memory tested in the Morris water maze. Immunocytochemical analysis revealed that allogeneic mitochondria colocalized with the markers of astrocytes and neurons in hippocampal cell culture. The results suggest that a non-invasive route intranasal administration of mitochondria may be a promising approach to the treatment of neurodegenerative diseases characterized, like Alzheimer's disease, by mitochondrial dysfunction.

Systematic review and meta-analysis on the role of mitochondrial cytochrome c oxidase in Alzheimer's disease

OBJECTIVE

The present study was designed to test the hypothesis that there is a reduction in the activity of the enzyme cytochrome c oxidase (Cox) in Alzheimer's disease (AD).

METHODS

Systematic review of literature and meta-analysis were used with data obtained from the PubMed, Scopus, MEDLINE, Lilacs, Eric and Cochrane. The keywords were Alzheimer's AND Cox AND mitochondria; Alzheimer's AND Cox AND mitochondria; Alzheimer's AND complex IV AND mitochondria. A total of 1372 articles were found, 23 of them fitting the inclusion criteria. The data were assembled in an Excel spreadsheet and analysed using the RevMan software. A random effects model was adopted to the estimative of the effect.

RESULTS

The data shows a significant decrease in the activity of the Cox AD patients and animal models.

CONCLUSION

Cox enzyme may be an important molecular component involved in the mechanisms underlying AD. Therefore, this enzyme may represent a possible new biomarker for the disease as a complementary diagnosis and a new treatment target for AD.

Synthetic fragment (60-76) of RAGE improves brain mitochondria function in olfactory bulbectomized mice

The receptor for advanced glycation end products (RAGE) is considered to contribute to the pathogenesis of Alzheimer's disease (AD), mediating amyloid beta (Aβ) accumulation, mitochondrial damage, and neuroinflammation. Previously, we have synthesized small peptides corresponding to the fragments (60-76) (P1) and (60-62) (P2) of the RAGE extracellular domain, and have shown that administration of P1 fragment but not P2 results in restoration of the spatial memory and decreases the brain Aβ (1-40) level in olfactory bulbectomized (OBX) mice demonstrating main features of Alzheimer's type neurodegeneration. In the present study, we have investigated the supposed mechanism of the therapeutic efficacy of P1 RAGE fragment and compared it to P2 short fragment. We have found that P1 restored activities of the respiratory chain in the Complexes I and IV in both cortical and hippocampal mitochondria of the OBX mice while P2 had no effect. Besides, fluorescein-labeled analog Flu-P1 bound to Aβ (1-40) and Aβ (1-42) with high affinity (K_d in the nanomolar range) whereas Flu-P2 revealed low affinity with tenfold higher K_d value for Aβ (1-40) and did not bind to Aβ (1-42). However, neither of the peptides had a notable impact on inflammation, estimated as mRNA expression of proinflammatory cytokines in the brain tissues of OBX mice. Taken together, our results suggest that direct Aβ-P1 interaction is one of the molecular events mediating the protection of the mitochondria in OBX animals from Aβ toxic effect. The RAGE fragment P1 would be the soluble decoy for Aβs and serve as a promising therapeutic agent against neurodegeneration accompanied by mitochondrial dysfunction.

Analyses of Clinical Features and Investigations on Potential Mechanisms in Patients with Alzheimer's Disease and Olfactory Dysfunction

BACKGROUND

OD is common in patients with Alzheimer's disease (AD). However, the relationship between OD and clinical symptoms and the potential mechanisms of OD in AD patients are still unknown.

OBJECTIVE

To explore the relationship between OD and clinical symptoms and the potential mechanisms of OD in AD patients.

METHODS

We evaluated OD using the Hyposmia Rating Scale (HRS), classified patients into AD with OD (AD-OD) and AD with no OD (AD-NOD) groups, and detected the levels of free radicals and inflammatory factors, including hydroxyl radical (•OH), hydrogen peroxide (H2O2), nitric oxide, interleukin-1β, interleukin-6, tumor necrosis factor-α, and prostaglandin E2 in serum from AD patients.

RESULTS

It was shown that the scores of the Mini-Mental State Examination, Animal Fluency Test, Boston Naming Test (BNT), and Auditory Verbal Learning Test-delayed recall were all significantly lower and the score of overall activity of daily living (ADL) and instrumental ADL were significantly higher in AD-OD group than those in AD-NOD group. Compared with AD-NOD group, •OH level in serum was prominently elevated, and H2O2 level was dramatically declined in AD-OD group. In the correlation analysis, HRS score was significantly and positively correlated with the score of BNT, and negatively correlated with •OH level in serum.

CONCLUSIONS

AD-OD patients suffered from severe cognitive impairment in the domain of language. Oxidative stress might be correlated with AD-OD featured by the drastically increased •OH level in serum.

Therapeutic Effect of the Mitochondria-Targeted Antioxidant SkQ1 on the Culture Model of Multiple Sclerosis

Multiple sclerosis (MS) is a heterogeneous autoimmune disease of unknown etiology characterized by inflammation, demyelination, and axonal degeneration that affects both the white and gray matter of CNS. Recent large-scale epidemiological and genomic studies identified several genetic and environmental risk factors for the disease. Among them are environmental factors of infectious origin, possibly causing MS, which include Epstein-Barr virus infection, reactivation of some endogenous retrovirus groups, and infection by pathogenic bacteria (mycobacteria, Chlamydia pneumoniae, and Helicobacter pylori). However, the nature of the events leading to the activation of immune cells in MS is mostly unknown and there is no effective therapy against the disease. Amazingly, whatever the cause of the disease, signs of damage to the nerve tissue with MS lesions were the same as with infectious leprosy, while in the latter case nitrozooxidative stress was suggested as the main cause of the nerve damage. With this in mind and following the hypothesis that excessive production of mitochondrial reactive oxygen species critically contributes to MS pathogenesis, we studied the effect of mitochondria-targeted antioxidant SkQ1 in an in vitro MS model of the primary oligodendrocyte culture of the cerebellum, challenged with lipopolysaccharide (LPS). SkQ1 was found to accumulate in the mitochondria of oligodendrocytes and microglial cells, and it was also found to prevent LPS-induced inhibition of myelin production in oligodendrocytes. The results implicate that mitochondria-targeted antioxidants could be promising candidates as components of a combined therapy for MS and related neurological disorders.

The role of mitochondrial defects and oxidative stress in Alzheimer's disease

Alzheimer's disease (AD) is a complex, progressive, and irreversible neurodegenerative disorder. Recent reports suggest that it affects more than 36 million people worldwide and accounts 60-80% of all cases of dementia. It is characterised by aberrations of multiple interactive systems and pathways, which ultimately lead to memory loss and cognitive dysfunction. The exact mechanisms and initial triggering factors that underpin the known pathological defects in AD remain to be fully elucidated. In addition, an effective treatment strategy to reduce the progression of AD is yet to be achieved. In the light of above-mentioned facts, our article deals with the exploration of the mitochondrial defect and oxidative stress leading to this devastating disease. In this communication, we have highlighted specific mitochondrial and antioxidant-directed approach to ameliorate and manage AD. Nonetheless, new approaches should also be investigated that could tackle various molecular events involved in AD pathogenicity.

The Impact of ESCRT on Aβ1-42 Induced Membrane Lesions in a Yeast Model for Alzheimer's Disease

Aβ metabolism plays a pivotal role in Alzheimer’s disease. Here, we used a yeast model to monitor Aβ₄₂ toxicity when entering the secretory pathway and demonstrate that processing in, and exit from the endoplasmic reticulum (ER) is required to unleash the full Aβ₄₂ toxic potential. Consistent with previously reported data, our data suggests that Aβ₄₂ interacts with mitochondria, thereby enhancing formation of reactive oxygen species and eventually leading to cell demise. We used our model to search for genes that modulate this deleterious effect, either by reducing or enhancing Aβ₄₂ toxicity, based on screening of the yeast knockout collection. This revealed a reduced Aβ₄₂ toxicity not only in strains hampered in ER-Golgi traffic and mitochondrial functioning but also in strains lacking genes connected to the cell cycle and the DNA replication stress response. On the other hand, increased Aβ₄₂ toxicity was observed in strains affected in the actin cytoskeleton organization, endocytosis and the formation of multivesicular bodies, including key factors of the ESCRT machinery. Since the latter was shown to be required for the repair of membrane lesions in mammalian systems, we studied this aspect in more detail in our yeast model. Our data demonstrated that Aβ₄₂ heavily disturbed the plasma membrane integrity in a strain lacking the ESCRT-III accessory factor Bro1, a phenotype that came along with a severe growth defect and enhanced loading of lipid droplets. Thus, it appears that also in yeast ESCRT is required for membrane repair, thereby counteracting one of the deleterious effects induced by the expression of Aβ₄₂. Combined, our studies once more validated the use of yeast as a model to investigate fundamental mechanisms underlying the etiology of neurodegenerative disorders.

Involvement of Mitochondria in Neurodegeneration in Multiple Sclerosis

Functional disruption and neuronal loss followed by progressive dysfunction of the nervous system underlies the pathogenesis of numerous disorders defined as "neurodegenerative diseases". Multiple sclerosis, a chronic inflammatory demyelinating disease of the central nervous system resulting in serious neurological dysfunctions and disability, is one of the most common neurodegenerative diseases. Recent studies suggest that disturbances in mitochondrial functioning are key factors leading to neurodegeneration. In this review, we consider data on mitochondrial dysfunctions in multiple sclerosis, which were obtained both with patients and with animal models. The contemporary data indicate that the axonal degeneration in multiple sclerosis largely results from the activation of Ca2+-dependent proteases and from misbalance of ion homeostasis caused by energy deficiency. The genetic studies analyzing association of mitochondrial DNA polymorphic variants in multiple sclerosis suggest the participation of mitochondrial genome variability in the development of this disease, although questions of the involvement of individual genomic variants are far from being resolved.

Effect of weak combined static and extremely low-frequency alternating magnetic fields on spatial memory and brain amyloid-β in two animal models of Alzheimer's disease

Subchronic effect of a weak combined magnetic field (MF), produced by superimposing a constant component, 42 µT and an alternating MF of 0.08 µT, which was the sum of two frequencies of 4.38 and 4.88 Hz, was studied in olfactory bulbectomized (OBE) and transgenic Tg (APPswe, PSEN1) mice, which were used as animal models of sporadic and heritable Alzheimer's disease (AD) accordingly. Spatial memory was tested in a Morris water maze on the following day after completion of training trials with the hidden platform removed. The amyloid-β (Aβ) level was determined in extracts of the cortex and hippocampus of mice using a specific DOT analysis while the number and dimensions of amyloid plaques were detected after their staining with thioflavin S in transgenic animals. Exposure to the MFs (4 h/day for 10 days) induced the decrease of Aβ level in brain of OBE mice and reduced the number of Aβ plaques in the cortex and hippocampus of Tg animals. However, memory improvement was revealed in Tg mice only, but not in the OBE animals. Here, we suggest that in order to prevent the Aβ accumulation, MFs could be used at early stage of neuronal degeneration in case of AD and other diseases with amyloid protein deposition in other tissues.

Role of mitochondrial ROS in the brain: from physiology to neurodegeneration

Mitochondria are key cell organelles in that they are responsible for energy production and control many processes from signalling to cell death. The function of the mitochondrial electron transport chain is coupled with the production of reactive oxygen species (ROS) in the form of superoxide anion or hydrogen peroxide. As a result of the constant production of ROS, mitochondria are protected by highly efficient antioxidant systems. The rapidly changing levels of ROS in mitochondria, coupled with multiple essential cellular functions, make ROS apt for physiological signalling. Thus, mutations, environmental toxins and chronic ischaemic conditions could affect the mitochondrial redox balance and lead to the development of pathology. In long-living and non-mitotic cells such as neurons, oxidative stress induced by overproduction of mitochondrial ROS or impairment of the antioxidant defence results in a dysfunction of mitochondria and initiation of the cell death cascade. Mitochondrial ROS overproduction and changes in mitochondrial redox homeostasis have been shown to be involved in both a number of neurological conditions and a majority of neurodegenerative diseases. Here, we summarise the involvement of mitochondrial ROS in the mechanism of neuronal loss of major neurodegenerative disorders.

Multi-Protection of DL0410 in Ameliorating Cognitive Defects in D-Galactose Induced Aging Mice

D-galactose has been reported to accelerate senescence in rodents, accompanied by a decline in learning and memory. We used a model of D-galactose-induced amnesia for the efficacy evaluation and pharmacologic studies of active compounds against Alzheimer's disease (AD). DL0410 is a potent inhibitor against acetylcholinesterase (AChE) and, in the present study, the effect of DL0410 was evaluated in this model. We found that DL0410 could significantly improve the learning and memory of D-galactose induced aging mice in a series of behavioral tests: novel-object recognition test, nest-building test, Morris water maze test and step-through test. Pharmacologic studies were conducted from several aspects: the cholinergic system, mitochondrial respiration, oxidative stress, neuroinflammation, apoptosis and synaptic loss. The acetylcholine level and AChE activity were not altered by D-galactose but were slightly affected by DL0410 in the brain. DL0410 could significantly improve decreased mitochondrial respiration in the NADH chain and FADH2 chain, and protect mitochondrial ultrastructure. DL0410 reduced the accumulation of advanced glycation end products (AGEs) and malondialdehyde (MDA) and increase the total antioxidant capability of the brain via an increase in activity of catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). RAGE expression was inhibited by DL0410, followed by the decreased activation of astrocytes and microglia. Subsequent phosphorylation of NF-κB was also reversed by DL0410, with lower expression of cyclooxygenase-2 (COX2) and iNOS. With respect to apoptosis, the activation of caspase 3 and cleavage of PARP were downregulated significantly by DL0410, after the inhibition of phosphorylation of JNK induced by inflammation and oxidative stress. Synaptic protection by DL0410 was also demonstrated. These data suggest that mitochondrial protection has a primary role in the ameliorating effect of DL0410 on the impaired learning and memory, oxidative stress, inflammation, apoptosis and synaptic loss induced by D-galactose. DL0410 is a promising candidate for the treatment of aging-related AD, and this study lays an important foundation for its further research and development.

Molecular and Cellular Mechanisms of Sporadic Alzheimer's Disease: Studies on Rodent Models in vivo

In this review, recent data are presented on molecular and cellular mechanisms of pathogenesis of the most widespread (about 95%) sporadic forms of Alzheimer's disease obtained on in vivo rodent models. Although none of the available models can fully reproduce the human disease, several key molecular mechanisms (such as dysfunction of neurotransmitter systems, especially of the acetylcholinergic system, β-amyloid toxicity, oxidative stress, neuroinflammation, mitochondrial dysfunction, disturbances in neurotrophic systems) are confirmed with different models. Injection models, olfactory bulbectomy, and senescence accelerated OXYS rats are reviewed in detail. These three approaches to in vivo modeling of sporadic Alzheimer's disease have demonstrated a considerable similarity in molecular and cellular mechanisms of pathology development. Studies on these models provide complementary data, and each model possesses its specific advantages. A general analysis of the data reported for the three models provides a multifaceted and the currently most complete molecular picture of sporadic Alzheimer's disease. This is highly relevant also from the practical viewpoint because it creates a basis for elaboration and preclinical studies of means for treatment of this disease.

Cognitive behavioral therapy (CBT) for preventing Alzheimer's disease

This review provides the rationale for implementing cognitive behavioral therapy (CBT) for the prevention of Alzheimer's disease (AD). There are known risk factors associated with the development of AD, some of which may be ameliorated with CBT. We posit that treating the risk factors of inactivity, poor diet, hyposmia and anosmia, sleep disorders and lack of regularly engaged challenging cognitive activity will modify the physiology of the brain sufficiently to avoid the accumulation of excess proteins, including amyloid beta, causal events in the development of AD. Further, the successful treatment of the listed risk factors is well within our technology to do so and, even further, it is cost effective. Also, there is considerable scientific literature to support the proposition that, if implemented by well-established practices, CBT will be effective and will be engaged by those of retirement age. That is, we present a biologically informed CBT for the prevention of the development of AD, i.e., an aspect of applied behavioral neuroscience.

Pinocembrin Attenuates Mitochondrial Dysfunction in Human Neuroblastoma SH-SY5Y Cells Exposed to Methylglyoxal: Role for the Erk1/2-Nrf2 Signaling Pathway

Pinocembrin (PB; 5,7-dihydroxyflavanone) is found in propolis and exhibits antioxidant activity in several experimental models. The antioxidant capacity of PB is associated with the activation of the nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signaling pathway. The Nrf2/ARE axis mediates the expression of antioxidant and detoxifying enzymes, such as glutathione peroxidase (GPx), glutathione reductase (GR), heme oxygenase-1 (HO-1), and the catalytic (GCLC) and regulatory (GCLM) subunits of the rate-limiting enzyme in the synthesis of glutathione (GSH), γ-glutamate-cysteine ligase (γ-GCL). Nonetheless, it is not clear how PB exerts mitochondrial protection in mammalian cells. Human neuroblastoma SH-SY5Y cells were pretreated (4 h) with PB (0-25 µM) and then exposed to methylglyoxal (MG; 500 µM) for further 24 h. Mitochondria were isolated by differential centrifugation. PB (25 µM) provided mitochondrial protection (decreased lipid peroxidation, protein carbonylation, and protein nitration in mitochondrial membranes; decreased mitochondrial free radical production; enhanced the content of GSH in mitochondria; rescued mitochondrial membrane potential-MMP) and blocked MG-triggered cell death by a mechanism dependent on the activation of the extracellular-related kinase (Erk1/2) and consequent upregulation of Nrf2. PB increased the levels of GPx, GR, HO-1, and mitochondrial GSH. The PB-induced effects were suppressed by silencing of Nrf2 with siRNA. Therefore, PB activated the Erk1/2-Nrf2 signaling pathway resulting in mitochondrial protection in SH-SY5Y cells exposed to MG. Our work shows that PB is a strong candidate to figure among mitochondria-focusing agents with pharmacological potential.