Effects of Aluminum Oxide Nanoparticles in the Cerebrum, Hippocampus, and Cerebellum of Male Wistar Rats and Potential Ameliorative Role of Melatonin

Aluminium oxide nanoparticles (Al2O3-NPs) exposure impairs cardiovascular physiology and elevates health risk - proteomic and molecular mechanistic insights

The interactions of nanoparticles with biomolecules lead to toxicopathological outcomes through various mechanisms including oxidative stress. In this regard, the interplay of oxidative stress with other molecular mechanisms of cytotoxicity during aluminium oxide nanoparticles (Al2O3-NPs) induced cardiovascular toxicity was not yet precisely explored. Initially, the human serum protein interaction and its corona composition were explored through the gel/label-free proteomics (nLC-HRMS/MS) method. In addition, endothelial cells (EC) and cardiomyoblasts (CM) cultures were employed along with various oxidative stress and cell stress assays. Further, various expression studies (RT-qPCR, western blot, and immunofluorescence), kinase signalling, and siRNA mediated gene knockout assays were performed. Alongside, the in ovo impact on antioxidant enzymes and metabolomic pathways (1H NMR) in the heart validated the role of oxidative stress during cardiotoxicity. The current outcome illustrates the dose-dependent increase of cytotoxicity and caspase (3 and 9) activation. The dose-dependent elevation and its synergy with cardiovascular stress signalling (ET-1 and Ang-II) illustrate the prominent role of oxidative stress during toxicity. In conclusion, the current study connects the role of the redox system and molecular stress pathways during Al2O3-NPs induced cardiotoxicity which extends the knowledge towards the precise health risk assessment during human exposure.

Toxic effects of aluminum nanoparticles: a review

The objective of this state-of-the-art review is to summarize contemporary data on the potential toxic effects of aluminum nanoparticles (AlNPs) and discuss the underlying molecular mechanisms. In vivo studies using laboratory rodents demonstrate that lungs, liver, brain, and the immune system are the primary targets for AlNPs toxicity. Specifically, inhalation exposure to AlNPs induces lung damage by promoting inflammatory infiltration, airway remodeling, septal thickening, and bronchial hyperresponsiveness. AlNPs-induced liver damage is characterized by hepatocyte degeneration and necrosis, liver sinusoid congestion, inflammation, and fibrosis. AlNPs induces neurotoxicity resulting in neurodegeneration, neuroinflammation, altered neurotransmitter metabolism, and subsequent adverse neurobehavioral outcome. In turn, immunotoxicity of AlNPs is characterized by promotion of systemic inflammation along with impaired phagocytosis. In addition to the toxicity exerted by Al2O3NPs itself, the observed toxic effects of AlNPs may be attributed to Al3+ release from the particles with the subsequent induction of oxidative stress, inflammation, mitochondrial dysfunction, genotoxicity, cell cycle dysregulation, and cell death due to apoptosis, necrosis, and ferroptosis. It is also evident that both the size and the form of AlNPs significantly affect its cytotoxicity. However, further studies are required to explore the mechanisms of toxic effects of AlNPs, as well as its potential adverse effects on human health.

Effects of Aluminum Oxide Nanoparticles in the Spinal Cord of Male Wistar Rats and the Potential Ameliorative Role of Melatonin

Aluminum oxide nanoparticles (Al2O3 NPs) are widely utilized in vaccine manufacturing and other medical preparations. Melatonin has numerous effects as an antioxidant and anti-apoptotic. The purpose of this study was to examine the beneficial impact of melatonin on Al2O3 NPs toxicity in the spinal cord. Forty male rats were divided into four groups: Group I, the negative controls (received standard diet and distilled water); Group II, Al2O3 NPs (received 30 mg/kg bw Al2O3 NPs); Group III, melatonin and Al2O3 NPs (received 30 mg/kg bw Al2O3 NPs + 10 mg/kg bw melatonin); Group IV, melatonin (received 10 mg/kg bw melatonin). All treatments were administered daily for 28 days by gastric gavage. After that, all rats were sacrificed, then, the samples from different spinal cords were subjected to histopathological, biochemical, and immunohistochemical analyses. Al2O3 NPs markedly elevated malondialdehyde and 8-hydroxydeoxyguanosine while inhibiting superoxide dismutase and catalase. Al2O3 NPs also induced histological alterations in both gray and white matter manifested by neuronal degeneration, vacuolation, axonal degeneration, ballooning, and fusion of myelin sheaths. Furthermore, immunohistochemical results displayed a strong positive expression of caspase-3. Conversely, melatonin significantly mitigated the effects of Al2O3 NPs by increasing the activities of antioxidant enzymes and inhibiting malondialdehyde and 8-hydroxydeoxyguanosine. Moreover, melatonin alleviated most histological alterations induced by Al2O3 NPs and reduced caspase-3 immunoreactivity. Collectively, melatonin could protect the spinal cord and mitigate Al2O3 NPs-induced neurotoxicity.

Alumina nanoparticles induce learning and memory impairment in a particle size-dependent and time-dependent manner

The study investigates the influence of alumina nanoparticles (Al2O3 NPs) at varying sizes on the learning and memory of adult ICR mice over different exposure durations. The mice were administered saline or Al2O3 nanoparticles of 10μm, 50 nm, and 13 nm via nasal drip. Following administration, the Morris water maze test was conducted, along with assessments of inflammation, oxidative stress, hippocampal histopathology, and cell death-related proteins. Initially, after acute exposure, a trend emerged where learning and memory gradually declined as nanoparticle size decreased, with the most significant impact observed in the 13 nm Al2O3 group. Upon chronic exposure, there was a significant decline in learning and memory within the Al2O3 NPs groups compared to other groups, accompanied by neuronal loss, swelling, light staining, and disorganization. Concurrently, levels of TNF-α and IL-1β within 7 days, MDA after 7 days, and death-related proteins such as Cathepsin-B, c-caspase3, LC3-II, Beclin1, RIP, and Cathepsin-L showed a linear increase, while SOD and GSH-PX activity steadily decreased. Over time, learning capability decreased, correlating with a sharp reduction in TNF-α and SOD activity, a gradual increase in MDA, c-caspase3, and Beclin1 levels in the Al2O3 NPs group, as well as elevated Cathepsin-L, LC3-II, and RIP levels in the 13 nm Al2O3 group. Consequently, Al2O3 NPs significantly impaired learning and memory in a particle size-dependent manner through initial inflammation and oxidative stress after acute exposure, and time-dependent impairment via escalating oxidative stress and neuronal death.

Polyethylene terephthalate nanoplastics-induced neurotoxicity in adult male Swiss albino mice with amelioration of betaine: a histopathological, neurochemical, and molecular investigation

Medicines, food packaging, personal care products, and cosmetics extensively use polyethylene terephthalate nanoplastics (PET-NaPs). However, they also have harmful impacts on several organs. Betaine demonstrates potent antioxidant and anti-inflammatory characteristics. Our goal was to investigate the detrimental impact of PET-NaPs on the mouse brain and evaluate the neuroprotective properties of betaine. We allocated 40 completely mature male Swiss albino mice into four distinct groups: control group, betaine group, PET-NaPs group, and betaine-co-treated group. Following a 30-day duration, euthanasia was performed on the mice, and analyzed tissue samples were obtained from the cerebrum, cerebellum, and hippocampus. PET-NaPs resulted in an elevated level of malondialdehyde and upregulated cyclooxygenase-2 and interleukin-1 beta (IL-1β) expression while significantly reducing the levels of glutathione and downregulating acetylcholinesterase. The PET-NPs also caused significant changes in the histopathology of the brain tissue, and there was a demonstrable rise in the immunostaining of IL-1β and glial fibrillary acidic proteins. Consequently, betaine effectively alleviated the negative consequences of PET-NaPs. Therefore, betaine possesses the capacity to mitigate the neurotoxic consequences induced by PET-NaPs.

Melatonin intervention to prevent nanomaterial exposure-induced damages: A systematic review and meta-analysis of in vitro and in vivo studies

Given its antioxidant, anti-inflammatory, and antiapoptotic properties, melatonin (MEL), a health-caring food to improve sleep disorders, is hypothesized to protect against nanomaterial exposure-induced toxicity. However, the conclusion derived from different studies seemed inconsistent. A meta-analysis of all available preclinical studies was performed to examine the effects of MEL on nanomaterial-induced damages. Eighteen relevant studies were retrieved through searching five electronic databases up to December 2023. The meta-analysis showed that relative to control, MEL treatment significantly increased cell viability (standardized mean difference [SMD = 1.27]) and alleviated liver function (lowered AST [SMD = -3.89] and ALT [SMD = -5.89]), bone formation (enhanced BV/TV [SMD = 4.13] and lessened eroded bone surface [SMD = -5.40]), and brain nerve (inhibition of AChE activity [SMD = -3.60]) damages in animals. The protective mechanisms of MEL against damages caused by nanomaterial exposure were associated with its antiapoptotic (decreased Bax/Bcl-2 ratio [SMD = -4.50] and caspase-3 levels [dose <100 μM: SMD = -3.66]), antioxidant (decreased MDA [in vitro: SMD = -2.84; in vivo: SMD = -4.27]), and anti-inflammatory (downregulated TNF-α [in vitro: SMD = -5.41; in vivo: SMD = -3.21] and IL-6 [in vitro: SMD = -5.90; in vivo: SMD = -2.81]) capabilities. In conclusion, our study suggests that MEL should be supplemented to prevent damages in populations exposed to nanomaterials.

Protective Role of Melatonin Against Abamectin-Induced Biochemical, Immunohistochemical, and Ultrastructural Alterations in the Testicular Tissues of Rats

Abamectin is one of the most widely used pesticides due to its strong insecticidal and anthelmintic activities. Melatonin is a neurohormone with potent antioxidant, anti-apoptotic, and anti-inflammatory effects. This study aimed to investigate the potential ameliorative effects of melatonin against abamectin-induced testicular toxicity in rats. Twenty-four rats were divided into four groups: control group (1 mL/kg/day corn oil), melatonin-treated group (10 mg/kg/day), abamectin-treated group (0.5 mg/kg/day), and melatonin plus abamectin-treated group. Test substances were administered via oral gavage once daily for 28 days. While MDA and 8-OHdG levels increased in the testicular tissue of rats treated with abamectin, SOD, CAT, GPx, and GST enzyme activities decreased significantly. While interleukin-17 levels, TNF-α, and caspase3 expression increased in the testicular tissue, acetylcholinesterase activity decreased. At the same time, serum gonadotropins (luteinizing and follicle-stimulating hormones) and testosterone levels decreased. Light microscope examinations of testicular tissues revealed severe histopathological changes, such as atrophic hyalinized seminiferous tubules, basement membrane irregularity, degeneration, spermatogenic cell loss, and necrosis. Electron microscopy examinations revealed large vacuoles in Sertoli and spermatogenic cells, swelling and vacuolization in mitochondria, lysosomal structures, and increased pyknotic nuclei. In contrast, melatonin supplementation significantly ameliorated abamectin-induced testicular toxicity in rats through antioxidant, antiapoptotic, and anti-inflammatory mechanisms.

Ameliorating and Therapeutic Impact of Curcumin Nanoparticles Against Aluminum Oxide Nanoparticles Induced Kidney Toxicity, DNA Damage, Oxidative Stress, PCNA and TNFα Alteration in Male Rats

Aluminum oxide nanoparticles (Al2O3 NPs) are among the most extensively utilized nanoparticles in nanotechnology and that have negative impacts on the environment. Therefore, the intention of this work is to investigate the protective and therapeutic effects of curcumin in nanoform (Cur NPs) against Al2O3 NPs induced kidney toxicity, oxidative stress, DNA damage, and changes in necrosis factor alpha (TNFα) and proliferating cell nuclear antigen (PCNA) expressions in male rats. Fifty healthy adult male were divided into five groups [G1, control; G2, received 50 mg/kg/day for 4 weeks of Cur NPs orally; G3, received 6 mg/kg BW orally for 4 weeks of Al2O3 NPs; G4, (Cur NPs + Al2O3 NPs) received Cur NPs and Al2O3 NPs at a dose similar to G2 and G3, respectively for 4 weeks; G5, (Al2O3 NPs + Cur NPs) received Al2O3 NPs at a dose similar to G3 for 4 weeks then received Cur NPs at a dose similar to G2 for another 4 weeks]. Current results revealed that Al2O3 NPs induced a significant elevation in serum urea, creatinine, chloride, calcium, kidney malondialdehyde (MDA), DNA damage, injury, TNFα and PCNA expressions and a significant depletion in serum potassium, kidney superoxide dismutase (SOD), glutathione (GSH) as compared to control. On the other hand, treatments of Al2O3 NPs with Cur NPs induced modulation in all altered parameters and improved kidney functions and structure, with best results for the Al2O3 NPs + Cur NPs than Cur NPs + Al2O3 NPs. In conclusion, Cur NPs has the capacity to mitigate the renal toxicity induced by Al2O3 NPs in male albino rats.

Naringenin mitigates nanoparticulate-aluminium induced neuronal degeneration in brain cortex and hippocampus through downregulation of oxidative stress and neuroinflammation

Alumunium usage and toxicity has been a global concern especially an increased use of nanoparticulated aluminum (Al-NPs) products from the environment and the workplace. Al degrades in to nanoparticulate form in the environment due to the routine process of bioremediation in human body. Al-NPs toxicity plays key role in the pathophysiology of neurodegeneration which is characterised by the development of neurofibrillary tangles and neuritic plaques which correlates to the Alzheimer's disease. This study evaluated the Al-NPs induced neurodegeneration and causative behavioral alterations due to oxidative stress, inflammation, DNA damage, β-amyloid aggregation, and histopathological changes in mice. Furthermore, the preventive effect of naringenin (NAR) as a potent neuroprotective flavonoid against Al-NPs induced neurodegeneration was assessed. Al-NPs were synthesized and examined using FTIR, XRD, TEM, and particle size analyzer. Mice were orally administered with Al-NPs (6 mg/kg b.w.) followed by NAR treatment (10 mg/kg b.w. per day) for 66 days. The spatial working memory was determined by novel object recognition, T-maze, Y-maze, and Morris Water Maze tests. We measured nitric oxide, advanced oxidation of protein products, protein carbonylation, lipid peroxidation, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, reduced glutathione, oxidised glutathione, and acetylcholine esterase, as well as cytokines analysis, immunohistochemistry, and DNA damage. Al-NPs significantly reduced the learning memory power, increased oxidative stress, reduced antioxidant enzymatic activity, increased DNA damage, altered the levels of cytokines, and increased β-amyloid aggregation in the cortex and hippocampus regions of the mice brain. These neurobehavioral impairments, neuronal oxidative stress, and histopathological alterations were significantly attenuated by NAR supplementation. In conclusion, Al-NPs may be potent neurotoxic upon exposure and that NAR could serve as a potential preventive measure in the treatment and management of neuronal degeneration.

Neuroprotective Assessment of Betaine against Copper Oxide Nanoparticle-Induced Neurotoxicity in the Brains of Albino Rats: A Histopathological, Neurochemical, and Molecular Investigation

Copper oxide nanoparticles (CuO-NPs) are commonly used metal oxides. Betaine possesses antioxidant and neuroprotective activities. The current study aimed to investigate the neurotoxic effect of CuO-NPs on rats and the capability of betaine to mitigate neurotoxicity. Forty rats; 4 groups: group I a control, group II intraperitoneally CuO-NPs (0.5 mg/kg/day), group III orally betaine (250 mg/kg/day) and CuO-NPs, group IV orally betaine for 28 days. Rats were subjected to neurobehavioral assessments. Brain samples were processed for biochemical, molecular, histopathological, and immunohistochemical analyses. Behavioral performance of betaine demonstrated increasing locomotion and cognitive abilities. Group II exhibited significantly elevated malondialdehyde (MDA), overexpression of interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α). Significant decrease in glutathione (GSH), and downregulation of acetylcholine esterase (AChE), nuclear factor erythroid 2-like protein 2 (Nrf-2), and superoxide dismutase (SOD). Histopathological alterations; neuronal degeneration, pericellular spaces, and neuropillar vacuolation. Immunohistochemically, an intense immunoreactivity is observed against IL-1β and glial fibrillary acidic protein (GFAP). Betaine partially neuroprotected against CuO-NPs associated alterations. A significant decrease at MDA, downregulation of IL-1β, and TNF-α, a significant increase at GSH, and upregulation of AChE, Nrf-2, and SOD. Histopathological alterations partially ameliorated. Immunohistochemical intensity of IL-1β and GFAP reduced. It is concluded that betaine neuroprotected against most of CuO-NP neurotoxic effects through antioxidant and cell redox system stimulating efficacy.

Environmental aluminum oxide inducing neurodegeneration in human neurovascular unit with immunity

Aluminum oxide nanoparticle (AlNP), a ubiquitous neurotoxin highly enriched in air pollution, is often produced as an inevitable byproduct in the manufacturing of industrial products such as cosmetics and metal materials. Meanwhile, ALNP has emerged as a significant public health concern due to its potential association with neurological diseases. However, the studies about the neurotoxic effects of AlNP are limited, partially due to the lack of physiologically relevant human neurovascular unit with innate immunity (hNVUI). Here, we employed our AlNP-treated hNVUI model to investigate the underlying mechanism of AlNP-driven neurodegeneration. First, we validated the penetration of AlNP across a blood-brain barrier (BBB) compartment and found AlNP-derived endothelial cellular senescence through the p16 and p53/p21 pathways. Our study showed that BBB-penetrating AlNP promoted reactive astrocytes, which produced a significant level of reactive oxygen species (ROS). The astrocytic neurotoxic factors caused neuronal damage, including the synaptic impairment, the accumulation of phosphoric-tau proteins, and even neuronal death. Our study suggests that AlNP could be a potential environmental risk factor of neurological disorders mediated by neuroinflammation.