Impairment of PGC-1α-mediated mitochondrial biogenesis precedes mitochondrial dysfunction and Alzheimer's pathology in the 3xTg mouse model of Alzheimer's disease

Effect of imipramine on memory, adult neurogenesis, neuroinflammation, and mitochondrial biogenesis in a rat model of alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline and memory loss. Imipramine, a tricyclic antidepressant, has potent anti-inflammatory and antioxidant properties in the central nervous system. The aim of this study was to investigate the neuroprotective effects of imipramine on streptozotocin (STZ)-induced memory impairment. Male Wistar rats received an intracerebroventricular injection of STZ (3 mg/kg, 3 μl/ventricle) using the stereotaxic apparatus. The Morris water maze and passive avoidance tests were used to evaluate cognitive functions. 24 h after the STZ injection, imipramine was administered intraperitoneally at doses of 10 or 20 mg/kg for 14 consecutive days. The mRNA and protein levels of neurotrophic factors (BDNF and GDNF) and pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) were measured in the hippocampus using real-time PCR and ELISA techniques, respectively. In addition, real-time PCR was used to evaluate the mRNA levels of markers associated with neurogenesis (Nestin, DCX, and Ki67) and mitochondrial biogenesis (PGC-1α, NRF-1, and TFAM). The results showed that imipramine, especially at a dose of 20 mg/kg, effectively improved STZ-induced memory impairment. This improvement was associated with an increase in neurogenesis and neurotrophic factors and a decrease in neuroinflammation and mitochondrial biogenesis dysfunction. Based on these results, imipramine appears to be a promising therapeutic option for improving cognitive functions in neurodegenerative diseases such as AD.

Neurodegeneration and glial morphological changes are both prevented by TRPM2 inhibition during the progression of a Parkinson's disease mouse model

Parkinson's disease (PD) is a neurodegenerative disease characterized by dopaminergic neuron death and neuroinflammation. Emerging evidence points to the involvement of the transient receptor potential melastatin 2 (TRPM2) channel in neuron death and glial activation in several neurodegenerative diseases. However, the involvement of TRPM2 in PD and specifically its relation to the neuroinflammation aspect of the disease remains poorly understood. Here, we hypothesized that AG490, a TRPM2 inhibitor, can be used as a treatment in a mouse model of PD. Mice underwent stereotaxic surgery for 6-hydroxydopamine (6-OHDA) administration in the right striatum. Motor behavioral tests (apomorphine, cylinder, and rotarod) were performed on day 3 post-injection to confirm the PD model induction. AG490 was then daily injected i.p. between days 3 to 6 after surgery. On day 6, motor behavior was assessed again. Substantia nigra (SNc) and striatum (CPu) were collected for immunohistochemistry, immunoblotting, and RT-qPCR analysis on day 7. Our results revealed that AG490 post-treatment reduced motor behavior impairment and nigrostriatal neurodegeneration. In addition, the compound prevented TRPM2 upregulation and changes of the Akt/GSK-3β/caspase-3 signaling pathway. The TRPM2 inhibition also avoids the glial morphology changes observed in the PD group. Remarkably, the morphometrical analysis revealed that the ameboid-shaped microglia, found in 6-OHDA-injected animals, were no longer present in the AG490-treated group. These results indicate that AG490 treatment can reduce dopaminergic neuronal death and suppress neuroinflammation in a PD mouse model. Inhibition of TRPM2 by AG490 could then represent a potential therapeutical strategy to be evaluated for PD treatment.

Se-methylselenocysteine ameliorates mitochondrial function by targeting both mitophagy and autophagy in the mouse model of Alzheimer's disease

Background: Alzheimer's disease (AD) exerts tremendous pressure on families and society due to its unknown etiology and lack of effective treatment options. Our previous study had shown that Se-methylselenocysteine (SMC) improved the cognition and synaptic plasticity of triple-transgenic AD (3 × Tg-AD) mice and alleviated the related pathological indicators. We are dedicated to investigating the therapeutic effects and molecular mechanisms of SMC on mitochondrial function in 3 × Tg-AD mice. Methods: Transmission electron microscopy (TEM), western blotting (WB), mitochondrial membrane potential (ΔΨm), mitochondrial swelling test, and mitochondrial oxygen consumption test were used to evaluate the mitochondrial morphology and function. Mitophagy flux and autophagy flux were assessed with immunofluorescence, TEM and WB. The Morris water maze test was applied to detect the behavioral ability of mice. Results: The destroyed mitochondrial morphology and function were repaired by SMC through ameliorating mitochondrial energy metabolism, mitochondrial biogenesis and mitochondrial fusion/fission balance in 3 × Tg-AD mice. In addition, SMC ameliorated mitochondria by activating mitophagy flux via the BNIP3/NIX pathway and triggering autophagy flux by suppressing the Ras/Raf/MEK/ERK/mTOR pathway. SMC remarkably increased the cognitive ability of AD mice. Conclusions: This research indicated that SMC might exert its therapeutic effect by protecting mitochondria in 3 × Tg-AD mice.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family in physiological and pathophysiological process and diseases

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family (PGC-1s), consisting of three members encompassing PGC-1α, PGC-1β, and PGC-1-related coactivator (PRC), was discovered more than a quarter-century ago. PGC-1s are essential coordinators of many vital cellular events, including mitochondrial functions, oxidative stress, endoplasmic reticulum homeostasis, and inflammation. Accumulating evidence has shown that PGC-1s are implicated in many diseases, such as cancers, cardiac diseases and cardiovascular diseases, neurological disorders, kidney diseases, motor system diseases, and metabolic disorders. Examining the upstream modulators and co-activated partners of PGC-1s and identifying critical biological events modulated by downstream effectors of PGC-1s contribute to the presentation of the elaborate network of PGC-1s. Furthermore, discussing the correlation between PGC-1s and diseases as well as summarizing the therapy targeting PGC-1s helps make individualized and precise intervention methods. In this review, we summarize basic knowledge regarding the PGC-1s family as well as the molecular regulatory network, discuss the physio-pathological roles of PGC-1s in human diseases, review the application of PGC-1s, including the diagnostic and prognostic value of PGC-1s and several therapies in pre-clinical studies, and suggest several directions for future investigations. This review presents the immense potential of targeting PGC-1s in the treatment of diseases and hopefully facilitates the promotion of PGC-1s as new therapeutic targets.

The Natural Alkaloid Palmatine Selectively Induces Mitophagy and Restores Mitochondrial Function in an Alzheimer's Disease Mouse Model

Palmatine, a natural alkaloid found in various plants, has been reported to have diverse pharmacological and biological effects, including anti-inflammatory, antioxidant, and cardiovascular effects. However, the role of palmatine in mitophagy, a fundamental process crucial for maintaining mitochondrial function, remains elusive. In this study, we found that palmatine efficiently induces mitophagy in various human cell lines. Palmatine specifically induces mitophagy and subsequently stimulates mitochondrial biogenesis. Palmatine did not interfere with mitochondrial function, similar to CCCP, suggesting that palmatine is not toxic to mitochondria. Importantly, palmatine treatment alleviated mitochondrial dysfunction in PINK1-knockout MEFs. Moreover, the administration of palmatine resulted in significant improvements in cognitive function and restored mitochondrial function in an Alzheimer's disease mouse model. This study identifies palmatine as a novel inducer of selective mitophagy. Our results suggest that palmatine-mediated mitophagy induction could be a potential strategy for Alzheimer's disease treatment and that natural alkaloids are potential sources of mitophagy inducers.

Mitochondria and Oxidative Stress as a Link between Alzheimer's Disease and Diabetes Mellitus

This review is devoted to the problems of the common features linking metabolic disorders and type 2 diabetes with the development of Alzheimer's disease. The pathogenesis of Alzheimer's disease closely intersects with the mechanisms of type 2 diabetes development, and an important risk factor for both pathologies is aging. Common pathological mechanisms include both factors in the development of oxidative stress, neuroinflammation, insulin resistance, and amyloidosis, as well as impaired mitochondrial dysfunctions and increasing cell death. The currently available drugs for the treatment of type 2 diabetes and Alzheimer's disease have limited therapeutic efficacy. It is important to note that drugs used to treat Alzheimer's disease, in particular acetylcholinesterase inhibitors, show a positive therapeutic potential in the treatment of type 2 diabetes, while drugs used in the treatment of type 2 diabetes can also prevent a number of pathologies characteristic for Alzheimer's disease. A promising direction in the search for a strategy for the treatment of type 2 diabetes and Alzheimer's disease may be the creation of complex multi-target drugs that have neuroprotective potential and affect specific common targets for type 2 diabetes and Alzheimer's disease.

Current Advances in Mitochondrial Targeted Interventions in Alzheimer's Disease

Alzheimer's disease is the most prevalent neurodegenerative disorder and affects the lives not only of those who are diagnosed but also of their caregivers. Despite the enormous social, economic and political burden, AD remains a disease without an effective treatment and with several failed attempts to modify the disease course. The fact that AD clinical diagnosis is most often performed at a stage at which the underlying pathological events are in an advanced and conceivably irremediable state strongly hampers treatment attempts. This raises the awareness of the need to identify and characterize the early brain changes in AD, in order to identify possible novel therapeutic targets to circumvent AD's cascade of events. One of the most auspicious targets is mitochondria, powerful organelles found in nearly all cells of the body. A vast body of literature has shown that mitochondria from AD patients and model organisms of the disease differ from their non-AD counterparts. In view of this evidence, preserving and/or restoring mitochondria's health and function can represent the primary means to achieve advances to tackle AD. In this review, we will briefly assess and summarize the previous and latest evidence of mitochondria dysfunction in AD. A particular focus will be given to the recent updates and advances in the strategy options aimed to target faulty mitochondria in AD.

Current and future therapeutic strategies for Alzheimer's disease: an overview of drug development bottlenecks

Alzheimer's disease (AD) is the most common chronic neurodegenerative disease worldwide. It causes cognitive dysfunction, such as aphasia and agnosia, and mental symptoms, such as behavioral abnormalities; all of which place a significant psychological and economic burden on the patients' families. No specific drugs are currently available for the treatment of AD, and the current drugs for AD only delay disease onset and progression. The pathophysiological basis of AD involves abnormal deposition of beta-amyloid protein (Aβ), abnormal tau protein phosphorylation, decreased activity of acetylcholine content, glutamate toxicity, autophagy, inflammatory reactions, mitochondria-targeting, and multi-targets. The US Food and Drug Administration (FDA) has approved five drugs for clinical use: tacrine, donepezil, carbalatine, galantamine, memantine, and lecanemab. We have focused on the newer drugs that have undergone clinical trials, most of which have not been successful as a result of excessive clinical side effects or poor efficacy. Although aducanumab received rapid approval from the FDA on 7 June 2021, its long-term safety and tolerability require further monitoring and confirmation. In this literature review, we aimed to explore the possible pathophysiological mechanisms underlying the occurrence and development of AD. We focused on anti-Aβ and anti-tau drugs, mitochondria-targeting and multi-targets, commercially available drugs, bottlenecks encountered in drug development, and the possible targets and therapeutic strategies for future drug development. We hope to present new concepts and methods for future drug therapies for AD.

Axonal energy metabolism, and the effects in aging and neurodegenerative diseases

Human studies consistently identify bioenergetic maladaptations in brains upon aging and neurodegenerative disorders of aging (NDAs), such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Glucose is the major brain fuel and glucose hypometabolism has been observed in brain regions vulnerable to aging and NDAs. Many neurodegenerative susceptible regions are in the topological central hub of the brain connectome, linked by densely interconnected long-range axons. Axons, key components of the connectome, have high metabolic needs to support neurotransmission and other essential activities. Long-range axons are particularly vulnerable to injury, neurotoxin exposure, protein stress, lysosomal dysfunction, etc. Axonopathy is often an early sign of neurodegeneration. Recent studies ascribe axonal maintenance failures to local bioenergetic dysregulation. With this review, we aim to stimulate research in exploring metabolically oriented neuroprotection strategies to enhance or normalize bioenergetics in NDA models. Here we start by summarizing evidence from human patients and animal models to reveal the correlation between glucose hypometabolism and connectomic disintegration upon aging/NDAs. To encourage mechanistic investigations on how axonal bioenergetic dysregulation occurs during aging/NDAs, we first review the current literature on axonal bioenergetics in distinct axonal subdomains: axon initial segments, myelinated axonal segments, and axonal arbors harboring pre-synaptic boutons. In each subdomain, we focus on the organization, activity-dependent regulation of the bioenergetic system, and external glial support. Second, we review the mechanisms regulating axonal nicotinamide adenine dinucleotide (NAD+) homeostasis, an essential molecule for energy metabolism processes, including NAD+ biosynthetic, recycling, and consuming pathways. Third, we highlight the innate metabolic vulnerability of the brain connectome and discuss its perturbation during aging and NDAs. As axonal bioenergetic deficits are developing into NDAs, especially in asymptomatic phase, they are likely exaggerated further by impaired NAD+ homeostasis, the high energetic cost of neural network hyperactivity, and glial pathology. Future research in interrogating the causal relationship between metabolic vulnerability, axonopathy, amyloid/tau pathology, and cognitive decline will provide fundamental knowledge for developing therapeutic interventions.

Myricetin improves pathological changes in 3×Tg-AD mice by regulating the mitochondria-NLRP3 inflammasome-microglia channel by targeting P38 MAPK signaling pathway

BACKGROUND

Alzheimer's disease (AD) represents the common neurodegenerative disease featured by the manifestations of cognitive impairment and memory loss. AD could be alleviated with medication and improving quality of life. Clinical treatment of AD is mainly aimed at improving the cognitive function of patients. Donepezil, memantine and galantamine are commonly used drug. But they could only relieve AD, not cure it. Therefore, new treatment strategies focusing on AD pathogenesis are of great significance and value. Myricetin (Myr) is a natural flavonoid extracted from Myrica rubra. And it shows different bioactivities, such as anti-inflammation, antioxidation as well as central nervous system (CNS) activities. Nonetheless, its associated mechanism in treating AD remains unknown.

PURPOSE

Here we focused on investigating Myr's effect on treating AD and exploring if its protection on the nervous system activity was associated with specifically inhibiting P38 MAPK signaling pathway while regulating mitochondria-NLRP3 inflammasome-microglia.

STUDY DESIGN AND METHODS

This work utilized triple transgenic mice (3 × Tg-AD) as AD models and Aβ_25-35 was used to induce BV2 cells to build an in vitro AD model. Behavioristics, pathology and related inflammatory factors were examined. Molecular mechanisms are investigated by western-blot, immunofluorescence staining, CETSA, molecular docking, network pharmacology.

RESULTS

According to our findings, Myr could remarkably improve memory loss, spatial learning ability, Aβ plaque deposition, neuronal and synaptic damage in 3 × Tg-AD mice through specifically inhibiting P38 MAPK pathway activation while restraining microglial hyperactivation. Furthermore, Myr promoted the transformation of microglial phenotype, restored the mitochondrial fission-fusion balance, facilitated mitochondrial biogenesis, and restrained NLRP3 inflammasome activation and neuroinflammation. For the in-vitro experiments, P38 agonist dehydrocorydaline (DHC) was utilized to confirm the key regulatory role of P38 MAPK signaling pathway on the mitochondria-NLRP3 inflammasome-microglia channel.

CONCLUSIONS

Our results revealed the therapeutic efficacy of Myr in experimental AD, and implied that the associated mechanism is possibly associated with inhibiting tmitochondrial dysfunction, activating NLRP3 inflammasome, and neuroinflammation which was mediated by P38 MAPK pathway. Myr is the drug candidate in AD therapy via targeting P38 MAPK pathway.

Dietary choline intake is necessary to prevent systems-wide organ pathology and reduce Alzheimer's disease hallmarks

There is an urgent need to identify modifiable environmental risk factors that reduce the incidence of Alzheimer's disease (AD). The B-like vitamin choline plays key roles in body- and brain-related functions. Choline produced endogenously by the phosphatidylethanolamine N-methyltransferase protein in the liver is not sufficient for adequate physiological functions, necessitating daily dietary intake. ~90% of Americans do not reach the recommended daily intake of dietary choline. Thus, it's imperative to determine whether dietary choline deficiency increases disease outcomes. Here, we placed 3xTg-AD, a model of AD, and non-transgenic (NonTg) control mice on either a standard laboratory diet with sufficient choline (ChN; 2.0 g/kg choline bitartrate) or a choline-deficient diet (Ch-; 0.0 g/kg choline bitartrate) from 3 to 12 (early to late adulthood) months of age. A Ch- diet reduced blood plasma choline levels, increased weight, and impaired both motor function and glucose metabolism in NonTg mice, with 3xTg-AD mice showing greater deficits. Tissue analyses showed cardiac and liver pathology, elevated soluble and insoluble Amyloid-β and Thioflavin S structures, and tau hyperphosphorylation at various pathological epitopes in the hippocampus and cortex of 3xTg-AD Ch- mice. To gain mechanistic insight, we performed unbiased proteomics of hippocampal and blood plasma samples. Dietary choline deficiency altered hippocampal networks associated with microtubule function and postsynaptic membrane regulation. In plasma, dietary choline deficiency altered protein networks associated with insulin metabolism, mitochondrial function, inflammation, and fructose metabolic processing. Our data highlight that dietary choline intake is necessary to prevent systems-wide organ pathology and reduce hallmark AD pathologies.

Targeting Novel microRNAs in Developing Novel Alzheimer's Disease Treatments

Alzheimer's disease (AD) is considered a multifactorial disease and a significant cause of dementia during aging. This neurodegenerative disease process is classically divided into two different pathologies cerebral accumulation of amyloid-β and hyperphosphorylated neurofibrillary tau tangles. In recent years, massive efforts have been made to treat AD by decreasing amyloid-β and tau in the brains of patients with AD, with no success. The dysfunction of a wide range of microRNAs promotes the generation and insufficient clearance of amyloid-β (Aβ) and increases tau plaques which are the pathophysiological markers of AD. Disturbance of these microRNAs is associated with mitochondrial dysfunction, oxidative damage, inflammation, apolipoprotein E4 (APOE4) pathogenic process, synaptic loss, and cognitive deficits induced by AD. Targeting a specific microRNA to restore AD-induced impairments at multiple stages might provide a promising approach for developing new drugs and therapeutic strategies for patients with AD. This review focuses on different mechanisms of microRNAs in AD pathophysiology.

Glucocorticoids decrease thermogenic capacity and increase triacylglycerol synthesis by glycerokinase activation in the brown adipose tissue of rats

Although it is well established that glucocorticoids inactivate thermogenesis and promote lipid accumulation in interscapular brown adipose tissue (IBAT), the underlying mechanisms remain unknown. We found that dexamethasone treatment (1 mg/kg) for 7 days in rats decreased the IBAT thermogenic activity, evidenced by its lower responsiveness to noradrenaline injection associated with reduced content of mitochondrial proteins, respiratory chain protein complexes, noradrenaline, and the β₃ -adrenergic receptor. In parallel, to understand better how dexamethasone increases IBAT lipid content, we also investigated the activity of the ATP citrate lyase (ACL), a key enzyme of de novo fatty acid synthesis, glucose-6-phosphate dehydrogenase (G6PD), a rate-limiting enzyme of the pentose phosphate pathway, and the three glycerol-3-P generating pathways: (1) glycolysis, estimated by 2-deoxyglucose uptake, (2) glyceroneogenesis, evaluated by phosphoenolpyruvate carboxykinase activity and pyruvate incorporation into triacylglycerol-glycerol, and (3) direct phosphorylation of glycerol, investigated by the content and activity of glycerokinase. Dexamethasone increased the mass and the lipid content of IBAT as well as plasma levels of glucose, insulin, non-esterified fatty acid, and glycerol. Furthermore, dexamethasone increased ACL and G6PD activities (79% and 48%, respectively). Despite promoting a decrease in the incorporation of U-[¹⁴ C]-glycerol into triacylglycerol (~54%), dexamethasone increased the content (~55%) and activity (~41%) of glycerokinase without affecting glucose uptake or glyceroneogenesis. Our data suggest that glucocorticoid administration reduces IBAT thermogenesis through sympathetic inactivation and stimulates glycerokinase activity and content, contributing to increased generation of glycerol-3-P, which is mostly used to esterify fatty acid and increase triacylglycerol content promoting IBAT whitening.

Cholinergic Neuron Targeting Nanosystem Delivering Hybrid Peptide for Combinatorial Mitochondrial Therapy in Alzheimer's Disease

Mitochondrial dysfunction in neurons has recently become a promising therapeutic target for Alzheimer's disease (AD). Regulation of dysfunctional mitochondria through multiple pathways rather than antioxidation monotherapy indicates synergistic therapeutic effects. Therefore, we developed a multifunctional hybrid peptide HNSS composed of antioxidant peptide SS31 and neuroprotective peptide S14G-Humanin. However, suitable peptide delivery systems with excellent loading capacity and effective at-site delivery are still absent. Herein, the nanoparticles made of citraconylation-modified poly(ethylene glycol)-poly(trimethylene carbonate) polymer (PEG-PTMC(Cit)) exhibited desirable loading of HNSS peptide through electrostatic interactions. Meanwhile, based on fibroblast growth factor receptor 1(FGFR1) overexpression in both the blood-brain barrier and cholinergic neuron, an FGFR1 ligand-FGL peptide was modified on the nanosystem (FGL-NP(Cit)/HNSS) to achieve 4.8-fold enhanced accumulation in brain with preferred distribution into cholinergic neurons in the diseased region. The acid-sensitive property of the nanosystem facilitated lysosomal escape and intracellular drug release by charge switching, resulting in HNSS enrichment in mitochondria through directing of the SS31 part. FGL-NP(Cit)/HNSS effectively rescued mitochondria dysfunction via the PGC-1α and STAT3 pathways, inhibited Aβ deposition and tau hyperphosphorylation, and ameliorated memory defects and cholinergic neuronal damage in 3xTg-AD mice. The work provides a potential platform for targeted cationic peptide delivery, harboring utility for peptide therapy in other neurodegenerative diseases.

GSH-AuNP anti-oxidative stress, ER stress and mitochondrial dysfunction in amyloid-beta peptide-treated human neural stem cells

Amyloid-beta (Aβ) peptides have a role in the pathogenesis of Alzheimer's disease (AD) and are thought to promote oxidative stress, endoplasmic reticulum (ER) stress and mitochondrial deficiency, causing neuronal loss in the AD brain. The potential applications of glutathione conjugated gold nanoparticles (GSH-AuNPs) suggest they might have therapeutic value. Several studies have demonstrated that the effects of nanoparticles could provide protective roles in AD. Here, we showed that GSH-AuNPs mediate the viability of human neural stem cells (hNSCs) with Aβ, which was correlated with decreased caspase 3 and caspase 9. Importantly, hNSCs co-treated with GSH-AuNPs were significantly protected from Aβ-induced oxidative stress, as detected using the DCFH-DA, DHE, and MitoSOX staining assays. Furthermore, hNSCs co-treated with GSH-AuNPs were significantly protected from the Aβ-induced reduction in the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2 downstream antioxidant target genes (SOD-1, SOD-2, Gpx, Catalase, and HO-1). In addition, GSH-AuNPs rescued the expression levels of ER stress-associated genes (Bip, CHOP, and ASK1) in Aβ-treated hNSCs. GSH-AuNPs normalized ER calcium and mitochondrial cytochrome c homeostasis in Aβ-treated hNSCs. Furthermore, treatment with GSH-AuNPs restored the levels of ATP, D-loop, mitochondrial mass, basal respiration, ATP-linked reparation, maximal respiration capacity, COX activity, mitochondrial membrane potential, and mitochondrial genes (PGC1α, NRF-1 and Tfam) in Aβ-treated hNSCs. Taken together, these findings extend our understanding of the protective effects of GSH-AuNPs against oxidative stress, ER stress and mitochondrial dysfunction in hNSCs with Aβ.

Biochanin A alleviates cognitive impairment and hippocampal mitochondrial damage in ovariectomized APP/PS1 mice

BACKGROUND

Estrogen deficiency leads to mitochondrial defects that precede Alzheimer's disease (AD)-associated pathological changes in a postmenopausal mouse model. Biochanin A (BCA) is a phytoestrogen isolated from Trifolium pratense L. used to relieve postmenopausal problems in women. In previous work, we observed that oral BCA treatment led to neuroprotection in an ovariectomized rat model. The objective of this study was to investigate whether and how BCA protects against hippocampal mitochondrial damage in a postmenopausal model of AD.

METHOD

APP/PS1 mice underwent bilateral ovariectomy and then, seven days later, received oral BCA at 20 or 40 mg/kg, or oral estradiol at 0.5 mg/kg, daily for 90 days. Sham animals were not ovariectomized and received no additional treatments. Cognitive function was examined using the passive avoidance task, novel object recognition test, and Morris water maze test. The level of circulating estrogen in vivo was assessed indirectly by measuring the wet weight of the uterus. We detected Aβ deposition and PGC-1α in brain by immunohistochemistry; p62, by immunofluorescence; and ERα, ERβ, PGC-1α, NRF1, mtTFA, Drp1, OPA1, Mfn2, Beclin1, LC3B, Pink1, and Parkin by immunoblotting.

RESULTS

BCA treatment rescued cognitive decline and reduced Aβ deposition and BACE1 expression in the hippocampus of ovariectomized APP/PS1 mice. BCA reversed the imbalance of mitochondrial dynamics caused by ovariectomy by increasing the expression of phospho-Drp1 (ser637), OPA1, and Mfn2. BCA reversed abnormal mitophagy induced by ovariectomy by increasing the expression of Beclin1, LC3B, Pink1, and Parkin, as well as by reducing the expression of p62.

CONCLUSIONS

BCA treatment enhances learning and memory abilities and alleviates AD symptoms in a postmenopausal model of AD. A possible mechanism is that BCA rescues the reduction of mitochondrial biogenesis, imbalance of mitochondrial dynamics, and abnormal mitophagy caused by ovariectomy. This study supports further research on BCA to develop treatments for postmenopausal women with AD.

Age-Dependent Alterations of Cognition, Mitochondrial Function, and Beta-Amyloid Deposition in a Murine Model of Alzheimer’s Disease—A Longitudinal Study

Aging is the main risk factor for sporadic Alzheimer’s disease (AD), which is characterized by the cerebral deposition of β-amyloid peptides (Aβ) and cognitive decline. Mitochondrial dysfunction is also characteristic of the disease and represents a hallmark of both, aging and neurodegeneration. We longitudinally followed Aβ levels, cognition, and mitochondrial function in the same cohort of Thy1-APP₇₅₁SL mice representing a murine model of AD. In the course of time, changes were most prominent at an age of 13 months including the latency time in the passive avoidance test, the activity of complexes I and IV of the mitochondrial respiration chain, and expression of genes related to mitochondrial biogenesis and synaptic plasticity including Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), CAMP responsive element binding protein 1 (CREB1), and Synaptophysin 1 (SYP1). These changes occurred in parallel with massively increasing cerebral Aβ levels. Other parameters were changed in younger mice including the alteration rate in the Y-maze test and the nesting score when Aβ levels were not changed yet. The results are consistent in the cohort described. However, previous, non-longitudinal studies reported divergent time points for the occurrence of the parameters studied. These findings are discussed in light of the current results.

Rhein Ameliorates Cognitive Impairment in an APP/PS1 Transgenic Mouse Model of Alzheimer's Disease by Relieving Oxidative Stress through Activating the SIRT1/PGC-1α Pathway

Mitochondrial oxidative stress plays an important role in the pathogenesis of Alzheimer's disease (AD). Recently, antioxidant therapy has been considered an effective strategy for the treatment of AD. Our previous work discovered that rhein relieved mitochondrial oxidative stress in β-amyloid (Aβ) oligomer-induced primary neurons by improving the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator 1-alpha- (PGC-1α-) regulated mitochondrial biogenesis. While encouraging results have been provided, mechanisms underlying the beneficial effect of rhein on AD are yet to be elucidated in vivo. In this study, we evaluated the therapeutic effect of rhein on an APP/PS1 transgenic (APP/PS1) mouse model of AD and explored its antioxidant mechanisms. As a result, rhein significantly reduced Aβ burden and neuroinflammation and eventually ameliorated cognitive impairment in APP/PS1 mice. Moreover, rhein reversed oxidative stress in the brain of APP/PS1 mice and protected neurons from oxidative stress-associated apoptosis. Further study revealed that rhein promoted mitochondrial biogenesis against oxidative stress by upregulating SIRT1 and its downstream PGC-1α as well as nuclear respiratory factor 1. Improved mitochondrial biogenesis not only increased the activity of superoxide dismutase to scavenge excess reactive oxygen species (ROS) but also repaired mitochondria by mitochondrial fusion to inhibit the production of ROS from the electron transport chain. Notably, the exposure of rhein in the brain analyzed by tissue distribution study indicated that rhein could permeate into the brain to exert its therapeutic effects. In conclusion, these findings drive rhein to serve as a promising therapeutic antioxidant for the treatment of AD. Our research highlights the therapeutic efficacy for AD through regulating mitochondrial biogenesis via the SIRT1/PGC-1α pathway.

Mitochondrial Dysfunction in Alzheimer's Disease: Opportunities for Drug Development

Alzheimer's disease (AD) is one of the major reasons for 60-80% cases of senile dementia occurring as a result of the accumulation of plaques and tangles in the hippocampal and cortical neurons of the brain leading to neurodegeneration and cell death. The other pathological features of AD comprise abnormal microvasculature, network abnormalities, interneuronal dysfunction, increased β-amyloid production and reduced clearance, increased inflammatory response, elevated production of reactive oxygen species, impaired brain metabolism, hyperphosphorylation of tau, and disruption of acetylcholine signaling. Among all these pathologies, Mitochondrial Dysfunction (MD), regardless of it being an inciting insult or a consequence of the alterations, is related to all the associated AD pathologies. Observed altered mitochondrial morphology, distribution and movement, increased oxidative stress, dysregulation of enzymes involved in mitochondrial functioning, impaired brain metabolism, and impaired mitochondrial biogenesis in AD subjects suggest the involvement of mitochondrial malfunction in the progression of AD. Here, various pre-clinical and clinical evidence establishing MD as a key mediator in the progression of neurodegeneration in AD are reviewed and discussed with an aim to foster future MD based drug development research for the management of AD.

Inhibition of TRPM2 by AG490 Is Neuroprotective in a Parkinson's Disease Animal Model

Parkinson's disease (PD) is characterized by motor impairment and dopaminergic neuronal loss. There is no cure for the disease, and treatments have several limitations. The transient receptor potential melastatin 2 (TRPM2), a calcium-permeable non-selective cation channel, has been reported to be upregulated in neuronal death. However, there are no in vivo studies evaluating TRPM2's role and neuroprotective effects in PD. Here, we test the hypothesis that TRPM2 is upregulated in the 6-hydroxydopamine (6-OHDA) mouse model of PD and that its inhibition, by the AG490, is neuroprotective. For that, AG490 or vehicle were intraperitoneally administered into C57BL/6 mice. Mice then received 6-OHDA into the right striatum. Motor behavior assessments were evaluated 6, 13, and 20 days after surgery using the cylinder and apomorphine-induced rotational testes, and 7, 14, and 21 days after surgery using rotarod test. Brain samples of substantia nigra (SNc) and striatum (CPu) were collected for immunohistochemistry and immunoblotting on days 7 and 21. We showed that TRPM2 protein expression was upregulated in 6-OHDA-treated animals. In addition, AG490 prevented dopaminergic neuron loss, microglial activation, and astrocyte reactivity in 6-OHDA-treated animals. The compound improved motor behaviors and Akt/GSK-3β/caspase-3 signaling. We conclude that TRPM2 inhibition by AG490 is neuroprotective in the 6-OHDA model and that the TRPM2 channel may represent a potential therapeutic target for PD.

Deciphering the role of PGC-1α in neurological disorders: from mitochondrial dysfunction to synaptic failure

The onset and mechanisms underlying neurodegenerative diseases remain uncertain. The main features of neurodegenerative diseases have been related with cellular and molecular events like neuronal loss, mitochondrial dysfunction and aberrant accumulation of misfolded proteins or peptides in specific areas of the brain. The most prevalent neurodegenerative diseases belonging to age-related pathologies are Alzheimer's disease, Huntington's disease, Parkinson's disease and amyotrophic lateral sclerosis. Interestingly, mitochondrial dysfunction has been observed to occur during the early onset of several neuropathological events associated to neurodegenerative diseases. The master regulator of mitochondrial quality control and energetic metabolism is the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Additionally, it has been observed that PGC-1α appears to be a key factor in maintaining neuronal survival and synaptic transmission. In fact, PGC-1α downregulation in different brain areas (hippocampus, substantia nigra, cortex, striatum and spinal cord) that occurs in function of neurological damage including oxidative stress, neuronal loss, and motor disorders has been seen in several animal and cellular models of neurodegenerative diseases. Current evidence indicates that PGC-1α upregulation may serve as a potent therapeutic approach against development and progression of neuronal damage. Remarkably, increasing evidence shows that PGC-1α deficient mice have neurodegenerative diseases-like features, as well as neurological abnormalities. Finally, we discuss recent studies showing novel specific PGC-1α isoforms in the central nervous system that appear to exert a key role in the age of onset of neurodegenerative diseases and have a neuroprotective function in the central nervous system, thus opening a new molecular strategy for treatment of neurodegenerative diseases. The purpose of this review is to provide an up-to-date overview of the PGC-1α role in the physiopathology of neurodegenerative diseases, as well as establish the importance of PGC-1α function in synaptic transmission and neuronal survival.

Neuroplasticity induced by the retention period of a complex motor skill learning in rats

Learning complex motor skills is an essential process in our daily lives. Moreover, it is an important aspect for the development of therapeutic strategies that refer to rehabilitation processes since motor skills previously acquired can be transferred to similar tasks (motor skill transfer) or recovered without further practice after longer delays (motor skill retention). Different acrobatic exercise training (AE) protocols induce plastic changes in areas involved in motor control and improvement in motor performance. However, the plastic mechanisms involved in the retention of a complex motor skill, essential for motor learning, are not well described. Thus, our objective was to analyze the brain plasticity mechanisms involved in motor skill retention in AE . Motor behavior tests, and the expression of synaptophysin (SYP), synapsin-I (SYS), and early growth response protein 1 (Egr-1) in brain areas involved in motor learning were evaluated. Young male Wistar rats were randomly divided into 3 groups: sedentary (SED), AE, and AE with retention period (AER). AE was performed three times a week for 8 weeks, with 5 rounds in the circuit. After a fifteen-day retention interval, the AER animals was again exposed to the acrobatic circuit. Our results revealed motor performance improvement in the AE and AER groups. In the elevated beam test, the AER group presented a lower time and greater distance, suggesting retention period is important for optimizing motor learning consolidation. Moreover, AE promoted significant plastic changes in the expression of proteins in important areas involved in control and motor learning, some of which were maintained in the AER group. In summary, these data contribute to the understanding of neural mechanisms involved in motor learning in an animal model, and can be useful to the construction of therapeutics strategies that optimize motor learning in a rehabilitative context.

Alzheimer's Disease: A Molecular View of β-Amyloid Induced Morbific Events

Amyloid-β (Aβ) is a dynamic peptide of Alzheimer’s disease (AD) which accelerates the disease progression. At the cell membrane and cell compartments, the amyloid precursor protein (APP) undergoes amyloidogenic cleavage by β- and γ-secretases and engenders the Aβ. In addition, externally produced Aβ gets inside the cells by receptors mediated internalization. An elevated amount of Aβ yields spontaneous aggregation which causes organelles impairment. Aβ stimulates the hyperphosphorylation of tau protein via acceleration by several kinases. Aβ travels to the mitochondria and interacts with its functional complexes, which impairs the mitochondrial function leading to the activation of apoptotic signaling cascade. Aβ disrupts the Ca²⁺ and protein homeostasis of the endoplasmic reticulum (ER) and Golgi complex (GC) that promotes the organelle stress and inhibits its stress recovery machinery such as unfolded protein response (UPR) and ER-associated degradation (ERAD). At lysosome, Aβ precedes autophagy dysfunction upon interacting with autophagy molecules. Interestingly, Aβ act as a transcription regulator as well as inhibits telomerase activity. Both Aβ and p-tau interaction with neuronal and glial receptors elevate the inflammatory molecules and persuade inflammation. Here, we have expounded the Aβ mediated events in the cells and its cosmopolitan role on neurodegeneration, and the current clinical status of anti-amyloid therapy.

Effects of Iron and Zinc on Mitochondria: Potential Mechanisms of Glaucomatous Injury

Glaucoma is the most substantial cause of irreversible blinding, which is accompanied by progressive retinal ganglion cell damage. Retinal ganglion cells are energy-intensive neurons that connect the brain and retina, and depend on mitochondrial homeostasis to transduce visual information through the brain. As cofactors that regulate many metabolic signals, iron and zinc have attracted increasing attention in studies on neurons and neurodegenerative diseases. Here, we summarize the research connecting iron, zinc, neuronal mitochondria, and glaucomatous injury, with the aim of updating and expanding the current view of how retinal ganglion cells degenerate in glaucoma, which can reveal novel potential targets for neuroprotection.

Estrogen Deficiency Induces Mitochondrial Damage Prior to Emergence of Cognitive Deficits in a Postmenopausal Mouse Model

Background: Estrogen deficiency contributes to the development of Alzheimer's disease (AD) in menopausal women. In the current study, we examined the impact of estrogen deficiency on mitochondrial function and cognition using a postmenopausal mouse model. Methods: Bilateral ovariectomy was conducted in adult females C57BL/6J. Cognitive function was examined using the Morris water maze (MWM) test at 2 weeks, 1, 2, and 3 months after ovariectomy. Neurodegeneration was assessed using an immunofluorescence assay of microtubule-associated protein 2 (MAP2) in the hippocampus and immunoblotting against postsynaptic density-95 (PSD95). Mitochondrial function in the hippocampus was assessed using immunoblotting for NDUFB8, SDHB, UQCRC2, MTCO1, and ATP5A1. Mitochondrial biogenesis was examined using immunoblotting for PGC-1α, NRF1, and mtTFA. Mitochondrion fission was assessed with immunoblotting for Drp1, whereas mitochondrion fusion was analyzed with immunoblotting for OPA1 and Mfn2. Mitophagy was examined with immunoblotting for PINK1 and LC3B. Mice receiving sham surgery were used as controls. Results: Ovariectomy resulted in significant learning and memory deficits in the MWM test at 3 months, but not at any earlier time points. At 2 weeks after ovariectomy, levels of Drp1 phosphorylated at Ser637 decreased in the hippocampus. At 1 month after ovariectomy, hippocampal levels of NDUFB8, SDHB, PGC-1α, mtTFA, OPA1, and Mfn2 were significantly reduced. At 2 months after ovariectomy, hippocampal levels of MAP2, PSD95, MTCO1, NRF1, and Pink1 were also reduced. At 3 months, levels of LC3B-II were reduced. Conclusions: The cognitive decline associated with estrogen deficiency is preceded by mitochondrial dysfunction, abnormal mitochondrial biogenesis, irregular mitochondrial dynamics, and decreased mitophagy. Thus, mitochondrial damage may contribute to cognitive impairment associated with estrogen deficiency.

Mitochondrial dysfunction in Alzheimer's disease: Therapeutic implications of lithium

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases, characterized by the accumulation of abnormal tau proteins within neurons and amyloid plaques in the brain parenchyma, which leads to progressive loss of neurons in the brain. While the detailed mechanism of the pathogenesis of AD is still unknown, evidence suggests that mitochondrial dysfunction likely plays a fundamental role in the pathogenesis of this disease. Due to the relevance of mitochondrial alterations in AD, recent works have suggested the therapeutic potential of mitochondrial-targeted lithium. Lithium has been shown to possess neuroprotective and neurotrophic properties that could also be related to the upregulation of mitochondrial function. In the current work, we perform a comprehensive investigation of the significance of mitochondrial dysfunction in AD and pharmacological treatment with lithium as imperative in this pathology, through a brief review of the major findings on the effects of lithium as a therapeutic approach targeting mitochondria in the context of AD.

Mitochondrial dysfunction: A potential target for Alzheimer's disease intervention and treatment

Alzheimer's disease (AD) is an irreversible neurodegenerative brain disorder which manifests as a progressive decline in cognitive function. Mitochondrial dysfunction plays a critical role in the early stages of AD, and advances the progression of this age-related neurodegenerative disorder. Therefore, it can be a potential target for interventions to treat AD. Several therapeutic strategies to target mitochondrial dysfunction have gained significant attention in the preclinical stage, but the clinical trials performed to date have shown little progress. Thus, we discuss the mechanisms and strategies of different therapeutic agents for targeting mitochondrial dysfunction in AD. We hope that this review will inspire and guide the development of efficient AD drugs in the future.

The nuclear factor kappa B (NF-κB) signaling pathway is involved in ammonia-induced mitochondrial dysfunction

Hyperammonemia is very toxic to the brain, leading to inflammation, disruption of brain cellular energy metabolism and cognitive function. However, the underlying mechanism(s) for these impairments is still not fully understood. This study investigated the effects of ammonia in hippocampal astroglia derived from C57BL/6 mice. Parameters measured included oxygen consumption rates (OCR), ATP, cytochrome c oxidase (COX) activity, alterations in oxidative phosphorylation (OXPHOS), nuclear factor kappa B (NF-κB) subunits, key regulators of mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α), calcium/calmodulin-dependent protein kinase II (CaMKII), cAMP-response element binding protein (CREB), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), early growth response (Egr) factor family of proteins, and mitochondrial transcription factor A (TFAM). Ammonia was found to decrease mitochondrial numbers, potentially through a CaMKII-CREB-PGC1α-Nrf2 pathway in astroglia. Ammonia did not alter the levels of Egrs and TFAM in astroglia. Ammonia decreased OCR, ATP, COX, and OXPHOS levels in astroglia. To assess whether energy metabolism is reduced by ammonia through NF-κB associated pathways, astroglia were treated with ammonia alone or with NF-κB inhibitors such as Bay11-7082 or SN50. Mitochondrial OCR levels were reduced in the presence of NF-κB inhibitors; however co-treatment of NF-κB inhibitors and ammonia reversed mitochondrial deficits. Further, ammonia increased translocation of the NF-κB p65 into the nucleus of astroglia that correlates with an increased activity of NF-κB. These findings suggest that the NF-κB signaling pathway is putatively involved in ammonia-induced changes in bioenergetics in astroglia. Such research has critical implications for the treatment of disorders in which brain bioenergetics is compromised.

Mitochondria as a promising target for developing novel agents for treating Alzheimer's disease

The mitochondria-targeting drugs can be conventionally divided into the following groups: those compensating for the energy deficit involved in neurodegeneration, including stimulants of mitochondrial bioenergetics and activators of mitochondrial biogenesis; and neuroprotectors, that are compounds increasing the resistance of mitochondria to opening of mitochondrial permeability transition (MPT) pores. Although compensating for the energy deficit and inhibition of MPT are obvious targets for drugs used in the very early stages of Alzheimer-like pathology, but their use as the monotherapy for patients with severe symptoms is unlikely to be sufficiently effective. It would be optimal to combine targets that would provide the cognitive-stimulating, the neuroprotective effects and the ability to affect specific disease-forming mechanisms. In the design of such drugs, assessment of their potential mitochondrial-targeted effects is of particular importance. The possibility of targeted drug design for simultaneous action on mitochondrial and neurotransmitter's receptors targets is, in particularly, based on the known interplay of various cellular pathways and the presence of common structural components. Of particular interest is directed search for multitarget drugs that would act simultaneously on mitochondrial calcium-dependent functions, the targets (receptors, enzymes, etc.) facilitating neurotransmission, and the molecular targets related to the action of so-called disease-modifying factors, in particular, the formation and overcoming of the toxicity of β-amyloid or hyperphosphorylated tau protein. The examples of such approaches realized on the level of preclinical and clinical trials are presented below.

Phosphodiesterase Inhibitors for Alzheimer's Disease: A Systematic Review of Clinical Trials and Epidemiology with a Mechanistic Rationale

BACKGROUND

Preclinical studies, clinical trials, and reviews suggest increasing 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) with phosphodiesterase inhibitors is disease-modifying in Alzheimer's disease (AD). cAMP/protein kinase A (PKA) and cGMP/protein kinase G (PKG) signaling are disrupted in AD. cAMP/PKA and cGMP/PKG activate cAMP response element binding protein (CREB). CREB binds mitochondrial and nuclear DNA, inducing synaptogenesis, memory, and neuronal survival gene (e.g., brain-derived neurotrophic factor) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α). cAMP/PKA and cGMP/PKG activate Sirtuin-1, which activates PGC1α. PGC1α induces mitochondrial biogenesis and antioxidant genes (e.g.,Nrf2) and represses BACE1. cAMP and cGMP inhibit BACE1-inducing NFκB and tau-phosphorylating GSK3β.

OBJECTIVE AND METHODS

We review efficacy-testing clinical trials, epidemiology, and meta-analyses to critically investigate whether phosphodiesteraseinhibitors prevent or treat AD.

RESULTS

Caffeine and cilostazol may lower AD risk. Denbufylline and sildenafil clinical trials are promising but preliminary and inconclusive. PF-04447943 and BI 409,306 are ineffective. Vinpocetine, cilostazol, and nicergoline trials are mixed. Deprenyl/selegiline trials show only short-term benefits. Broad-spectrum phosphodiesterase inhibitor propentofylline has been shown in five phase III trials to improve cognition, dementia severity, activities of daily living, and global assessment in mild-to-moderate AD patients on multiple scales, including the ADAS-Cogand the CIBIC-Plus in an 18-month phase III clinical trial. However, two books claimed based on a MedScape article an 18-month phase III trial failed, so propentofylline was discontinued. Now, propentofylline is used to treat canine cognitive dysfunction, which, like AD, involves age-associated wild-type Aβ deposition.

CONCLUSION

Phosphodiesterase inhibitors may prevent and treat AD.

Physical exercise protects against mitochondria alterations in the 6-hidroxydopamine rat model of Parkinson's disease

Parkinson's disease (PD) is typicaly caractherized by loss of dopaminergic neurons, as well as the presence of mitochondrial impairments. Although physical exercise is known to promote many beneficial effects in healthy subjects, such as enhancing mitocondrial biogenesis and function, it is not clear if these effects are evident after exercise in individuals with PD. The aim of this study was to investigate the effects of two different protocol durations on motor behavior (aphomorphine and gait tests), mitochondrial biogenesis signaling (PGC-1α, NRF-1 and TFAM), structure (oxidative phosphorylation system protein levels) and respiratory chain activity (complex I) in a unilateral PD rat model. For this, male Wistar rats were injected with 6-hydroxydopamine unilaterally into the striatum and submitted to an intermitent moderate treadmill exercise for one or four weeks. In the gait test, only stride width data revealed an improvement after one week of exercise. On the other hand, after 4 weeks of the exercise protocol all gait parameters analyzed and the aphomorphine test demonstrated a recovery. Analysis of protein revealed that one week of exercise was able to prevent PGC-1α and NRF-1 expression decrease in PD animals. In addition, after four weeks of physical exercise, besides PGC-1α and NRF-1, reduction in TFAM and complex I protein levels and increased complex I activity were also prevented in PD animals. Thus, our results suggest a neuroprotective and progressive effect of intermittent treadmill exercise, which could be related to its benefits on mitochondrial biogenesis signaling and respiratory chain modulation of the dopaminergic system in PD.

Curcumin in Health and Diseases: Alzheimer's Disease and Curcumin Analogues, Derivatives, and Hybrids

Worldwide, Alzheimer’s disease (AD) is the most common neurodegenerative multifactorial disease influencing the elderly population. Nowadays, several medications, among them curcumin, are used in the treatment of AD. Curcumin, which is the principal component of Curcuma longa, has shown favorable effects forsignificantly preventing or treating AD. During the last decade, the scientific community has focused their research on the optimization of therapeutic properties and on the improvement of pharmacokinetic properties of curcumin. This review summarizes bibliographical data from 2009 to 2019 on curcumin analogues, derivatives, and hybrids, as well as their therapeutic, preventic, and diagnostic applications in AD. Recent advances in the field have revealed that the phenolic hydroxyl group could contribute to the anti-amyloidogenic activity. Phenyl methoxy groups seem to contribute to the suppression of amyloid-β peptide (Aβ₄₂) and to the suppression of amyloid precursor protein (APP) andhydrophobic interactions have also revealed a growing role. Furthermore, flexible moieties, at the linker, are crucial for the inhibition of Aβ aggregation. The inhibitory activity of derivatives is increased with the expansion of the aromatic rings. The promising role of curcumin-based compounds in diagnostic imaging is highlighted. The keto-enol tautomerism seems to be a novel modification for the design of amyloid-binding agents. Molecular docking results, (Q)SAR, as well as in vitro and in vivo tests highlight the structures and chemical moieties that are correlated with specific activity. As a result, the knowledge gained from the existing research should lead to the design and synthesis ofinnovative and multitargetedcurcumin analogues, derivatives, or curcumin hybrids, which would be very useful drug and tools in medicine for both diagnosis and treatment of AD.