scholarly journals Neurodegenerative Pathways in Alzheimer’s Disease: A Review

2020 ◽  
Vol 18 ◽  
Author(s):  
Anu K R ◽  
Subham Das ◽  
Alex Joseph ◽  
G Gautham Shenoy ◽  
Angel Treasa Alex ◽  
...  

: Alzheimer’s disease (AD) is a complex neurodegenerative disease which leads to insidious deterioration of brain function and is considered the sixth leading cause of death in the world. Alzheimer’s patients suffer from memory loss, cognitive deficit and behavioral changes; thus, they eventually follow a low-quality life. AD, considered as a multifactorial disorder involving different neuropathological mechanisms. Recent research has identified more than 20 pathological factors that are promoting disease progression. Three significant hypotheses are said to be the root cause of disease pathology, which include acetylcholine deficit, the formation of amyloid-beta senile plaques and tau protein hyperphosphorylation. Apart from these crucial factors, pathological factors such as apolipoprotein E (APOE), glycogen synthase kinase 3β, notch signaling pathway, Wnt signaling pathway, etc., are considered to play a role in the advancement of AD and therefore could be used as targets for drug discovery and development. As of today, there is no complete cure or effective disease altering therapies for AD. The current therapy is assuring only symptomatic relief from the disease, and progressive loss of efficacy for these symptomatic treatments warrants the discovery of newer drugs by exploring these novel drug targets. A comprehensive understanding of these therapeutic targets and their neuropathological role in AD is necessary to identify novel molecules for the treatment of AD rationally.

2017 ◽  
Vol 32 (7) ◽  
pp. 418-428 ◽  
Author(s):  
Ioana-Miruna Balmus ◽  
Alin Ciobica

Alzheimer’s disease leads to progressive cognitive function loss, which may impair both intellectual capacities and psychosocial aspects. Although the current knowledge points to a multifactorial character of Alzheimer’s disease, the most issued pathological hypothesis remains the cholinergic theory. The main animal model used in cholinergic theory research is the scopolamine-induced memory loss model. Although, in some cases, a temporary symptomatic relief can be obtained through targeting the cholinergic or glutamatergic neurotransmitter systems, no current treatment is able to stop or slow cognitive impairment. Many potentially successful therapies are often blocked by the blood–brain barrier since it exhibits permeability only for several classes of active molecules. However, the plant extracts’ active molecules are extremely diverse and heterogeneous regarding the biochemical structure. In this way, many active compounds constituting the recently tested plant extracts may exhibit the same general effect on acetylcholine pathway, but on different molecular ground, which can be successfully used in Alzheimer’s disease adjuvant therapy.


Author(s):  
Ashok K. Datusalia ◽  
Gurpreet Singh ◽  
Nikita Yadav ◽  
Sachin Gaun ◽  
Moumita Manik ◽  
...  

: Alzheimer’s disease (AD) is one of the most common neurodegenerative disease, which affect millions of people worldwide. Accumulation of amyloid-β plaques and hyperphosphorylated neurofibrillary tangles are the key mechanisms involved in the etiopathogenesis of AD, characterized by memory loss and behavioural changes. Effective therapies targeting AD pathogenesis are limited, making it the largest unmet clinical need. Unfortunately, the available drugs provide symptomatic relief and primary care, with no substantial impact on the disease pathology. However, in recent years researchers are working hard on several potential therapeutic targets to combat disease pathogenesis and few drugs have also reached clinical trials. In addition, drugs are being repurposed both in the preclinical and clinical studies for the treatment of AD. For instance, montelukast is most commonly used leukotriene receptor antagonist, for treating asthma and seasonal allergy. Its leukotriene antagonistic action can also be beneficial for the reduction of detrimental effects of leukotriene against neuro-inflammation, an hallmark feature of AD. The available marketed formulations of montelukast present challenges such as poor bioavailability and reduced uptake, reflecting the lack of effectiveness of its desired action in the CNS. While on the other side targeted drug delivery is a satisfactory approach to surpass the challenges associated with the therapeutic agents. This review will discuss the enhancement of montelukast treatment efficacy and its access to CNS, by using new approaches like nano-formulation, nasal gel, solid lipid formulation, nano-structure lipid carrier (NSLC), highlighting lessons learned to target AD pathologies and hurdles that persist.


Author(s):  
Xiao- Bei Zhang ◽  
Jintao Li ◽  
Juanhua Gu ◽  
Yue-Qin Zeng

: Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases with chronic, progressive, and irreversible characteristics, affecting nearly 50 million older adults worldwide. The pathogenesis of AD includes the formation of senile plaques, the abnormal aggregation of tau protein and the gradual degeneration and death of cerebral cortical cells. The main symptoms are memory loss, cognitive decline and behavioral disorders. Studies indicate that cannabidiol(CBD) possesses various pharmacological activities including anti-inflammatory, anti-oxidation and neuroprotective activities. It has been suggested as a potential multi-target medicine for treatment of AD. In this review, we aim to summarize the underlying mechanisms and protective effects of CBD on signaling pathways and central receptors involved in the pathogenesis of AD, including the endocannabinoid system(eCBs), the Transient receptor potential vanilloid type 1(TRPV1) receptor, and the Peroxisome proliferator-activated receptor (PPAR) receptor.


Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1267 ◽  
Author(s):  
Md. Sahab Uddin ◽  
Md. Tanvir Kabir ◽  
Kamal Niaz ◽  
Philippe Jeandet ◽  
Christophe Clément ◽  
...  

Alzheimer’s disease (AD) is one of the utmost chronic neurodegenerative disorders, which is characterized from a neuropathological point of view by the aggregates of amyloid beta (Aβ) peptides that are deposited as senile plaques and tau proteins which form neurofibrillary tangles (NFTs). Even though advancement has been observed in order to understand AD pathogenesis, currently available therapeutic methods can only deliver modest symptomatic relief. Interestingly, naturally occurring dietary flavonoids have gained substantial attention due to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties as alternative candidates for AD therapy. Experimental proof provides support to the idea that some flavonoids might protect AD by interfering with the production and aggregation of Aβ peptides and/or decreasing the aggregation of tau. Flavonoids have the ability to promote clearance of Aβ peptides and inhibit tau phosphorylation by the mTOR/autophagy signaling pathway. Moreover, due to their cholinesterase inhibitory potential, flavonoids can represent promising symptomatic anti-Alzheimer agents. Several processes have been suggested for the aptitude of flavonoids to slow down the advancement or to avert the onset of Alzheimer’s pathogenesis. To enhance cognitive performance and to prevent the onset and progress of AD, the interaction of flavonoids with various signaling pathways is proposed to exert their therapeutic potential. Therefore, this review elaborates on the probable therapeutic approaches of flavonoids aimed at averting or slowing the progression of the AD pathogenesis.


2020 ◽  
Vol 21 (5) ◽  
pp. 1746 ◽  
Author(s):  
Ana I. Duarte ◽  
Emanuel Candeias ◽  
Inês N. Alves ◽  
Débora Mena ◽  
Daniela F. Silva ◽  
...  

Alzheimer’s disease (AD) is the most common form of dementia worldwide, being characterized by the deposition of senile plaques, neurofibrillary tangles (enriched in the amyloid beta (Aβ) peptide and hyperphosphorylated tau (p-tau), respectively) and memory loss. Aging, type 2 diabetes (T2D) and female sex (especially after menopause) are risk factors for AD, but their crosslinking mechanisms remain unclear. Most clinical trials targeting AD neuropathology failed and it remains incurable. However, evidence suggests that effective anti-T2D drugs, such as the GLP-1 mimetic and neuroprotector liraglutide, can be also efficient against AD. Thus, we aimed to study the benefits of a peripheral liraglutide treatment in AD female mice. We used blood and brain cortical lysates from 10-month-old 3xTg-AD female mice, treated for 28 days with liraglutide (0.2 mg/kg, once/day) to evaluate parameters affected in AD (e.g., Aβ and p-tau, motor and cognitive function, glucose metabolism, inflammation and oxidative/nitrosative stress). Despite the limited signs of cognitive changes in mature female mice, liraglutide only reduced their cortical Aβ1–42 levels. Liraglutide partially attenuated brain estradiol and GLP-1 and activated PKA levels, oxidative/nitrosative stress and inflammation in these AD female mice. Our results support the earlier use of liraglutide as a potential preventive/therapeutic agent against the accumulation of the first neuropathological features of AD in females.


2020 ◽  
Vol 21 (5) ◽  
pp. 433-444 ◽  
Author(s):  
Vivek Kumar Sharma ◽  
Thakur Gurjeet Singh

Alzheimer’s disease (AD) is a chronic intensifying incurable progressive disease leading to neurological deterioration manifested as impairment of memory and executive brain functioning affecting the physical ability like intellectual brilliance, common sense in patients. The recent therapeutic approach in Alzheimer's disease is only the symptomatic relief further emerging the need for therapeutic strategies to be targeted in managing the underlying silent killing progression of dreaded pathology. Therefore, the current research direction is focused on identifying the molecular mechanisms leading to the evolution of the understanding of the neuropathology of Alzheimer's disease. The resultant saturation in the area of current targets (amyloid β, τ Protein, oxidative stress etc.) has led the scientific community to rethink of the mechanistic neurodegenerative pathways and reprogram the current research directions. Although, the role of stress has been recognized for many years and contributing to the development of cognitive impairment, the area of stress has got the much-needed impetus recently and is being recognized as a modifiable menace for AD. Stress is an unavoidable human experience that can be resolved and normalized but chronic activation of stress pathways unsettle the physiological status. Chronic stress mediated activation of neuroendocrine stimulation is generally linked to a high risk of developing AD. Chronic stress-driven physiological dysregulation and hypercortisolemia intermingle at the neuronal level and leads to functional (hypometabolism, excitotoxicity, inflammation) and anatomical remodeling of the brain architecture (senile plaques, τ tangles, hippocampal atrophy, retraction of spines) ending with severe cognitive deterioration. The present review is an effort to collect the most pertinent evidence that support chronic stress as a realistic and modifiable therapeutic earmark for AD and to advocate glucocorticoid receptors as therapeutic interventions.


2019 ◽  
Vol 16 (5) ◽  
pp. 418-452 ◽  
Author(s):  
Lídia Pinheiro ◽  
Célia Faustino

Alzheimer’s disease (AD) is a neurodegenerative disorder linked to protein misfolding and aggregation. AD is pathologically characterized by senile plaques formed by extracellular Amyloid-β (Aβ) peptide and Intracellular Neurofibrillary Tangles (NFT) formed by hyperphosphorylated tau protein. Extensive synaptic loss and neuronal degeneration are responsible for memory impairment, cognitive decline and behavioral dysfunctions typical of AD. Amyloidosis has been implicated in the depression of acetylcholine synthesis and release, overactivation of N-methyl-D-aspartate (NMDA) receptors and increased intracellular calcium levels that result in excitotoxic neuronal degeneration. Current drugs used in AD treatment are either cholinesterase inhibitors or NMDA receptor antagonists; however, they provide only symptomatic relief and do not alter the progression of the disease. Aβ is the product of Amyloid Precursor Protein (APP) processing after successive cleavage by β- and γ-secretases while APP proteolysis by α-secretase results in non-amyloidogenic products. According to the amyloid cascade hypothesis, Aβ dyshomeostasis results in the accumulation and aggregation of Aβ into soluble oligomers and insoluble fibrils. The former are synaptotoxic and can induce tau hyperphosphorylation while the latter deposit in senile plaques and elicit proinflammatory responses, contributing to oxidative stress, neuronal degeneration and neuroinflammation. Aβ-protein-targeted therapeutic strategies are thus a promising disease-modifying approach for the treatment and prevention of AD. This review summarizes recent findings on Aβ-protein targeted AD drugs, including β-secretase inhibitors, γ-secretase inhibitors and modulators, α-secretase activators, direct inhibitors of Aβ aggregation and immunotherapy targeting Aβ, focusing mainly on those currently under clinical trials.


2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Wenbin Wan ◽  
Shijin Xia ◽  
Bill Kalionis ◽  
Lumei Liu ◽  
Yaming Li

Accumulating evidence supports a key role for Wnt signaling in the development of the central nervous system (CNS) during embryonic development and in the regulation of the structure and function of the adult brain. Alzheimer’s disease (AD) is the most common form of senile dementia, which is characterized byβ-amyloid (Aβ) deposition in specific brain regions. However, the molecular mechanism underlying AD pathology remains elusive. Dysfunctional Wnt signaling is associated with several diseases such as epilepsy, cancer, metabolic disease, and AD. Increasing evidence suggests that downregulation of Wnt signaling, induced by Aβ, is associated with disease progression of AD. More importantly, persistent activation of Wnt signaling through Wnt ligands, or inhibition of negative regulators of Wnt signaling, such as Dickkopf-1 (DKK-1) and glycogen synthase kinase-3β(GSK-3β) that are hyperactive in the disease state, is able to protect against Aβtoxicity and ameliorate cognitive performance in AD. Together, these data suggest that Wnt signaling might be a potential therapeutic target of AD. Here, we review recent studies related to the progression of AD where Wnt signaling might be relevant and participate in the development of the disease. Then, we focus on the potential relevance of manipulating the Wnt signaling pathway for the treatment of AD.


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