Aluminum-Induced Cognitive Impairment and PI3K/Akt/mTOR Signaling Pathway Involvement in Occupational Aluminum Workers

The mechanism of miR-665 targeting GNB3 in aluminum-induced neuronal apoptosis

BACKGROUND

Aluminum exerts neurotoxic effects through various mechanisms, mainly manifested as impaired learning and memory function.

METHODS

Forty SD rats were divided into 0, 10, 20, and 40 mM maltol aluminum [Al(mal)3] groups. Cell experiments are divided into 0, 100, 200, and 400 μM Al(mal)3 dose group and control, Al(mal)3, Al(mal)3+inhibitor NC, Al(mal)3+miR-665 inhibitor intervention group. Water maze was used to detect the learning and memory function of rats, HE staining was used to observe the morphology and number of neurons in the CA1 area of the rat hippocampus, Flow cytometry was used to detect the apoptosis of PC12 cells, PCR and Western blotting were used to detect the expression of Caspase3, miR-665 and GNB3/PI3K/AKT proteins. The target binding relationship between miR-665 and GNB3 was verified by double luciferase reporter gene experiment.

RESULTS

In vivo experimental results showed that with the increase of Al(mal)3 concentration, the escape latency of rats was prolonged, the target quadrant dwell time was shortened, and the number of crossing platform was reduced. Moreover, the arrangement of neurons was loose and the number decreased; the expression of Caspase3 and miR-665 increased, while the expression of GNB3/PI3K/AKT proteins decreased. In vitro experiments, with the increase of Al(mal)3 concentration, apoptosis rate of PC12 cells increased, the expression of Caspase3, miR-665 and GNB3/PI3K/AKT proteins were consistent with rat results. After inhibiting miR-665 in the intervention group experiment, apoptosis rate of PC12 cells in the aluminum exposure group decreased, the expression of Caspase3 and miR-665 decreased, and the expression of GNB3/PI3K/AKT proteins increased.

CONCLUSION

MiR-665 plays an important role in aluminum induced neuronal apoptosis by targeting GNB3 and regulating the PI3K/AKT pathway.

Exploring the Combined Effect of Exercise and Apigenin on Aluminium-Induced Neurotoxicity in Zebrafish

Aluminium (AL) is a strong environmental neurotoxin linked to neurodegenerative disorders. Widespread industrial use leads to its presence in water systems, causing bioaccumulation in organisms. This, in turn, results in the bioaccumulation of AL in various organisms. Several studies have highlighted the benefits of enhanced physical activity in combating neurodegenerative diseases. Meanwhile widespread presence of apigenin in aquatic environment has been largely overlooked, in terms of its potential to counter AL-induced neurotoxicity. The combined impact of exercise and apigenin in mitigating the effects of AL-induced neurotoxicity in aquatic animals remains unexplored. Hence, the objective of this study is to determine whether the combined treatment of exercise and apigenin can effectively alleviate the chronic neurotoxicity induced by AL. Zebrafish that were exposed to AL showed behaviours resembling anxiety, increased aggression, unusual swimming pattern, and memory impairment, which are typical features observed in Alzheimer's disease (AD)-like syndrome. Combined treatment of exercise and apigenin protects zebrafish from AL-induced neurotoxicity, which was measured by improvements in memory, reduced anxiety and aggression, and increased levels of antioxidant enzymes and acetylcholinesterase (AChE) activity. Furthermore, AL exposure is associated with increased expression of genes related to neuroinflammation and AD. However, synergistic effect of exercise and apigenin counteract this effect in AL-treated zebrafish. These findings suggest that AL is involved in neurodegenerative diseases in fish, which could affect the integrity of aquatic ecosystem. Hence, there is a strong correlation between enhanced physical activity, apigenin, and the well-being of the ecosystem.

Decoupling of gray and white matter functional networks in cognitive impairment induced by occupational aluminum exposure

Aluminum (Al) is a low-toxic, accumulative substance with neurotoxicity properties that adversely affect human cognitive function. This study aimed to investigate the neurobiological mechanisms underlying cognitive impairment resulting from occupational Al exposure. Resting-state functional magnetic resonance imaging was conducted on 54 individuals with over 10 years of Al exposure. Al levels were measured, and cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). Subsequently, the K-means clustering algorithm was employed to identify functional gray matter (GM) and white matter (WM) networks. Two-sample t-tests were conducted between the cognition impairment group and the control group. Al exhibited a negative correlation with MoCA scores. Participants with cognitive impairment demonstrated reduced functional connectivity (FC) between the middle cingulum network (WM1) and anterior cingulum network (WM2), as well as between the executive control network (WM6) and limbic network (WM10). Notably, decreased FCs were observed between the executive control network (GM5) and WM1, WM4, WM6, and WM10. Additionally, the FC of GM5-GM4 and WM1-WM2 negatively correlated with Trail Making Test Part A (TMT-A) scores. Prolonged Al accumulation detrimentally affects cognition, primarily attributable to executive control and limbic network disruptions.

Zinc as a Mediator Through the ROCK1 Pathway of Cognitive Impairment in Aluminum-Exposed Workers: A Clinical and Animal Study

Aluminum (Al) exposure was implicated in neurodegenerative diseases and cognitive impairment, yet the involvement of zinc (Zn) and its mechanism in Al-induced mild cognitive impairment (MCI) remains poorly understood. The objective is to explore the role of Zn in Al-induced cognitive impairment and its potential mechanisms. Montreal cognitive assessment (MoCA) test scores and serum Al, Zn from Al industry workers were collected. A mediation analysis was performed to evaluate the role of serum Zn among serum Al and MoCA test scores. Subsequently, an Al-exposure study was conducted on a rat model categorized into control, low-, medium-, and high-dose groups. After a Morris Water Maze test and detection of Al, Zn content in the hippocampus, integrated transcriptomic and proteomic analyses between the control group and the high-dose group were performed to identify the differentially expressed genes (DEPs), proteins (DEPs), and pathways. To corroborate these findings, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting (WB) were selected to identify the gene and protein results. Zn overall mediates the relationship between serum Al and cognitive function (mediation effect 17.82%, effect value =  - 0.0351). In the Al-exposed rat model, 734 DEGs, 18 miRNAs, 35 lncRNAs, 64 circRNAs, and 113 DEPs were identified between the high-dose group and the control group. Among them, ROCK1, DMD, and other four DEPs were identified as related to zinc finger proteins (ZNF). Co-enrichment analyses of the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) linked these changes to the RHOA/ROCK1 signaling axis. ZNF-related proteins Rock1, DMD, and DHX57 in the high-dose group were downregulated (p = 0.006, 0.003, 0.04), and the expression of Myl9, Rhoa, miR431, and miR182 was also downregulated (p = 0.003, 0.032, 0.032, and 0.046). These findings also show correlations between Al, Zn levels in the hippocampus, water maze performance, and expressions of Myl9, Rhoa, miR431, miR182, DMD, ROCK1, and DHX57, with both negative and positive associations. Based on the results, we determined that Zn was involved in Al-induced MCI in Al workers and Al-exposed rat models. Al exposure and interaction with Zn could trigger the downregulation of ZNF of ROCK1, DMD, and DHX57. miR431, miR182 regulate RHOA/ROCK1 was one of the Zn-involved pathways in Al-induced cognitive impairment.

Selenium alleviates modafinil-induced neurobehavioral toxicity in rat via PI3K/Akt/mTOR/GSK3B signaling pathway and suppression of oxidative stress and apoptosis: in vivo and in silico study

Nonmedical use of modafinil (MOD) led to increased rates of overdose toxicity, road accidents, addiction, withdrawal, suicide, and mental illnesses. The current study aims to determine the probable MOD brain toxicity and elucidate the possible role of selenium (Se) in ameliorating the neurotoxicity in rat models. Fifty-four male Albino rats were randomly assigned into nine groups. The groups were G1 (control negative), G2 (Se0.1), G3 (Se0.2), G4 (MOD300), G5 (MOD600), G6 (Se0.1 + MOD300), G7 (Se0.2 + MOD300), G8 (Se0.1 + MOD600), and G9 (Se0.2 + MOD600). After finishing the experiment, blood and brain tissue were harvested for biochemical and histological investigation. Neurobehavior parameters were assessed. Tissue neurotransmitter levels and oxidative stress markers were assessed. Gene expression of PI3K/Akt/mTOR-GSK3B, orexin, and orexin receptor2 was measured by qRT-PCR. Histological and immunohistochemistry assessments, as well as molecular docking, were carried out. MOD-induced neurobehavioral toxicity exhibited by behavioral and cognitive function impairments, which are associated with decreased antioxidant activities, increased MDA levels, and decreases in neurotransmitter levels. Brain levels of mRNA expression of PI3K, Akt, and mTOR were decreased, while GS3K, orexin, and orexin receptors were significantly elevated. These disturbances were confirmed by histopathological brain changes with increased silver and Bax immunostaining and decreased crystal violet levels. MOD induced neurotoxic effects in a dose-dependent manner. Compared with the MOD groups, SE coadministration significantly attenuates MOD-induced toxic changes. Docking study shows the protective role of Se as an apoptosis inhibitor and inflammation inhibitor. In conclusion, Se could be used as a biologically effective antioxidant compound to protect from MOD neurobehavioral toxicity in Wistar rats by reversing behavioral alterations, inflammation, apoptosis, and oxidative injury.

Aluminum exposure induces central nervous system impairment via activating NLRP3-medicated pyroptosis pathway

PURPOSE

Aluminum is an environmental toxicant whose long-term exposure is closely associated with nervous system impairment. This study mainly investigated neurological impairment induced by subchronic aluminum exposure via activating NLRP3-medicated pyroptosis pathway.

METHODS

In vivo, Kunming mice were exposed to AlCl3 (30.3 mg/kg, 101 mg/kg and 303 mg/kg) via drinking water for 3 months, and administered with Rsv (100 mg/kg) by gavage for 1 month. Cognitive impairment was assessed by Morris water maze test, and pathological injury was detected via H&E staining. BBB integrity, pyroptosis and neuroinflammation were evaluated through western blotting and immunofluorescence methods. In vitro, BV2 microglia was treated with AlCl3 (0.5 mM, 1 mM and 2 mM) to sensitize pyroptosis pathway. The protein interaction was verified by co-immunoprecipitation, and neuronal damage was estimated via a conditioned medium co-culture system with BV2 and TH22 cells.

RESULTS

Our results showed that AlCl3 induced mice memory disorder, BBB destruction, and pathological injury. Besides, aluminum caused glial activation, sensitized DDX3X-NLRP3 pyroptosis pathway, released cytokines IL-1β and IL-18, initiating neuroinflammation. BV2 microglia treated with AlCl3 emerged hyperactivation and pyroptotic death, and Ddx3x knockdown inhibited pyroptosis signaling pathway. DDX3X acted as a live-or-die checkpoint in stressed cells by regulating NLRP3 inflammasome and G3BP1 stress granules. Furthermore, aluminum-activated microglia had an adverse effect on co-cultured neurons and destroyed nervous system homeostasis.

CONCLUSION

Aluminum exposure could induce pyroptosis and neurotoxicity. DDX3X determined live or die via selectively regulating pro-survival stress granules or pro-death NLRP3 inflammasome. Excessive activation of microglia might damage neurons and aggravate nerve injury.

In vitro evaluation of the cytotoxic and genotoxic effects of Al and Mn in ambient concentrations detected in groundwater intended for human consumption

Environmental exposure to metals can induce cytotoxic and genotoxic effects in cells and affect the health of the exposed population. To investigate the effects of aluminum (Al) and manganese (Mn), we evaluated their cytogenotoxicity using peripheral blood mononuclear cells (PBMCs) exposed to these metals at previously quantified concentrations in groundwater intended for human consumption. The cell viability, membrane integrity, nuclear division index (NDI), oxidative stress, cell death, cell cycle, and DNA damage were analyzed in PBMCs exposed to Al (0.2, 0.6, and 0.8 mg/L) and Mn (0.1, 0.3, 1.0, and 1.5 for 48 h. We found that Al induced late apoptosis; decreased cell viability, NDI, membrane integrity; and increased DNA damage. However, no significant alterations in the early apoptosis, cell cycle, and reactive oxygen species levels were observed. In contrast, exposure to Mn altered all evaluated parameters related to cytogenotoxicity. Our data show that even concentrations allowed by the Brazilian legislation for Al and Mn in groundwater intended for human consumption cause cytotoxic and genotoxic effects in PBMCs. Therefore, in view of the results found, a comprehensive approach through in vivo investigations is needed to give robustness and validity to the results obtained, thus broadening the understanding of the impacts of metals on the health of environmentally exposed people.

Recent insights into autophagy and metals/nanoparticles exposure

Some anthropogenic pollutants, such as heavy metals and nanoparticles (NPs), are widely distributed and a major threat to environmental safety and public health. In particular, lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and mercury (Hg) have systemic toxicity even at extremely low concentrations, so they are listed as priority metals in relation to their significant public health burden. Aluminum (Al) is also toxic to multiple organs and is linked to Alzheimer's disease. As the utilization of many metal nanoparticles (MNPs) gradually gain traction in industrial and medical applications, they are increasingly being investigated to address potential toxicity by impairing certain biological barriers. The dominant toxic mechanism of these metals and MNPs is the induction of oxidative stress, which subsequently triggers lipid peroxidation, protein modification, and DNA damage. Notably, a growing body of research has revealed the linkage between dysregulated autophagy and some diseases, including neurodegenerative diseases and cancers. Among them, some metals or metal mixtures can act as environmental stimuli and disturb basal autophagic activity, which has an underlying adverse health effect. Some studies also revealed that specific autophagy inhibitors or activators could modify the abnormal autophagic flux attributed to continuous exposure to metals. In this review, we have gathered recent data about the contribution of the autophagy/mitophagy mediated toxic effects and focused on the involvement of some key regulatory factors of autophagic signaling during exposure to selected metals, metal mixtures, as well as MNPs in the real world. Besides this, we summarized the potential significance of interactions between autophagy and excessive reactive oxygen species (ROS)-mediated oxidative damage in the regulation of cell survival response to metals/NPs. A critical view is given on the application of autophagy activators/inhibitors to modulate the systematic toxicity of various metals/MNPs.

Improvement in Zebrafish with Diabetes and Alzheimer's Disease Treated with Pasteurized Akkermansia muciniphila

Diabetes and Alzheimer's disease (AD) are associated with specific changes in the composition of the intestinal flora. Studies have shown that the supplementation with pasteurized Akkermansia muciniphila has therapeutic and preventive effects on diabetes. However, it is not clear whether there is any association with improvement in and prevention of Alzheimer's disease and diabetes with Alzheimer's disease. Here, we found that pasteurized Akkermansia muciniphila can significantly improve the blood glucose, body mass index, and diabetes indexes of zebrafish with diabetes mellitus complicated with Alzheimer's disease and also alleviate the related indexes of Alzheimer's disease. The memory, anxiety, aggression, and social preference behavior of zebrafish with combined type 2 diabetes mellitus (T2DM) and Alzheimer's disease (TA zebrafish) were significantly improved after pasteurized Akkermansia muciniphila treatment. Moreover, we examined the preventive effect of pasteurized Akkermansia muciniphila on diabetes mellitus complicated with Alzheimer's disease. The results showed that the zebrafish in the prevention group were better in terms of biochemical index and behavior than the zebrafish in the treatment group. These findings provide new ideas for the prevention and treatment of diabetes mellitus complicated with Alzheimer's disease. IMPORTANCE The interaction between intestinal microflora and host affects the progression of diabetes and Alzheimer's disease. As a recognized next-generation probiotic, Akkermansia muciniphila has been shown to play a key role in the progression of diabetes and Alzheimer's disease, but whether A. muciniphila can improve diabetes complicated with Alzheimer's disease and its potential mechanism are unclear. In this study, a new zebrafish model of diabetes mellitus complicated with Alzheimer's disease was established, and the effect of Akkermansia muciniphila on diabetes mellitus complicated with Alzheimer's disease is discussed. The results showed that Akkermansia muciniphila after pasteurization significantly improved and prevented diabetes mellitus complicated with Alzheimer's disease. Treatment with pasteurized Akkermansia muciniphila improved the memory, social preference, and aggressive and anxiety behavior of TA zebrafish and alleviated the pathological characteristics of T2DM and AD. These results provide a new prospect for probiotics in the treatment of diabetes and Alzheimer's disease.

Simultaneous effects of aluminum exposure on the homeostasis of essential metal content in rat brain and perturbation of gut microbiota

The theory of the brain-gut axis has confirmed that gut microbiota and metabolites are involved in the progression of neurodegenerative diseases through multiple pathways. However, few studies have highlighted the role of gut microbiota in cognitive impairment induced by aluminum (Al) exposure and its correlations with the homeostasis of essential metal content in the brain. To explore the relationship between alterations in the content of essential metals in the brain and relative abundance changes in gut microbiota induced by Al exposure, the Al, zinc (Zn), copper (Cu), iron (Fe), chromium (Cr), manganese (Mn), and cobalt (Co) content level in the hippocampus, olfactory bulb, and midbrain tissue were measured by inductively coupled plasma mass spectrometry (ICP-MS) methods after Al maltolate was intraperitoneally injected every other day for exposed groups. Then the unsupervised principal coordinates analysis (PCoA) and linear discriminant analysis effect size (LEfSe) were used to analyze the relative abundance of the gut microbiota community and the structure of the gut microbiome. Finally, the correlations between gut microbiota composition and essential metal content in the different exposure groups were explored by using the Pearson correlation coefficient method. Based on the results, we indicated that the content of Al in the hippocampus, olfactory bulb, and midbrain tissue was increased and then decreased with the increasing exposure duration, with peaks occurring between 14 and 30 days. Concomitantly, Al-exposure decreased the Zn, Fe, and Mn levels in these tissues. 16 S rRNA gene sequencing results indicated that significant differences in the intestinal microbial community structure at the phylum, family, and genus levels were found in the Day 90 exposed group compared with the Day 7 exposed group. Ten enriched species in the exposed group were identified as markers at the three levels. Furthermore, ten bacteria at the genus level were identified to have a significantly strong correlation (r = 0.70-0.90) with Fe, Zn, Mn, and Co.

Aluminum neurotoxicity and autophagy: a mechanistic view

It is strongly believed that aluminum is one of the insalubrious agents because of its neurotoxicity effects and influences on amyloid β (Aβ) production and tau protein hyperphosphorylation following oxidative stress, as one of the initial events in neurotoxicity. The autophagy process plays a considerable role in neurons in preserving intracellular homeostasis and recycling organelles and proteins, especially Aβ and soluble tau. Thus, autophagy is suggested to ameliorate aluminum neurotoxicity effects, and dysfunction of this process can lead to an increase in detrimental proteins. However, the relationship between aluminum neurotoxicity and autophagy dysregulation in some dimensions remains unclear. In the present review, we want to give an overview of the autophagy roles in aluminum neurotoxicity and how dysregulation of autophagy can affect aluminum neurotoxicity.

Zebrafish: A Pharmacological Model for Learning and Memory Research

Learning and memory are essential to organism survival and are conserved across various species, especially vertebrates. Cognitive studies involving learning and memory require using appropriate model organisms to translate relevant findings to humans. Zebrafish are becoming increasingly popular as one of the animal models for neurodegenerative diseases due to their low maintenance cost, prolific nature and amenability to genetic manipulation. More importantly, zebrafish exhibit a repertoire of neurobehaviors comparable to humans. In this review, we discuss the forms of learning and memory abilities in zebrafish and the tests used to evaluate the neurobehaviors in this species. In addition, the pharmacological studies that used zebrafish as models to screen for the effects of neuroprotective and neurotoxic compounds on cognitive performance will be summarized here. Lastly, we discuss the challenges and perspectives in establishing zebrafish as a robust model for cognitive research involving learning and memory. Zebrafish are becoming an indispensable model in learning and memory research for screening neuroprotective agents against cognitive impairment.

3-Aminopyridine Salicylidene: A Sensitive and Selective Chemosensor for the Detection of Cu(II), Al(III), and Fe(III) with Application to Real Samples

Interest in developing selective and sensitive metal sensors for environmental, biological, and industrial applications is mounting. The goal of this work was to develop a sensitive and selective sensor for certain metal ions in solution. The goal was achieved via (i) preparing the sensor ((E)-2-((pyridine-3-ylimino)methyl)phenol) (3APS) using microwave radiation in a short time and high yield and (ii) performing spectrophotometric titrations for 3APS with several metal ions. 3APS, a Schiff base, was prepared in 5 min and in a high yield (95%) using microwave-assisted synthesis. The compound was characterized by FTIR, XRD, NMR, and elemental analysis. Spectrophotometric titration of 3APS was performed with Al(III), Ba(II), Cd(II), Co(II), Cu(II), Fe(III), Mn(II), Ni(II), and Zn(II). 3APS showed good abilities to detect Al(III) and Fe(III) ions fluorescently and Cu(II) ion colorimetrically. The L/M stoichiometric ratio was 2:1 for Cu(II) and 1:1 for Al(III) and Fe(III). Low detection limits (μg/L) of 324, 20, and 45 were achieved for Cu(II), Al(III), and Fe(III), respectively. The detection of aluminum was also demonstrated in antiperspirant deodorants, test strips, and applications in secret writing. 3APS showed high fluorescent selectivity for Al(III) and Fe(III) and colorimetric selectivity towards Cu(II) with detection limits lower than corresponding safe drinking water guidelines.

Global Proteomic Profile of Aluminum-Induced Hippocampal Impairments in Rats: Are Low Doses of Aluminum Really Safe?

Hippocampus is the brain area where aluminum (Al) accumulates in abundance and is widely associated with learning and memory. In the present study, we evaluate behavioral, tissue, and proteomic changes in the hippocampus of Wistar rats caused by exposure to doses that mimic human consumption of aluminum chloride (AlCl₃) in urban areas. For this, male Wistar rats were divided into two groups: Control (distilled water) and AlCl₃ (8.3 mg/kg/day), both groups were exposed orally for 60 days. After the Al exposure protocol, cognitive functions were assessed by the Water maze test, followed by a collection for analysis of the global proteomic profile of the hippocampus by mass spectrometry. Aside from proteomic analysis, we performed a histological analysis of the hippocampus, to the determination of cell body density by cresyl violet staining in Cornu Ammonis fields (CA) 1 and 3, and hilus regions. Our results indicated that exposure to low doses of aluminum chloride triggered a decreased cognitive performance in learning and memory, being associated with the deregulation of proteins expression, mainly those related to the regulation of the cytoskeleton, cellular metabolism, mitochondrial activity, redox regulation, nervous system regulation, and synaptic signaling, reduced cell body density in CA1, CA3, and hilus.

Activation of PI3k/Akt/mTOR Signaling Induces Deposition of p-tau to Promote Aluminum Neurotoxicity

Aluminum neurotoxicity impairs learning and memory ability, but the molecular mechanism has not been elucidated. The aim of this study was to examine the role of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling in regulating the expression of synaptic plasticity-related proteins (PRPs) and p-tau deposition to explore the mechanism underlying aluminum-induced neurotoxicity. We constructed a sub-chronic aluminum-exposed Sprague Dawley (SD) rat model to assess aluminum neurotoxicity in vivo. The learning and memory abilities of rats were examined using the Morris water maze test. We also assessed the effect of aluminum in vitro using rat pheochromocytoma (PC12) cells. To explore the role of PI3K/Akt/mTOR signaling in aluminum neurotoxicity, we used the PI3K inhibitor wortmannin and the mTOR inhibitor rapamycin in aluminum-treated PC12 cells. Protein expression was examined by western blotting. Aluminum disrupted the learning and memory abilities of SD rats. Mechanistically, aluminum reduced the levels of the synaptic PRPs (cAMP-response element binding protein (CREB), glutamate receptor 1 (GluR1), glutamate receptor 2 (GluR2), and postsynaptic density protein 95 (PSD-95), and it increased p-tau deposition in the hippocampus of SD rats. We observed similar results in aluminum-treated PC12 cells. Further, PI3K/Akt/mTOR signaling was abnormally activated in aluminum-treated PC12 cells, and treatment with rapamycin reversed the decrease in synaptic PRPs levels and the increase in p-tau deposition. In conclusion, the activation of PI3K/Akt/mTOR signaling reduces the levels of synaptic PRPs and increases p-tau deposition induced by aluminum. Therefore, the PI3K/Akt/mTOR pathway participates in the mechanism of aluminum neurotoxicity.

Involvement of Mitophagy in Primary Cultured Rat Neurons Treated with Nanoalumina

The aim of this study was to explore the influence of the neurotoxicity of nanoalumina on primarily cultured neurons. Normal control, particle size control, aluminum, micron-alumina, and nanoalumina at 50-nm and 13-nm particle sizes were included as subjects to evaluate the level of apoptosis, necrosis, and autophagy in primarily cultured neurons and further explore the mitophagy induced by nanoalumina. The results demonstrated that nanoalumina could induce neuronal cell apoptosis, necrosis, and autophagy, among which autophagy was the most notable. When the autophagy inhibitor was added to the nanoalumina-treated group, it significantly downregulated the protein expression levels of Beclin-1 and LC3II/LC3. Observation under a transmission electron microscope and a fluorescence microscope revealed mitophagy characteristics induced by nanoalumina. Additionally, the neurotoxicological effects induced by nanoalumina were more significant than those induced by aluminum and in a particle size-dependent manner.

Associations Between Plasma Metals and Cognitive Function in People Aged 60 and Above

The objective of the study was to explore the relationship between the plasma levels of 22 metals and cognition status in older adults aged 60 years and above. A cross-sectional survey was conducted between 2018 and 2019. Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the concentrations of metals, and a mini-mental state examination (MMSE) questionnaire was used to estimate the cognition status of the elderly. Based on the years of education and MMSE scores, the participants were separated into the normal and impaired cognition groups. Lasso regression, logistic regression, and restricted cubic spline models were used to explore the relationship between the metals and cognitive status. A total of 1667 subjects were included in the study, and 333 (19.97%) of the participants had impaired cognition. Then, 12 metals, including Al, Fe, Ni, Cu, As, Se, Rb, Sr, Mo, Cd, Sn, and Sb were selected by lasso regression. Before the multivariate adjustment, Al and Cu were associated with the risk of increasing cognitive impairment (OR = 1.756, 95% CI: 1.166-2.646, P = 0.007; OR = 1.519, 95% CI: 1.050-2.197, P = 0.026, respectively). By contrast, Rb was associated with a decrease in the risk of cognitive impairment (OR = 0.626, 95% CI: 0.427-0.918, P = 0.017), but Cd was significantly associated with an increase in this risk (OR = 1.456, 95% CI: 1.003-2.114, P = 0.048). After multivariate adjustment, only Al (OR = 1.533, 95% CI: 1.000-2.350, P = 0.050) maintained a borderline difference with the risk of cognitive impairment. A significant positive correlation was found between the risk of cognitive impairment and Al, Cu, and Cd, contrary to the negative correlation found with Rb.

Curcumin can improve Parkinson's disease via activating BDNF/PI3k/Akt signaling pathways

Parkinson's disease is a common progressive neurodegenerative disease, and presently has no curative agent. Curcumin, as one of the natural polyphenols, has great potential in neurodegenerative diseases and other different pathological settings. The brain-derived neurotrophic factor (BDNF) and phosphatidylinositol 3 kinase (PI3k)/protein kinase B (Akt) signaling pathways are significantly involved nerve regeneration and anti-apoptotic activities. Currently, relevant studies have confirmed that curcumin has an optimistic impact on neuroprotection via regulating BDNF and PI3k/Akt signaling pathways in neurodegenerative disease. Here, we summarized the relationship between BDNF and PI3k/Akt signaling pathway, the main biological functions and neuroprotective effects of curcumin via activating BDNF and PI3k/Akt signaling pathways in Parkinson's disease. This paper illustrates that curcumin, as a neuroprotective agent, can delay the progression of Parkinson's disease by protecting nerve cells.

Necrostatin-1 Relieves Learning and Memory Deficits in a Zebrafish Model of Alzheimer's Disease Induced by Aluminum

Aluminum (Al) is considered one of the environmental risk factors for Alzheimer's disease (AD). The present study aims to establish a zebrafish AD model induced by Al and explore if necrostation-1 (Nec-1), a specific inhibitor of necroptosis, is effective in relieving learning and memory deficits in the zebrafish AD models. We treated adult zebrafish with aluminum trichloride at various doses for 1 month, followed by a T-maze test to evaluate learning and memory performance. Al concentration, levels of acetylcholine (Ach), and AD-related protein and gene expression in the brain tissue were evaluated in the zebrafish AD models. Our results demonstrated that in the brain tissue of Al-treated zebrafish, Al accumulated, Ach levels decreased, and AD-related genes and proteins increased. As a result, the learning and memory performance of Al-treated zebrafish was impaired. This suggested that a zebrafish AD model was established. To test the effect of Nec-1 on the zebrafish AD model, we added Nec-1 into the culture medium of the Al-treated adult zebrafish. The results demonstrated that Nec-1 could relive the learning and memory deficits, enhance Ach levels and the numbers of neural cells, and impact necroptosis-related gene expression. We concluded that Nec-1 could reverse Al-induced learning and memory impairment and had potential theoretical value in the zebrafish AD model.

Whole-transcriptome analysis of aluminum-exposed rat hippocampus and identification of ceRNA networks to investigate neurotoxicity of Al

Aluminum is a known neurotoxin that can induce Aβ deposition and abnormal phosphorylation of tau protein, leading to Alzheimer disease (AD)-like damages such as neuronal damage and decreased learning and memory functions. In this study, we constructed a rat model of subchronic aluminum maltol exposure, and the whole-transcriptome sequencing was performed on the hippocampus of the control group and the middle-dose group. A total of 167 miRNAs, 37 lncRNAs, 256 mRNAs, and 64 circRNAs expression changed. The Kyoto Encyclopedia of Genes and Genomes showed that PI3K/AKT pathway was the most enriched pathway of DEGs, and IRS1 was the core molecule in the PPI network. circRNA/lncRNA-miRNA-mRNA networks of all DEGs, DEGs in the PI3K/AKT pathway, and IRS1 were constructed by Cytoscape. Molecular experiment results showed that aluminum inhibited the IRS1/PI3K/AKT pathway and increased the content of Aβ and tau. In addition, we also constructed an AAV intervention rat model, proving that inhibition of miR-96-5p expression might resist aluminum-induced injury by upregulating expression of IRS1. In general, these results suggest that the ceRNA networks are involved in the neurotoxic process of aluminum, providing a new strategy for studying the toxicity mechanism of aluminum and finding biological targets for the prevention and treatment of AD.

Longitudinal study of the effects of occupational aluminium exposure on workers' cognition

OBJECTIVE

To explore the effects of occupational aluminium(Al) exposure on workers' cognition through a longitudinal study.

METHODS

The study population consisted of 276 workers in an Al factory. In 2014, we used inductively coupled plasma mass spectrometry (ICP-MS) to determine the plasma aluminium (P-Al) concentration of the workers, and a combined questionnaire to test the workers' cognitive function. Followed-up in 2016, the workers were tested again for cognitive function. Generalized linear regression was used to assess the association between P-Al concentration and cognitive scores, and multivariable logistic regression was used to assess the risk of cognitive decline caused by Al exposure.

RESULTS

Generalized linear regression results showed that a non-significant association was found between the P-Al concentration and cognitive test scores (P > 0.05) in 2014. Two years later, each 10-fold increase in P-Al concentration was inversely associated with the score of Mini-Mental state examination (MMSE) (β: -0.53, 95% CI: -0.86, -0.20) and Fuld object memory evaluation (FOME) (β: -0.93, 95% CI: -1.62, -0.24). Each 10-fold increase in P-Al concentration was inversely associated with MMSE_2016-2014 (β: -0.38, 95% CI: -0.74, -0.01) and FOME_2016-2014 (β: -1.20, 95% CI: -1.95, -0.45). There was a statistically significant difference in the average annual rate of change of MMSE and FOME with the tertile of P-Al concentration increase (P < 0.05). The multivariable logistic regression results showed that as the P-Al concentration increased, the risk of a FOME score decline increased (P_trend = 0.009).

CONCLUSIONS

Continuous occupational Al exposure can damage workers' overall cognitive ability, especially episodic memory function.

Nicotinamide: Oversight of Metabolic Dysfunction Through SIRT1, mTOR, and Clock Genes

Metabolic disorders that include diabetes mellitus present significant challenges for maintaining the welfare of the global population. Metabolic diseases impact all systems of the body and despite current therapies that offer some protection through tight serum glucose control, ultimately such treatments cannot block the progression of disability and death realized with metabolic disorders. As a result, novel therapeutic avenues are critical for further development to address these concerns. An innovative strategy involves the vitamin nicotinamide and the pathways associated with the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and clock genes. Nicotinamide maintains an intimate relationship with these pathways to oversee metabolic disease and improve glucose utilization, limit mitochondrial dysfunction, block oxidative stress, potentially function as antiviral therapy, and foster cellular survival through mechanisms involving autophagy. However, the pathways of nicotinamide, SIRT1, mTOR, AMPK, and clock genes are complex and involve feedback pathways as well as trophic factors such as erythropoietin that require a careful balance to ensure metabolic homeostasis. Future work is warranted to gain additional insight into these vital pathways that can oversee both normal metabolic physiology and metabolic disease.