Chronic oral exposure of aluminum chloride in rat modulates molecular and functional neurotoxic markers relevant to Alzheimer's disease

Betulinic acid protects against lipopolysaccharide and ferrous sulfate-induced oxidative stress, ferroptosis, apoptosis, and neuroinflammation signaling relevant to Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the selective degeneration of dopaminergic neurons in the substantia nigra, leading to profound motor dysfunction and non-motor symptoms.

OBJECTIVES

Despite significant advancements in understanding PD pathophysiology, effective disease-modifying therapies remain elusive. Current research efforts are increasingly focused on developing and refining advanced in-vivo models to unravel PD mechanisms and explore novel therapeutic interventions. In this study, we investigated the neuroprotective potential of Betulinic acid (BA), a natural triterpenoid, in an experimental model of PD.

MATERIAL AND METHODS

We evaluated the amelioration of motor impairments and associated pathological alterations in Wistar rats. The experimental model involved the administration of lipopolysaccharide (LPS) and ferrous sulfate (FeSO4). BA was administered orally to evaluate its potential neuroprotective effects.

RESULTS

Our findings demonstrated that BA administration significantly reversed behavioral deficits and mitigated molecular, immunohistopathological, and biochemical abnormalities in LPS + FeSO4-induced PD model. Notably, BA treatment restored levels of tyrosine hydroxylase (TH) and reduced alpha-synuclein (α-syn) accumulation, both of which were significantly altered in this model. These neuroprotective effects were accompanied by a reduction in oxidative stress, ferroptosis, and apoptosis biomarkers implicated in neurodegeneration.

SUMMARY

These results collectively suggested that α-syn aggregation, ferroptosis, and apoptotic cell death are the critical contributors to PD pathology and highlighted Betulinic acid as a promising therapeutic candidate for combating neurodegeneration in PD. These findings may open new avenues for developing pharmacological agents targeting the complex mechanisms of PD.

Isoliensinine ameliorates cognitive dysfunction in AlCl3/D-gal-induced Alzheimer's disease-like mice by inhibiting the calcium signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The embryos of lotus (Nelumbo nucifera Gaertn.) is a famous traditional Chinese medicine used to treat insomnia, memory decline, and dementia for a long time. However, the underlying material basis and mechanisms of this medicine are still unclear. Isoliensinine (IL) is a major alkaloid derived from lotus embryos. Our previous research has demonstrated that IL can exert strong anti-inflammatory and neuroprotective effects in vitro.

AIM OF THE STUDY

To reveal the underlying therapeutic effect and mechanism of IL on Alzheimer's disease (AD)-like mice induced by AlCl3 and D-galactose (D-gal) in vivo.

MATERIALS AND METHODS

The AD-like mice were modeled by intragastric injection (i.g.) of AlCl3 (20 mg/kg/day) and intraperitoneal injection (i.p.) of D-gal (120 mg/kg/day) for 8 weeks. Starting from the third week, AD-like mice were treated with IL (1, 3, or 10 mg/kg/day; i.p.) for 6 weeks. Cognitive impairment in AD-like mice was evaluated through some behavioral experiments including nest building, open field, novel object recognition, Y maze, and Morris water maze tests. The cortex and hippocampus (DG, CA1, and CA3) regions were analyzed as follows: Neuronal pathological changes and neurofibrillary tangles (NFTs) formation were observed by hematoxylin-eosin (HE) and silver staining, respectively; The production of Aβ plaques and the activation of microglia and astrocytes were detected by immunohistochemistry; The levels of Ca2+ levels were determined by the ortho-cresolphtalein complexone method. The levels of inflammatory cytokines (TNF-α, IL-6, and IL-1β) were analyzed using the ELISA kits. The expression of CaM, p-CaMKII, Calpain, CDK5, p35/p25, p-Tau, ADAM10, BACE1, PSEN1, APP, Aβ1-42, p-IκBα, and IκBα were evaluated by western blotting.

RESULTS

IL (1, 3, and 10 mg/kg) treatment effectively ameliorated cognitive impairment in AD-like model mice. IL inhibited the decrease of brain index and body weight in AD-like mice and alleviated neuronal damage in the cortex and hippocampus (DG, CA1, and CA3). IL decreased the levels of Ca2+ and reduce high expression of CaM and Calpain in the cortex and hippocampus of AD-like mice. IL treatment did not affect the expression of CDK5 but inhibited the expression of p-CaMKII and p25/p35, and reduced Tau phosphorylation and NFTs formation. IL also down-regulated the high expression of Aβ1-42 and APP and regulated the expression of APP-cleavage secretase (reducing the expression of BACE1 and PSEN1, while increasing the expression of ADAM10), thereby inhibited the production of Aβ plaques in AD-like mouse brain. Moreover, IL inhibited the phosphorylation and degradation of IκBα, as well as the production of inflammatory cytokines (TNF-α, IL-6, and IL-1β), and prevented the activation of microglia and astrocytes in AD-like mice.

CONCLUSIONS

IL has a significant therapeutic effect on pathological alterations and cognitive impairment in AlCl3 and D-gal-induced AD-like mice, indicating that IL may have the potential to treat AD. The anti-AD activity of IL may be associated with its regulation of the Ca2+ homeostasis and downstream signaling molecules such as CaM and Calpain.

Neochlorogenic acid ameliorates Alzheimer's disease-like pathology via scavenging oxidative stress and restoring blood-brain barrier function in zebrafish

Alzheimer's disease is the most widespread neurodegenerative disease characterized by insidious onset and slow progression. At present, most available medications serve to attenuate the progression of Alzheimer's disease with side effects and drug resistance. Neochlorogenic acid is a natural polyphenolic compound with excellent antioxidant properties. Based on zebrafish Alzheimer's disease model induced by AlCl3, we found that neochlorogenic acid significantly improved motor dysfunction, reduced brain cell apoptosis, and Aβ plaque. Because of antioxidant stress and improvement of blood-brain barrier dysfunction are important in treating Alzheimer's disease, we explored the interaction between these two mechanisms in alleviating the pathological course of Alzheimer's disease. Neochlorogenic acid inhibited the overproduction of reactive oxygen species, suppressed the gene expression encoding antioxidant-related proteins, and protected brain cell integrity while enhancing Nrf2, improving blood-brain barrier nerve resilience. Meanwhile, neochlorogenic acid attenuated blood-brain barrier dysfunction in Alzheimer's disease zebrafish by reducing blood hemoglobin leakage and upregulating the gene expression encoding blood-brain barrier endothelial cell-related proteins, resulting in reactive oxygen species in a controllable state. In conclusion, our research suggests that neochlorogenic acid ameliorates Alzheimer's disease-like pathology by inhibiting oxidative stress and restoring blood-brain barrier function, indicating that neochlorogenic acid may be a potential drug for treating Alzheimer's disease.

Therapeutic potential of chrysin in regulation of interleukin-17 signaling in a repeated intranasal amyloid-beta-induced Alzheimer's disease model

Objective: The aim of the current study was to study the therapeutic potential of chrysin against repeated intranasal amyloid-beta (Aβ)-induced interleukin-17 (IL-17) signaling in a mouse model of AD. Methods: Male BALB/c mice were daily exposed to intranasal Aβ1-42 (10 μg/10 μL) for seven consecutive days. Chrysin was orally administered at doses of 25, 50 and 100 mg kg-1 in 0.5% sodium carboxy methyl cellulose suspension from day 5 of Aβ1-42 administration for seven days. Following the treatment, the memory of the animals was appraised using Morris water maze, novel object recognition and passive avoidance tests. Further, the effects of chrysin on Aβ1-42-induced IL-17 signaling and redox levels were evaluated in the cortex and hippocampus regions of the mouse brain through western blot and immunohistochemistry. Results: The exposure to Aβ1-42 through the intranasal route induced a significant decline in the spatial, learning and cognitive memory of the animals, and most interestingly, exposure to Aβ1-42 triggered IL-17-mediated signaling, which resulted in a significant increase in the expression of IL-17RA, Act1 and TRAF6. Furthermore, Aβ1-42 impaired the tissue redox level and inflammatory cytokines in the mouse brain. Alternatively, treatment with chrysin at 25, 50 and 100 mg kg-1 oral doses alleviated Aβ1-42-mediated memory decline, impaired redox levels and inflammation. Specifically, chrysin downregulated the expression of IL-17 and mediated signaling in the brain regions of the mice. Conclusion: Chrysin was evidenced to be a potent antioxidant and anti-inflammatory agent, clearly showing a protective role against Aβ1-42-induced IL-17-mediated inflammation in the brain of the mice.

Aluminum chloride and D-galactose induced a zebrafish model of Alzheimer's disease with cognitive deficits and aging

Alzheimer's disease (AD) is an age-related neurodegenerative disorder. Transgenic and pharmacological AD models are extensively studied to understand AD mechanisms and drug discovery. However, they are time-consuming and relatively costly, which hinders the discovery of potential anti-AD therapeutics. Here, we established a new model of AD in larval zebrafish by co-treatment with aluminum chloride (AlCl3) and D-galactose (D-gal) for 72 h. In particular, exposure to 150 μM AlCl3 + 40 mg/mL D-gal, 200 μM AlCl3 + 30 mg/mL D-gal, or 200 μM AlCl3 + 40 mg/mL D-gal successfully induced AD-like symptoms and aging features. Co-treatment with AlCl3 and D-gal caused significant learning and memory deficits, as well as impaired response ability and locomotor capacity in the plus-maze and light/dark test. Moreover, increased acetylcholinesterase and β-galactosidase activities, β-amyloid 1-42 deposition, reduced telomerase activity, elevated interleukin 1 beta mRNA expression, and enhanced reactive oxygen species production were also observed. In conclusion, our zebrafish model is simple, rapid, effective and affordable, incorporating key features of AD and aging, thus may become a unique and powerful tool for high-throughput screening of anti-AD compounds in vivo.

Phikud navakot extract acts as an ER stress inhibitor to ameliorate ER stress and neuroinflammation

The prevalence of neurological disorders (NDs) such as Alzheimer's disease (AD) is increasing globally, and the lack of effective pharmacological interventions presents a significant health risk. Multiple mechanisms including the activation of oxidative stress, amyloid pathway, ER stress, and neuroinflammation have been implicated in AD; therefore, multi-targeted agents against these mechanisms may be preferable to single-target agents. Phikud Navakot (PN), a Thai traditional medicine combining nine herbs, has been shown to reduce oxidative stress and neuroinflammation of neuronal and microglia cells and the coculture between them, indicating the promising role of PN extract as anti-AD. This study evaluated the neuroprotective effects of PN extract against oxidative stress, amyloid pathway, endoplasmic reticulum stress (ER stress), and neuroinflammation using neuronal and microglia cells, as well as in a Drosophila model of AD. Results showed that PN extract reduced oxidative stress, lipid peroxidation, pro-inflammatory cytokines, amyloid pathway, and ER stress induced by aluminum chloride (AlCl3, AD-induced agent) or thapsigargin (TG, an ER stress activator) in both neurons and microglia cells. PN extract also reduced oxidative stress, ER-stress-related genes, and neurotoxic peptides (amyloid beta) in a Drosophila model of AD. Data indicated that PN extract may function as an anti-AD agent by targeting multiple mechanisms as described. This research also revealed for the first time that PN extract acted as an ER stress inhibitor.

Sweet basil (Ocimum basilicum) leaf and seed extracts alleviate neuronal dysfunction in aluminum chloride-induced neurotoxicity in Drosophila melanogaster Meigen model

Ocimum basilicum is an important medicinal plant and culinary herb generally known as sweet basil (SB). These plants are effective radical scavengers, that have been employed in treatment of nervous system disorders, and thus, could be beneficial for the management of neurodegenerative diseases (NDs). Current clinical treatments for NDs present several side effects, therefore, there is need to develop new treatments that can mitigate these deadly diseases. Hence, this study investigated the neuroprotective activities of SB leaf and seed in aluminum chloride (AlCl3)-induced toxicity in Drosophila melanogaster. HPLC characterization of the leaves and seeds were carried out. AlCl3-diet was used to induce neurodegeneration and treated flies received SB leaf and seed extracts-supplemented diet. Survival and locomotor performance activities/levels of oxidative biomarkers [reactive oxygen species (ROS), thiobarbituric acid reactive species (TBARS), total thiol, catalase, superoxide dismutase (SOD) and glutathione-S-transferase (GST)], enzymes linked with neurodegeneration (acetylcholinesterase (AChE) and monoamine oxidase (MAO)) were investigated. SB leaf had significantly (p < 0.05) higher polyphenol contents; gallic acid and P-coumaric acid were the most abundant polyphenol in the leaf and seed respectively. Percentage survival and locomotor rates, level/activities of total thiol, catalase, SOD and GST were significantly (p < 0.05) reduced while ROS, TBARS, AChE and MAO activities were significantly (p < 0.05) increased in AlCl3-diet-fed flies. Treatment with SB leaf and seed diet lessened these observed impairments. However, SB leaf had better neuroprotective activities that could be related to the observed higher phenolic constituents. Hence, SB leaf diet may offer improved therapeutic effect in NDs.

Neuroprotective effect of taxifolin against aluminum chloride-induced dementia and pathological alterations in the brain of rats: possible involvement of toll-like receptor 4

Aluminum (Al) overexposure damages various organ systems, especially the nervous system. Regularly administered aluminum chloride (AlCl3) to rats causes dementia and pathophysiological alterations linked to Alzheimer's disease (AD). Taxifolin's neuroprotective effects against AlCl3-induced neurotoxicity in vitro and in vivo studies were studied. Taxifolin (0.1, 0.3, 1, 3, and 10 μM) was tested against AlCl3 (5 mM)-induced neurotoxicity in C6 and SH-SY5Y cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Additionally, neural morphology was examined by confocal microscopy. Additionally, taxifolin's mode of binding with the co-receptor of toll-like receptor 4 (TLR4), human myeloid differentiation-2 (hMD-2) was investigated. AlCl3 (25 mg/kg/d, i.p.) was administered to rats for 14 d, and from the eighth day, taxifolin (1, 2, and 5 mg/kg/d, i.p.) was given along with AlCl3. This study assessed memory impairment using the Morris water maze, plus maze, and pole tests. This study also performed measurement of oxidant (malondialdehyde [MDA] and nitrite), antioxidant (reduced glutathione), and inflammatory (myeloperoxidase [MPO] activity, TLR4 expression) parameters in rats' brain in addition to histopathology. The docking score for taxifolin with hMD-2 was found to be -4.38 kcal/mol. Taxifolin treatment reduced the neurotoxicity brought on by AlCl3 in both C6 and SH-SY5Y cells. Treatment with 10 μM taxifolin restored AlCl3-induced altered cell morphology. AlCl3 administration caused memory loss, oxidative stress, inflammation (increased MPO activity and TLR4 expression), and brain atrophy. Taxifolin treatment significantly improved the AlCl3-induced memory impairment. Taxifolin treatment also mitigated the histopathological and neurochemical consequences of repeated AlCl3 administration in rats. Thus, taxifolin may protect the brain against AD.

Docosahexaenoic Acid (DHA), Vitamin D3, and Probiotics Supplementation Improve Memory, Glial Reactivity, and Oxidative Stress Biomarkers in an Aluminum-Induced Cognitive Impairment Rat Model

Globally, the rise in neurodegenerative issues in tandem with shifts in lifestyle and aging population has prompted a search for effective interventions. Nutraceutical compounds have emerged as promising agents for addressing these challenges. This 60-day study on an aluminum-induced cognitive impairment rat model assessed three compounds and their combinations: probiotics (Prob, Lactobacillus plantarum [5 × 1010 CFU/day], and Lactobacillus acidophilus [5 × 1010 CFU/day]), docosahexaenoic acid (DHA, 23.8 mg/day), and vitamin D3 (VD3, 150 IU/day). Behavioral outcomes were evaluated by using the Morris water maze and novel object recognition tests. Glial activation was assessed through immunofluorescence analysis of GFAP/Iba1, and oxidative stress markers in brain tissue were determined by measuring the levels of Malondialdehyde (MDA) and Superoxide dismutase (SOD). The results demonstrated a progressive improvement in the learning and memory capacity. The aluminum group exhibited the poorest performance in the behavioral test, enhanced GFAP/Iba1 activation, and elevated levels of oxidative stress markers. Conversely, the DHA + Prob + VD3 treatment demonstrated the best performance in the Morris water maze. The combination of DHA + Prob + VD3 exhibited superior performance in the Morris water maze, accompanied by reduced levels of GFAP/Iba1 activation in DG/CA1 brain regions. Furthermore, DHA + Prob supplementation showed lower GFAP/Iba1 activation in the CA3 region and enhanced antioxidant activity. In summary, supplementing various nutraceutical combinations, including DHA, VD3, and Prob, displayed notable benefits against aluminum-induced cognitive impairment. These benefits encompassed memory enhancement, diminished MDA concentration, increased SOD activity, and reduced glial activation, as indicated by GFAP/Iba1 markers.

Protective effect of a hydromethanolic extract from Fraxinus excelsior L. bark against a rat model of aluminum chloride-induced Alzheimer's disease: Relevance to its anti-inflammatory and antioxidant effects

ETHNOPHARMACOLOGICAL RELEVANCE

Fraxinus excelsior L. (FE), commonly known as the ash, belongs to the Oleaceae family and has shown several pharmacological and biological properties, such as antioxidant, immunomodulatory, neuroprotective, and anti-inflammatory effects. It has also attracted the most attention toward neuroinflammation. Moreover, FE bark and leaves have been used to treat neurological disorders, aging, neuropathic pain, urinary complaints, and articular pain in traditional and ethnomedicine. Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder resulting from the involvement of amyloid-beta, metal-induced oxidative stress, and neuroinflammation.

AIM OF THE STUDY

The objective of the current study was to assess the neuroprotective effects of hydromethanolic extract from FE bark in an AlCl3-induced rat model of AD.

MATERIALS AND METHODS

The maceration process was utilized to prepare the hydromethanolic extract of FE bark, and characterized by LC-MS/MS. To assess the anti-AD effects of the FE extract, rats were categorized into five different groups, AlCl3; normal control; FE-treated groups at 50, 100, and 200 mg/kg. Passive avoidance learning test, Y-maze, open field, and elevated plus maze behavioral tests were evaluated on days 7 and 14 to analyze the cognitive impairments. Zymography analysis, biochemical tests, and histopathological changes were also followed in different groups.

RESULTS

LC-MS/MS analysis indicated the presence of coumarins, including isofraxidin7-O-diglucoside in the methanolic extract of FE as a new isofraxidin derivative in this genus. FE significantly improved memory and cognitive function, maintained weight, prevented neuronal damages, and preserved the hippocampus's histological features, as demonstrated by behavioral tests and histopathological analysis. FE increased anti-inflammatory MMP-2 activity, whereas it decreased that of inflammatory MMP-9. Moreover, FE increased plasma antioxidant capacity by enhancing CAT and GSH while decreasing nitrite levels in the serum of treated groups. In comparison between the treated groups, the rats that received high doses of the FE extract (200 mg/kg) showed the highest therapeutic effect.

CONCLUSION

FE rich in coumarins could be an effective anti-AD adjunct agent, passing through antioxidant and anti-inflammatory pathways. These results encourage further studies for the development of this extract as a promising agent in preventing, managing, or treating AD and related diseases.

Dauricine alleviates cognitive impairment in Alzheimer's disease mice induced by D-galactose and AlCl3 via the Ca2+/CaM pathway

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly. Dysregulation of intracellular Ca2+ homeostasis plays a critical role in the pathological development of AD. Dauricine (DAU) is a bisbenzylisoquinoline alkaloid isolated from Menispermum dauricum DC., which can prevent the influx of extracellular Ca2+ and inhibit the release of Ca2+ from the endoplasmic reticulum. DAU has a potential for anti-AD. However, it is unclear whether DAU can exert its anti-AD effect in vivo by regulating the Ca2+ related signaling pathways. Here, we investigated the effect and mechanism of DAU on D-galactose and AlCl3 combined-induced AD mice based on the Ca2+/CaM pathway. The results showed that DAU (1 mg/kg and 10 mg/kg for 30 days) treatment attenuated learning and memory deficits and improved the nesting ability of AD mice. The HE staining assay showed that DAU could inhibit the histopathological alterations and attenuate neuronal damage in the hippocampus and cortex of AD mice. Studies on the mechanism indicated that DAU decreased the phosphorylation of CaMKII and Tau and reduced the formation of NFTs in the hippocampus and cortex. DAU treatment also reduced the abnormally high expression of APP, BACE1, and Aβ1-42, which inhibited the deposition of Aβ plaques. Moreover, DAU could decrease Ca2+ levels and inhibit elevated CaM protein expression in the hippocampus and cortex of AD mice. The molecular docking results showed that DAU may have a high affinity with CaM or BACE1. DAU has a beneficial impact on pathological changes in AD mice induced by D-galactose and AlCl3 and may act by negative regulation of the Ca2+/CaM pathway and its downstream molecules such as CaMKII and BACE1.

A new “turn-on” molecular switch for idiosyncratic detection of Al3+ ion along with its application in live cell imaging

A new highly sensitive, reversible, reusable and fluorogenic “turn-on” switch (HBTC) has been fabricated for the sole detection of Al3+.