Umuhengerin Neuroprotective Effects in Streptozotocin-Induced Alzheimer's Disease Mouse Model via Targeting Nrf2 and NF-Kβ Signaling Cascades

Prophylactic effects of apigenin against hyperglycemia-associated amnesia via activation of the Nrf2/ARE pathway in zebrafish

The escalating focus on ageing-associated disease has generated substantial interest in the phenomenon of cognitive impairment linked to diabetes. Hyperglycemia exacerbates oxidative stress, contributes to β-amyloid accumulation, disrupts mitochondrial function, and impairs cognitive function. Existing therapies have certain limitations, and apigenin (AG), a natural plant flavonoid, has piqued interest due to its antioxidant, anti-inflammatory, and anti-hyperglycemic properties. So, we anticipate that AG might be a preventive medicine for hyperglycemia-associated amnesia. To test our hypothesis, naïve zebrafish were trained to acquire memory and pretreated with AG. Streptozotocin (STZ) was administered to mimic hyperglycemia-induced memory dysfunction. Spatial memory was assessed by T-maze and object recognition through visual stimuli. Acetylcholinesterase (AChE) activity, antioxidant enzyme status, and neuroinflammatory genes were measured, and histopathology was performed in the brain to elucidate the neuroprotective mechanism. AG exhibits a prophylactic effect and improves spatial learning and discriminative memory of STZ-induced amnesia in zebrafish under hyperglycemic conditions. AG also reduces blood glucose levels, brain oxidative stress, and AChE activity, enhancing cholinergic neurotransmission. AG prevented neuronal damage by regulating brain antioxidant response elements (ARE), collectively contributing to neuroprotective properties. AG demonstrates a promising effect in alleviating memory dysfunction and mitigating pathological changes via activation of the Nrf2/ARE mechanism. These findings underscore the therapeutic potential of AG in addressing memory dysfunction and neurodegenerative changes associated with hyperglycemia.

Canagliflozin Mitigated Cognitive Impairment in Streptozotocin-Induced Sporadic Alzheimer's Disease in Mice: Role of AMPK/SIRT-1 Signaling Pathway in Modulating Neuroinflammation

Sporadic Alzheimer's disease (SAD) represents a major health concern especially among elderly. Noteworthy, neuroinflammation and oxidative stress are highly implicated in AD pathogenesis resulting in enhanced disease progression. Moreover, most of the available anti-Alzheimer drugs have several adverse effects with variable efficacy, therefore new strategies, including agents with anti-inflammatory and antioxidant effects, are encouraged. Along these lines, canagliflozin (CAN), with its anti-inflammatory and anti-apoptotic activities, presents a promising candidate for AD treatment. Therefore, this study aimed to evaluate the therapeutic potential of CAN via regulation of AMPK/SIRT-1/BDNF/GSK-3β signaling pathway in SAD. SAD model was induced by intracerebroventricular streptozotocin injection (ICV-STZ;3 mg/kg, once), while CAN was administered (10 mg/kg/day, orally) to STZ-treated mice for 21 days. Behavioral tests, novel object recognition (NOR), Y-Maze, and Morris Water Maze (MWM) tests, histopathological examination, total adenosine monophosphate-activated protein kinase (T-AMPK) expression, p-AMPK, and silent information regulator-1 (SIRT-1) were evaluated. Furthermore, brain-derived neurotrophic factor (BDNF), glycogen synthase kinase-3β (GSK-3β), acetylcholinesterase (AChE), Tau protein, insulin-degrading enzyme (IDE), nuclear factor erythroid-2 (Nrf-2), interleukin-6 (IL-6), nuclear factor kappa-B-p65 (NFκB-p65), beta-site APP cleaving enzyme 1 (BACE-1), and amyloid beta (Aβ) plaque were assessed. CAN restored STZ-induced cognitive deficits, confirmed by improved behavioral tests and histopathological examination. Besides, CAN halted STZ-induced neurotoxicity through activation of p-AMPK/SIRT-1/BDNF pathway, subsequently reduction of GSK-3β, Tau protein, AChE, NFκB-p65, IL-6, BACE-1, and Aβ plaque associated with increased IDE and Nrf-2. Consequentially, our findings assumed that CAN, via targeting p-AMPK/SIRT-1 pathway, combated neuroinflammation and oxidative stress in STZ-induced AD. Thus, this study highlighted the promising effect of CAN for treating AD.

The protective effect of biotin supplementation and swimming training on cognitive impairment and mental symptoms in a rat model of Alzheimer's disease: A behavioral, biochemical, and histological study

Vitamin B (Vit B) plays a regulatory role in cognitive memory and learning. We examined the biochemical and behavioral effects of biotin supplementation (BS) and swimming training (ST) on Alzheimer's disease (AD), the most common type of dementia, in male rats. Sixty rats were randomly assigned to six groups: control, sham (receiving phosphate-buffered saline), AD (receiving a single injection of Aβ into the lateral ventricle), ST (for 28 days and before Aβ injection), and BS (receiving BS through oral gavage for 28 days before Aβ injection). The treatments were continued until the end of the behavioral tests. Learning and memory functions were investigated through the Morris water maze (MWM) and depression and anxiety-like behaviors were tested by elevated plus-maze (EPM) and forced swimming tests. In addition, oxidative stress biomarkers, such as total thiol groups (TTG) and malondialdehyde (MDA) in serum were assessed and histological studies were performed using brain tissues. In the AD group, Aβ increased the distance traveled and escape latency in the MWM, but co-administration of BS and ST attenuated the results of the MWM, EPM, and FST tests. Furthermore, BS decreased the litigious biochemical effects of Aβ by enhancing the levels of TTG, in addition to reducing serum MDA levels. The use of BS as a potent antioxidant improved Aβ-induced memory impairment. It attenuated oxidative stress biomarkers in the brain (number of Aβ plaques) and serum of AD rats. We provide evidence for the use of BS in neurodegenerative disorders, such as AD, to elucidate the possible mechanisms.

α-Glucosidase, butyrylcholinesterase and acetylcholinesterase inhibitory activities of phenolic compounds from Carthamus tinctorius L. flowers: In silico and in vitro studies

Chemical investigation of Carthamus tinctorius L. flowers resulted in isolation of seven metabolites that were identified as; p-Hydroxybenzoic acid (1), trans hydroxy cinnamic acid (2), kaempferol-6-C-glucoside (3), astragalin (4), cartormin (5), kaempferol-3-O-rutinoside (6), and kaempferol-3-O-sophoroside (7). Virtual screening of the isolated compounds against human intestinal α-glucosidase, acetylcholinesterase, and butyrylcholinesterase was carried out. Additionally, the antioxidant activity of the bioactive compounds was assessed. Compounds 1 and 5 exhibited moderate binding affinities to acetylcholinesterase (binding energy -5.33 and -4.18 kcal/mol, respectively), compared to donepezil (-83.33kcal/mol). Compounds 1-7 demonstrated weak affinity to butyrylcholinesterase. Compounds 2 and 4 displayed moderate binding affinity to human intestinal α-glucosidase,compared to Acarbose (reference compound), meanwhile compound 2 exhibited lower affinity. Molecular dynamic studies revealed that compound 4 formed a stable complex with the binding site throughout a 100 ns simulation period. The in-vitro results were consistent with the virtual experimental results, as compounds 1 and 5 showed mild inhibitory effects on acetylcholinesterase (IC50s 150.6 and 168.7 µM, respectively). Compound 4 exhibited moderate α-glucosidase inhibition with an IC50 of 93.71 µM. The bioactive compounds also demonstrated notable antioxidant activity in ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)], ORAC (oxygen radical-absorbance capacity), and metal chelation assays, suggesting their potential in improving dementia in Alzheimer's disease (AD) and mitigating hyperglycemia.

Beneficial effect of lupeol and metformin in mouse model of intracerebroventricular streptozotocin induced dementia

This study examines the effectiveness of lupeol and metformin in a mouse model of dementia generated by intracerebroventricular streptozotocin (i.c.v., STZ). Dementia was induced in Swiss mice with the i.c.v. administration of STZ at a dosage of 3 mg/kg on the first and third day. The assessment of dementia involved an examination of the Morris Water Maze (MWM) performance, as well as a number of biochemical and histological studies. STZ treatment resulted in significant decrease in MWM performance; various biochemical alterations (increase in brain acetyl cholinesterase (AChE) activity, thiobarbituric acid reactive species (TBARS), nitrite/nitrate, and reduction in nuclear factor erythroid 2 related factor-2 (Nrf-2), reduced glutathione (GSH) levels) and neuroinflammation [increased myeloperoxidase (MPO) activity & neutrophil infiltration]. The administration of Lupeol (50 mg/kg & 100 mg/kg; p.o.) and Metformin (150 mg/kg & 300 mg/kg; p.o.) demonstrated a considerable reduction in the behavioral, biochemical, and histological alterations produced by STZ. Low dose combination of lupeol (50 mg/kg; p.o.) and Metformin (150 mg/kg; p.o.) produced more pronounced effect than that of high doses of either agent alone. It is concluded that Lupeol and Metformin has shown efficacy in dementia with possible synergism between the two and can be explored as potential therapeutic agents for managing dementia of Alzheimer's disease (AD) type.

Intranasal Administration of Apelin-13 Ameliorates Cognitive Deficit in Streptozotocin-Induced Alzheimer's Disease Model via Enhancement of Nrf2-HO1 Pathways

BACKGROUND

The discovery of novel diagnostic methods and therapies for Alzheimer's disease (AD) faces significant challenges. Previous research has shed light on the neuroprotective properties of Apelin-13 in neurodegenerative disorders. However, elucidating the mechanism underlying its efficacy in combating AD-related nerve injury is imperative. In this study, we aimed to investigate Apelin-13's mechanism of action in an in vivo model of AD induced by streptozocin (STZ).

METHODS

We utilized an STZ-induced nerve injury model of AD in mice to investigate the effects of Apelin-13 administration. Apelin-13 was administered intranasally, and cognitive impairment was assessed using standardized behavioral tests, primarily, behavioral assessment, histological analysis, and biochemical assays, in order to evaluate synaptic plasticity and oxidative stress signaling pathways.

RESULTS

Our findings indicate that intranasal administration of Apelin-13 ameliorated cognitive impairment in the STZ-induced AD model. Furthermore, we observed that this effect was potentially mediated by the enhancement of synaptic plasticity and the attenuation of oxidative stress signaling pathways.

CONCLUSIONS

The results of this study suggest that intranasal administration of Apelin-13 holds promise as a therapeutic strategy for preventing neurodegenerative diseases such as AD. By improving synaptic plasticity and mitigating oxidative stress, Apelin-13 may offer a novel approach to neuroprotection in AD and related conditions.

Discovery of anti-inflammatory natural flavonoids: Diverse scaffolds and promising leads for drug discovery

Natural products have been utilized for medicinal purposes for millennia, endowing them with a rich source of chemical scaffolds and pharmacological leads for drug discovery. Among the vast array of natural products, flavonoids represent a prominent class, renowned for their diverse biological activities and promising therapeutic advantages. Notably, their anti-inflammatory properties have positioned them as promising lead compounds for developing novel drugs combating various inflammatory diseases. This review presents a comprehensive overview of flavonoids, highlighting their manifold anti-inflammatory activities and elucidating the underlying pathways in mediating inflammation. Furthermore, this review encompasses systematical classification of flavonoids, related anti-inflammatory targets, involved in vitro and in vivo test models, and detailed statistical analysis. We hope this review will provide researchers engaged in active natural products and anti-inflammatory drug discovery with practical information and potential leads.

Natural antioxidants that act against Alzheimer's disease through modulation of the NRF2 pathway: a focus on their molecular mechanisms of action

Characterized by a complex pathophysiology that includes the intraneuronal formation of neurofibrillary tangles and the extracellular deposition of β-amyloid plaques, Alzheimer's disease (AD) is a terminal neurodegenerative disease that causes dementia in older adults. Oxidative stress in the brain is considered as one of the contributing factors to the pathogenesis of AD, and thus, antioxidants have attracted much interest as potential therapeutic agents against the disorder. Natural antioxidants are typically characterized by low acute and chronic toxicity, which facilitates their potential therapeutic application. One important molecular target for the beneficial effects of natural antioxidants is the nuclear factor erythroid-derived 2-related factor 2 (NFE2L2/NRF2). NRF2 is a key transcription factor that orchestrates the cellular antioxidant response through regulating the expression of oxidative stress-related genes harboring the antioxidant response element (ARE) in their promoters. Indeed, in the case of excessive oxidative damage, NRF2 migrates to the nucleus and binds to ARE, activating the transcription of antioxidant protector genes. There is increasing evidence that NRF2 is implicated in AD pathology through dysfunction and altered localization, which renders it as a potential therapeutic target for AD. Thus, this review summarizes the most recent (2018-2023) advances on the NRF2-modulating activity of natural antioxidants observed in vitro and in AD animal models. This information will help elucidate the molecular mechanisms governing the antioxidant activity of such phytochemicals to highlight their therapeutic potential against common neurodegenerative diseases, such as AD.

Intermittent theta burst stimulation attenuates oxidative stress and reactive astrogliosis in the streptozotocin-induced model of Alzheimer's disease-like pathology

Introduction

Intracerebroventricularly (icv) injected streptozotocin (STZ) is a widely used model for sporadic Alzheimer's disease (sAD)-like pathology, marked by oxidative stress-mediated pathological progression. Intermittent theta burst stimulation (iTBS) is a noninvasive technique for brain activity stimulation with the ability to induce long-term potentiation-like plasticity and represents a promising treatment for several neurological diseases, including AD. The present study aims to investigate the effect of the iTBS protocol on the animal model of STZ-induced sAD-like pathology in the context of antioxidant, anti-inflammatory, and anti-amyloidogenic effects in the cortex, striatum, hippocampus, and cerebellum.

Methods

Male Wistar rats were divided into four experimental groups: control (icv normal saline solution), STZ (icv STZ-3 mg/kg), STZ + iTBS (STZ rats subjected to iTBS protocol), and STZ + Placebo (STZ animals subjected to placebo iTBS noise artifact). Biochemical assays and immunofluorescence microscopy were used to evaluate functional and structural changes.

Results

The icv STZ administration induces oxidative stress and attenuates antioxidative capacity in all examined brain regions. iTBS treatment significantly reduced oxidative and nitrosative stress parameters. Also, iTBS decreased Aβ-_1-42 and APP levels. The iTBS enhances antioxidative capacity reported as elevated activity of its enzymatic and non-enzymatic components. In addition, iTBS elevated BDNF expression and attenuated STZ-induced astrogliosis confirmed by decreased GFAP⁺/VIM⁺/C3⁺ cell reactivity in the hippocampus.

Discussion

Our results provide experimental evidence for the beneficial effects of the applied iTBS protocol in attenuating oxidative stress, increasing antioxidant capacity and decreasing reactive astrogliosis in STZ-administrated rats.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

Andrographolide Attenuates Short-Term Spatial and Recognition Memory Impairment and Neuroinflammation Induced by a Streptozotocin Rat Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder clinically manifested by a gradual cognitive decline. Intracerebroventricular injection (ICV) of streptozotocin (STZ), a model of sporadic AD (sAD), shows many aspects of sAD abnormalities (i.e., neuroinflammation, oxidative stress, protein aggregation), resulting in memory impairment. Andrographolide (ANDRO), a natural diterpene lactone, has numerous bioactivities including anti-inflammatory and antioxidant properties. Studies in rodents revealed that ANDRO has neuroprotective properties and restores cognitive impairment. In the present study, we investigated the effects of ANDRO in the ICV-STZ model relative to short-term spatial memory (object location test (OLT) and Y maze test), short-term recognition memory (object recognition test (ORT)), locomotor activity (open field test (OFT)), expression of amyloid precursor protein (APP), and activation of astrocytes (glial fibrillary acidic protein (GFAP) expression) and microglia (ionized calcium-binding adapter molecule-1 (Iba-1) immunohistochemistry) in the prefrontal cortex (PFC) and hippocampus (HIP). Wistar rats were injected ICV with STZ (3 mg/kg) or vehicle and treated with ANDRO (2 mg/kg, i.p.; three times per week). After four weeks, ANDRO attenuated the impairments of the Y maze and ORT performances, and the increase of astrocyte activation in the PFC induced by the ICV-STZ model. In addition, ANDRO decreased the number of activated microglia cells in the HIP of STZ-injected rats. The APP expression was not altered, neither by the STZ nor ANDRO. ANDRO showed a beneficial effect on memory impairment and neuroinflammation in the STZ model of AD.