Leukotriene receptor antagonist use and cognitive decline in normal cognition, mild cognitive impairment, and Alzheimer's dementia

Tetrazole derivatives in the management of neurological disorders: Recent advances on synthesis and pharmacological aspects

Neurological disorders are the leading cause of a large number of mortalities and morbidities. Nitrogen heterocyclic compounds have been pivotal in exhibiting wide array of therapeutic applications. Among them, tetrazole is a ubiquitous class of organic heterocyclic compounds that have attracted much attention because of its unique structural and chemical properties, and a wide range of pharmacological activities comprising anti-convulsant effect, antibiotic, anti-allergic, anti-hypertensive to name a few. Owing to significant chemical and biological properties, the present review aimed at highlighting the recent advances in tetrazole derivatives with special emphasis on their role in the management of neurological diseases. Besides, in-depth structure-activity relationships, molecular docking studies, and associated modes of action of tetrazole derivatives evident in in vitro, in vivo preclinical, and clinical studies have been discussed.

Montelukast Ameliorates 2K1C-Hypertension Induced Endothelial Dysfunction and Associated Vascular Dementia

BACKGROUND

Declined kidney function associated with hypertension is a danger for cognitive deficits, dementia, and brain injury. Cognitive decline and vascular dementia (VaD) are serious public health concerns, which highlights the urgent need for study on the risk factors for cognitive decline. Cysteinyl leukotriene (CysLT1) receptors are concerned with regulating cognition, motivation, inflammatory processes, and neurogenesis.

OBJECTIVE

This research aims to examine the consequence of montelukast (specific CysLT1 antagonist) in renovascular hypertension 2-kidney-1-clip-2K1C model-triggered VaD in experimental animals.

METHODS

2K1C tactics were made to prompt renovascular hypertension in mature male rats. Morris water maze was employed to measure cognition. Mean arterial pressure (MAP), serum nitrite levels, aortic superoxide content, vascular endothelial activity, brain's oxidative stress (diminished glutathione, raised lipid peroxides), inflammatory markers (IL-10, IL-6, TNF-α), cholinergic activity (raised acetylcholinesterase), and cerebral injury (staining of 2, 3, 5- triphenylterazolium chloride) were also examined.

RESULTS

Montelukast in doses of 5.0 and 10.0 mg kg-1 was used intraperitoneally as the treatment drug. Along with cognitive deficits, 2K1C-operated rats showed elevated MAP, endothelial dysfunction, brain oxidative stress, inflammation, and cerebral damage with diminished serum nitrite/nitrate. Montelukast therapy significantly and dose-dependently mitigated the 2K1Chypertension- provoked impaired behaviors, biochemistry, endothelial functions, and cerebral infarction.

CONCLUSION

The 2K1C tactic caused renovascular hypertension and associated VaD, which was mitigated via targeted regulation of CysLT1 receptors by montelukast administration. Therefore, montelukast may be taken into consideration for the evaluation of its complete potential in renovascular-hypertension-induced VaD.

Montelukast Ameliorates Scopolamine-induced Alzheimer's Disease: Role on Cholinergic Neurotransmission, Antioxidant Defence System, Neuroinflammation and Expression of BDNF

BACKGROUND

Alzheimer's disease (AD) is an overwhelming neurodegenerative disease with progressive loss of memory. AD is characterized by the deposition of the senile plaques mainly composed of β-amyloid (Aβ) fragment, BDNF decline, Cholinergic system overactivity and neuroinflammation. Montelukast (MTK), a leukotriene receptor antagonist, showed astounding neuroprotective effects in a variety of neurodegenerative disorders.

OBJECTIVE

This study aims to investigate the ameliorative effects of Montelukast in the scopolamineinduced Alzheimer's disease (AD) model in rats and evaluate its activity against neuroinflammation.

METHODS

Thirty rats were split into five groups: Control group (1 mL/kg normal saline, i.p.), Montelukast perse (10 mg/kg, i.p.), Disease group treated with Scopolamine (3 mg/kg, i.p.), Donepezil group (3 mg/kg, i.p.), Montelukast treatment group (10 mg/kg, i.p.) and behavioural and biochemical tests were carried out to assess the neuro protective effect.

RESULTS

Scopolamine treatment led to a significant reduction in learning and memory and an elevation in cholinesterase levels when compared with the control group (p < 0.01). Additionally, elevated oxidative stress and Amyloid-β levels were associated with enhanced neuroinflammation (p < 0.05, p < 0.01). Furthermore, the decline in neurotrophic factor BDNF is also observed when compared with the normal control group (p < 0.01). Montelukast pre-treatment significantly attenuated learning and memory impairment and cholinesterase levels. Besides, Montelukast and standard drug donepezil administration significantly suppressed the oxidative stress markers (p < 0.01), Amyloid-β levels, neuroinflammatory mediators (p < 0.05) and caused a significant increase in BDNF levels (p < 0.05).

CONCLUSION

Montelukast bestowed ameliorative effects in scopolamine-induced AD animal models as per the previous studies via attenuation of memory impairment, cholinesterase neurotransmission, oxidative stress, Amyloid-β levels, neuroinflammatory mediators and enhanced BDNF levels.

Alzheimer's genes in microglia: a risk worth investigating

Despite expressing many key risk genes, the role of microglia in late-onset Alzheimer's disease pathophysiology is somewhat ambiguous, with various phenotypes reported to be either harmful or protective. Herein, we review some key findings from clinical and animal model investigations, discussing the role of microglial genetics in mediating perturbations from homeostasis. We note that impairment to protective phenotypes may include prolonged or insufficient microglial activation, resulting in dysregulated metabolomic (notably lipid-related) processes, compounded by age-related inflexibility in dynamic responses. Insufficiencies of mouse genetics and aggressive transgenic modelling imply severe limitations in applying current methodologies for aetiological investigations. Despite the shortcomings, widely used amyloidosis and tauopathy models of the disease have proven invaluable in dissecting microglial functional responses to AD pathophysiology. Some recent advances have brought modelling tools closer to human genetics, increasing the validity of both aetiological and translational endeavours.

Neuropsychiatric events associated with montelukast in patients with asthma: a systematic review

BACKGROUND

The United States Food and Drug Administration issued a black box warning on the mental health adverse effects of montelukast in 2020. Age-related effects on the risk of developing specific neuropsychiatric events in montelukast users remain largely unknown.

OBJECTIVE

To describe the risk of neuropsychiatric events associated with montelukast in adults and children with asthma.

METHODS

A systematic search of all studies investigating neuropsychiatric events in montelukast users was performed in PubMed, the Cochrane Library and Embase from inception to 7 September 2022. Animal studies and conference abstracts were excluded.

RESULTS

59 studies (21 pharmacovigilance studies, four reviews from 172 randomised controlled trials, 20 observational studies, 10 case reports and four case series) evaluating neuropsychiatric events in patients with asthma on montelukast were reviewed. No significant association was shown between montelukast and suicide-related events in six of the observational studies. No association was found for depression as defined by the International Classification of Diseases 10th revision codes in three observational studies and a review of randomised clinical trials. However, findings from four studies using antidepressant prescriptions as the outcome identified significant associations. Consistent with nine pharmacovigilance studies, two large-scale observational studies revealed possible associations of montelukast with anxiety and sleeping disorders in adult patients with asthma, respectively. However, the results were not replicated in two observational studies on children.

CONCLUSION

Montelukast is not associated with suicide- and depression-related events in asthma patients. Older adults may be particularly susceptible to anxiety and sleeping disorders.

Lipid Mediated Brain Disorders: A Perspective

The brain, one of the most resilient organs of the body is highly enriched in lipid content, suggesting the essential role of lipids in brain physiological activities. Lipids constitute an important structural part of the brain and act as a rich source of metabolic energy. Besides, lipids in their bioactive form (known as bioactive lipids) play an essential signaling and regulatory role, facilitating neurogenesis, synaptogenesis, and cell-cell communication. Brain lipid metabolism is thus a tightly regulated process. Any alteration/dysregulation of lipid metabolism greatly impact brain health and activity. Moreover, since central nervous system (CNS) is the most metabolically active system and lacks an efficient antioxidative defence system, it acts as a hub for the production of reactive oxygen species (ROS) and subsequent lipid peroxidation. These peroxidation events are reported during pathological changes such as neuronal tissue injury and inflammation. Present review is a modest attempt to gain insights into the role of dysregulated bioactive lipid levels and lipid oxidation status in the pathogenesis and progression of neurodegenerative disorders. This may open up new avenues exploiting lipids as the therapeutic targets for improving brain health, and treatment of nervous system disorders.

Leukotrienes in Innate Immunity: Still Underappreciated after All These Years?

Leukotrienes (LTs) are lipid mediators derived from the 5-lipoxygenase pathway of arachidonate metabolism. Though best known for their role in asthma, they have broad actions that touch on virtually every aspect of mammalian biology. In a Brief Review published in the journal in 2005, we presented the existing evidence supporting a role for LTs in host defense. In this updated Brief Review, we focus on selected advances since then. We detail new insights into mechanisms and regulation of LT biosynthesis; the protective roles of LTs in the host response to diverse classes of pathogens, with an emphasis on viruses, including SARS-CoV-2; the phagocyte signal transduction mechanisms by which LTs exert their antimicrobial actions; the capacity for overexuberant LT production to promote tissue damage; and roles of LTs in the noninfectious immune-relevant conditions neuroinflammation and cancer.

Synaptic degeneration in Alzheimer disease

Alzheimer disease (AD) is characterized by progressive cognitive decline in older individuals accompanied by the presence of two pathological protein aggregates - amyloid-β and phosphorylated tau - in the brain. The disease results in brain atrophy caused by neuronal loss and synapse degeneration. Synaptic loss strongly correlates with cognitive decline in both humans and animal models of AD. Indeed, evidence suggests that soluble forms of amyloid-β and tau can cause synaptotoxicity and spread through neural circuits. These pathological changes are accompanied by an altered phenotype in the glial cells of the brain - one hypothesis is that glia excessively ingest synapses and modulate the trans-synaptic spread of pathology. To date, effective therapies for the treatment or prevention of AD are lacking, but understanding how synaptic degeneration occurs will be essential for the development of new interventions. Here, we highlight the mechanisms through which synapses degenerate in the AD brain, and discuss key questions that still need to be answered. We also cover the ways in which our understanding of the mechanisms of synaptic degeneration is leading to new therapeutic approaches for AD.

Age-linked suppression of lipoxin A4 associates with cognitive deficits in mice and humans

Age increases the risk for cognitive impairment and is the single major risk factor for Alzheimer's disease (AD), the most prevalent form of dementia in the elderly. The pathophysiological processes triggered by aging that render the brain vulnerable to dementia involve, at least in part, changes in inflammatory mediators. Here we show that lipoxin A4 (LXA4), a lipid mediator of inflammation resolution known to stimulate endocannabinoid signaling in the brain, is reduced in the aging central nervous system. We demonstrate that genetic suppression of 5-lipoxygenase (5-LOX), the enzyme mediating LXA4 synthesis, promotes learning impairment in mice. Conversely, administration of exogenous LXA4 attenuated cytokine production and memory loss induced by inflammation in mice. We further show that cerebrospinal fluid LXA4 is reduced in patients with dementia and positively associated with cognitive performance, brain-derived neurotrophic factor (BDNF), and AD-linked amyloid-β. Our findings suggest that reduced LXA4 levels may lead to vulnerability to age-related cognitive disorders and that promoting LXA4 signaling may comprise an effective strategy to prevent early cognitive decline in AD.

Relationship between urinary dichlorophenols and cognitive function among people over 60 years old from NHANES

Studies have shown that exposure to dichlorophenols (DCPs) and their precursors might have potential neurotoxicity, which may be related to low cognitive function, but there are few large-scale, representative population data to explore the association between DCP exposure and cognitive function. We aimed to examine the relationship between urinary DCPs and cognitive function in the US older people. A total of 952 participants ≥ 60 years old from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2011-2014) were enrolled. The Consortium to Establish a Registry for Alzheimer's disease Word Learning subtest (CERAD W-L), the Animal Fluency test (AFT), and the Digit Symbol Substitution test (DSST) were used to assess cognition. Multivariate logistic regression and restricted cubic spline (RCS) were used to evaluate the relationship between DCP exposure and cognitive function. A positive association between 2,5-DCP and the risk of bad performance of DSST was observed (P for trend = 0.024) after adjusting for the covariates. Compared to the lowest quartile, OR of DSST for the highest quartile of 2,5-DCP was 1.72 (95%CI:1.03-2.87, P = 0.039). There were no significant associations between DCPs and the other tests. The RCS plot showed an inverted J-shaped relationship between 2,5-DCP, 2,4-DCP, and the DSST score. The inflection points for the curves were found at 1.531 μg/L and 0.230 μg/L, respectively. On the right side of the inflection points, the DSST score dropped sharply. In subgroup analysis, those under 70 years old, smokers, and alcohol drinkers had a higher risk of bad performance in DSST when exposed to 2,5-DCP. The higher concentration of urinary DCPs is associated with a lower score of DSST in the US older people.

Exploring the inverse association of glioblastoma multiforme and Alzheimer's disease via bioinformatics analysis

Glioblastoma multiforme (GBM) and Alzheimer's disease (AD) are two major diseases in the nervous system with a similar peak age of onset, which has the typical characteristics of high cost, difficult treatment, and poor prognosis. Epidemiological studies and a few molecular biological studies have hinted at an opposite relationship between AD and GBM. However, there are few studies on their reverse relationship, and the regulatory mechanism is still unclear, indicating that further systematic research is urgently needed. Our study firstly employs advanced bioinformatics methods to explore the inverse relationship between them and find various target drugs. We obtained the gene expression dataset from public databases (GEO, TCGA, and GTEx). Then, we identified 122 differentially expressed genes (DEGs) of AD and GBM. Four significant gene modules were identified through protein-protein interaction (PPI) and module construction, and 13 hub genes were found using cytoHubba. We constructed co-expression networks and found various target drugs through these hub genes. Functional enrichment analysis revealed that the AMPK pathway, cell cycle, and cellular senescence play important roles in AD and GBM. Our study may provide a potential direction for studying the opposite molecular mechanism of AD and GBM in the future.

Design of Montelukast Nanocrystalline Suspension for Parenteral Prolonged Delivery

Background

Montelukast (MTK), a representative leukotriene receptor antagonist, is currently being investigated as a potential candidate for treating Alzheimer’s disease. For potent and effective dosing in elderly patients, a parenteral prolonged delivery system is favored, with improved medication adherence with reduced dosage frequency.

Purpose

This study aimed to design a nanocrystalline suspension (NS)-based MTK prolonged delivery system and evaluate its pharmacokinetics profile and local tolerability following subcutaneous administration.

Methods

To decelerate the dissolution rate, the amorphous MTK raw material was transformed into a crystalline state using a solvent-mediated transformation method and subsequently formulated into NS using a bead-milling technique. The MTK NSs were characterized by morphology, particle size, crystallinity, and in vitro dissolution profiles. The pharmacokinetic profile and local tolerability at the injection site following subcutaneous injection of MTK suspension were evaluated in rats.

Results

Microscopic and physical characterization revealed that the amorphous MTK powder was lucratively transformed into a crystalline form in acidic media (pH 4). MTK crystalline suspensions with different diameters (200 nm, 500 nm, and 3 μm) were uniformly prepared using bead-milling technology, employing polysorbate 80 as suspending agent. Prepared crystalline suspensions exhibited analogous crystallinity (melting point, 150°C) and size-dependent in vitro dissolution profiles. MTK NSs with particle sizes of 200 nm and 500 nm provided a protracted pharmacokinetic profile for up to 4 weeks in rats, with a higher maximum drug concentration in plasma than the 3 μm-sized injectable suspensions. Histopathological examination revealed that MTK NS caused chronic granulomatous inflammation at the injection site, which resolved after 4 weeks.

Conclusion

The MTK parenteral NS delivery system is expected to be a valuable tool for treating Alzheimer’s disease with extended dose intervals.

Computational Analysis of Pathogenetic Pathways in Alzheimer’s Disease and Prediction of Potential Therapeutic Drugs

Background. Alzheimer’s disease (AD) is a chronic and progressive neurodegenerative disease which affects more than 50 million patients and represents 60–80% of all cases of dementia. Mutations in the APP gene, mostly affecting the γ-secretase site of cleavage and presenilin mutations, have been identified in inherited forms of AD. Methods. In the present study, we performed a meta-analysis of the transcriptional signatures that characterize two familial AD mutations (APP^V7171F and PSEN1^M146V) in order to characterize the common altered biomolecular pathways affected by these mutations. Next, an anti-signature perturbation analysis was performed using the AD meta-signature and the drug meta-signatures obtained from the L1000 database, using cosine similarity as distance metrics. Results. Overall, the meta-analysis identified 1479 differentially expressed genes (DEGs), 684 downregulated genes, and 795 upregulated genes. Additionally, we found 14 drugs with a significant anti-similarity to the AD signature, with the top five drugs being naftifine, moricizine, ketoconazole, perindopril, and fexofenadine. Conclusions. This study aimed to integrate the transcriptional profiles associated with common familial AD mutations in neurons in order to characterize the pathogenetic mechanisms involved in AD and to find more effective drugs for AD.