Neurotoxic characteristics of spatial recognition damage of the hippocampus in mice following subchronic peroral exposure to TiO2 nanoparticles

Exposure to nanoplastics exacerbates light pollution hazards to mammalian

Environmental light pollution adversely affects brain function, disturbing circadian rhythms and negatively impacting human health. Nanoplastics (NPs) pollution is pervasive in the human environment, and their minuscule size facilitates entry into the body, particularly invading brain and compromising its functionality. However, whether NPs infiltrate rhythm-regulated brain regions and disrupt circadian rhythms in organisms remains unclear. Our study demonstrates that exposure to NPs in mice perturbs normal circadian rhythms. Specifically, NPs invade the suprachiasmatic nucleus (SCN), affecting the circadian clock genes network and altering the regular oscillations of core clock genes. Exposure to NPs renders the intrinsic rhythms more susceptible to disruption by light pollution, resulting in more pronounced disorder to metabolism, immune regulation, and brain function. This work is the first to investigate the combined effects of ambient light pollution and NPs pollution on mammalian health, and our findings suggest that NPs amplify the health impacts of light pollution. These findings also highlight that efforts to mitigate human health risks from environmental pollutants should begin to consider the synergistic effects of various classes of pollutants.

Neuroprotective potential of Betulinic acid against TIO2NP induced neurotoxicity in zebrafish

Betulinic acid (BA) is a natural triterpenoid extracted from Bacopa monnieri. BA has been reported to be used as a neuroprotective agent, but their molecular mechanisms are still unknown. Therefore, in this study, we attempted to investigate the precise mechanism of BA for its protective effect against Titanium dioxide nanoparticles (TiO2NP) induced neurotoxicity in zebrafish. Hence, our study observation showed that 10 µg/ml dose of TiO2NP caused a rigorous behavioral deficit in zebrafish. Further, biochemical analysis revealed TiO2NP significantly decreased GSH, and SOD, and increased MDA, AChE, TNF-α, IL-1β, and IL-6 levels, suggesting it triggers oxidative stress and neuroinflammation. However, BA at doses of 2.5,5,10 mg/kg improved behavioral as well as biochemical changes in zebrafish brain. Moreover, BA also significantly raised the levels of DA, NE, 5-HT, and GABA and decreased glutamate levels in TiO2NP-treated zebrafish brain. Our histopathological analysis proved that TiO2NP causes morphological changes in the brain. These changes were expressed by increasing pyknotic neurons, which were dose-dependently reduced by Betulinic acid. Likewise, BA upregulated the levels of NRF-2 and HO-1, which can reduce oxidative stress and neuroinflammation. Thus, our study provides evidence for the molecular mechanism behind the neuroprotective effect of Betulinic acid. Rendering to the findings, we can consider BA as a suitable applicant for the treatment of AD-like symptoms.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Recognition and detection technology for microplastic, its source and health effects

Microplastic (MP) is ubiquitous in the environment which appeared as an immense intimidation to human and animal health. The plastic fragments significantly polluted the ocean, fresh water, food chain, and other food items. Inadequate maintenance, less knowledge of adverse influence along with inappropriate usage in addition throwing away of plastics items revolves present planet in to plastics planet. The present study aims to focus on the recognition and advance detection technologies for MPs and the adverse effects of micro- and nanoplastics on human health. MPs have rigorous adverse effect on human health that leads to condensed growth rates, lessened reproductive capability, ulcer, scrape, and oxidative nervous anxiety, in addition, also disturb circulatory and respiratory mechanism. The detection of MP particles has also placed emphasis on identification technologies such as scanning electron microscopy, Raman spectroscopy, optical detection, Fourier transform infrared spectroscopy, thermo-analytical techniques, flow cytometry, holography, and hyperspectral imaging. It suggests that further research should be explored to understand the source, distribution, and health impacts and evaluate numerous detection methodologies for the MPs along with purification techniques.

Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review

The increasing use of titanium dioxide nanoparticles (TiO2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO2 NPs on both humans and the environment. Notably, TiO2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO2 NPs in different species and in vitro models. Following exposure, TiO2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO2 NPs. However, a systematic comparison of the neurotoxic effects of TiO2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO2 NPs.

Advances in genotoxicity of titanium dioxide nanoparticles in vivo and in vitro

Titanium dioxide nanoparticles (TiO₂ NPs) are currently one of the most widely used nanomaterials. Due to an increasing scope of applications, the exposure of humans to TiO₂ NP is inevitable, such as entering the body through the mouth with food additives or drugs, invading the damaged skin with cosmetics, and entering the body through the respiratory tract during the process of production and handling. Compared with TiO₂ coarse particles, TiO₂ NPs have stronger conductivity, reaction activity, photocatalysis, and permeability, which may lead to greater toxicity to organisms. Given that TiO₂ was classified as a category 2B carcinogen (possibly carcinogenic to humans), the genotoxicity of TiO₂ NPs has become the focus of attention. There have been a series of previous studies investigating the potential genotoxicity of TiO₂ NPs, but the existing research results are still controversial and difficult to conclude. More than half of studies have shown that TiO₂ NPs can cause genotoxicity, suggesting that TiO₂ NPs are likely to be genotoxic to humans. And the genotoxicity of TiO₂ NPs is closely related to the exposure concentration, mode and time, and experimental cells/animals as well as its physicochemical properties (crystal type, size, and shape). This review summarized the latest research progress of related genotoxic effects through in vivo studies and in vitro cell tests, hoping to provide ideas for the evaluation of TiO₂ NPs genotoxicity.

Acute titanium dioxide nanoparticles exposure impaired spatial cognitive performance through neurotoxic and oxidative mechanisms in Wistar rats

CONTEXT

Titanium dioxide nanoparticles (TiO2-NPs) are used in many commercial products. However, their effects on human and animal organism remained to be clarified.

OBJECTIVE

The present study aimed to investigate the effects of TiO2-NPs on the behavioural performance, monoamine neurotransmitters and oxidative stress in the rat brain.

MATERIAL AND METHODS

Rats were injected intravenously with a single dose of TiO2-NPs (20 mg/kg body weight) and were subjected to cognitive and emotional tests using Morris water maze and elevated plus maze.

RESULTS

Cognitive capacity as well as the emotional reactivity were significantly disrupted, in TiO2-NPs-administered rats compared to control group. These behavioural effects were correlated with changes in brain neurotransmitter contents reflected by a significant increase in dopamine and a decrease in serotonin levels. TiO2-NPs also induced oxidative stress in the brain manifested by increased levels of H2O2 and malondialdehyde, associated with antioxidant enzymes activities disturbance, in particular, superoxide dismutase and catalase activities. Moreover, TiO2-NPs administration caused histological damages in the brain tissue with abundant lymphocytic clusters, capillary dilations, vascular congestion and oedema.

CONCLUSIONS

Acute intravenous injection of TiO2-NPs impaired behaviour performances through brain biochemical and structural changes and precautions should be taken to their usage in food additive and medical applications.

Potential neurotoxicity of titanium implants: Prospective, in-vivo and in-vitro study

Titanium dioxide (TiO₂) is a frequently used biomaterial, particularly in orthopedic and dental implants, and it is considered an inert and benign compound. This has resulted in toxicological scrutiny for TiO₂ in the past decade, with numerus studies showing potential pathologic downstream effects. Herein we describe case report of a 77-year-old male with subacute CNS dysfunction, secondary to breakdown of a titanium-based carotid stent and leading to blood levels 1000 times higher (3 ppm) than the reported normal. We prospectively collected tissues adjacent to orthopedic implants and found a positive correlation between titanium concentration and time of implant in the body (r = 0.67, p < 0.02). Rats bearing titanium implants or intravascularly treated with TiO₂ nanoparticles (TiNP) exhibited memory impairments. A human blood-brain barrier (BBB) in-vitro model exposed to TiNP showed paracellular leakiness, which was corroborated in-vivo with the decrease of key BBB transcripts in isolated blood vessels from hippocampi harvested from TiNP-treated mice. Titanium particles rapidly internalized into brain-like endothelial cells via caveolae-mediated endocytosis and macropinocytosis and induced pro-inflammatory reaction with increased expression of pro-inflammatory genes and proteins. Immune reaction was mediated partially by IL-1R and IL-6. In summary, we show that high levels of titanium accumulate in humans adjacent to orthopedic implants, and our in-vivo and in-vitro studies suggest it may be neurotoxic.

Damage to the Blood Brain Barrier Structure and Function from Nano Titanium Dioxide Exposure Involves the Destruction of Key Tight Junction Proteins in the Mouse Brain

Numerous studies have proven that nano titanium dioxide (nano TiO₂) can accumulate in animal brains, where it damages the blood brain barrier (BBB); however, whether this process involves destruction of tight junction proteins in the mouse brain has not been adequately investigated. In this study, mice were exposed to nano TiO₂ for 30 consecutive days, and then we used transmission electron microscopy to observe the BBB ultrastructure and the Evans blue assay to evaluate the permeability of the BBB. Our data suggested that nano TiO₂ damaged the BBB ultrastructure and increased BBB permeability. Furthermore, we used immunofluorescence and Western blotting to examine the expression of key tight junction proteins, including Occludin, ZO-1, and Claudin-5 in the mouse brain. Our data showed that nano TiO₂ reduced Occludin, ZO-1 and Claudin-5 expression. Taken together, nano TiO₂-induced damage to the BBB structure and function may involve the destruction of key tight junction proteins.

Nano-scaled materials may induce severe neurotoxicity upon chronic exposure to brain tissues: A critical appraisal and recent updates on predisposing factors, underlying mechanism, and future prospects

Owing to their tremendous potential, the inference of nano-scaled materials has revolutionized many fields including the medicine and health, particularly for development of various types of targeted drug delivery devices for early prognosis and successful treatment of various diseases, including the brain disorders. Owing to their unique characteristic features, a variety of nanomaterials (particularly, ultra-fine particles (UFPs) have shown tremendous success in achieving the prognostic and therapeutic goals for early prognosis and treatment of various brain maladies such as Alzheimer's disease, Parkinson's disease, brain lymphomas, and other ailments. However, serious attention is needful due to innumerable after-effects of the nanomaterials. Despite their immense contribution in optimizing the prognostic and therapeutic modalities, biological interaction of nanomaterials with various body tissues may produce severe nanotoxicity of different organs including the heart, liver, kidney, lungs, immune system, gastro-intestinal system, skin as well as nervous system. However, in this review, we have primarily focused on nanomaterials-induced neurotoxicity of the brain. Following their translocation into different regions of the brain, nanomaterials may induce neurotoxicity through multiple mechanisms including the oxidative stress, DNA damage, lysosomal dysfunction, inflammatory cascade, apoptosis, genotoxicity, and ultimately necrosis of neuronal cells. Our findings indicated that rigorous toxicological evaluations must be carried out prior to clinical translation of nanomaterials-based formulations to avoid serious neurotoxic complications, which may further lead to develop various neuro-degenerative disorders.

Presence of Titanium and Toxic Effects Observed in Rat Lungs, Kidneys, and Central Nervous System in vivo and in Cultured Astrocytes in vitro on Exposure by Titanium Dioxide Nanorods

BACKGROUND

Non-spherical titanium dioxide (TiO2) nanoparticles have been increasingly applied in various biomedical and technological fields. Their toxicological characterization is, however, less complete than that of roundish nanoparticles.

MATERIALS AND METHODS

Anatase form TiO2 nanorods, ca. 15x65 nm in size, were applied to cultured astrocytes in vitro and to the airways of young adult Wistar rats in vivo in 5, 10, and 8 mg/kg BW dose for altogether 28 days. Presence of nanorods and cellular damage was investigated in the astrocytes and in rat lungs and kidneys. Functional damage of the nervous system was studied by electrophysiological methods.

RESULTS

The treated astrocytes showed loss of viability without detectable apoptosis. In rats, TiO2 nanorods applied to the airways reached the blood and various organs including the lungs, kidneys, and the central nervous system. In lung and kidney samples, nanorods were observed within (partly damaged) phagolysosomes and attached to organelles, and apoptotic cell death was also detected. In cortical and peripheral electrophysiological activity, alterations corresponding to energy shortage (resulting possibly from mitochondrial damage) and astrocytic dysfunction were detected. Local titanium levels and relative weight of the investigated organs, apoptotic cell death in the lungs and kidneys, and changes in the central and peripheral nervous activity were mostly proportional to the applied doses, and viability loss of the cultured astrocytes was also dose-dependent, suggesting causal relationship of treatments and effects.

CONCLUSION

Based on localization of the visualized nanorods, on neuro-functional changes, and on literature data, the toxic mechanism involved mitochondrial damage, oxidative stress, and apoptotic cell death. These indicate potential human toxicity and occupational risk in case of exposure to rod-shaped TiO2 nanoparticles.

Intrathecally Administered Apelin-13 Alleviated Complete Freund's Adjuvant-Induced Inflammatory Pain in Mice

Apelin is the endogenous ligand for APJ, a G-protein-coupled receptor. Apelin gene and protein are widely distributed in the central nervous system and peripheral tissues. The role of apelin in chronic inflammatory pain is still unclear. In the present study, a mouse model of complete Freund’s adjuvant (CFA)-induced inflammatory pain was utilized, and the paw withdrawal latency/threshold in response to thermal stimulation and Von Frey filament stimulation were recorded after intrathecal (i.t.) injection of apelin-13 (0.1, 1, and 10 nmol/mouse). The mRNA and protein expression, concentration of glutamic acid (Glu), and number of c-Fos immunol staining in lumbar spinal cord (L4/5) were determined. The results demonstrated that Apln gene expression in the lumbar spinal cord was down-regulated in the CFA pain model. Apelin-13 (10 nmol/mouse, i.t.) alleviated CFA-induced inflammatory pain, and it exhibited a more potent antinociceptive effect than apelin-36 and (pyr)apelin-13. The antinociception of apelin-13 could be blocked by APJ antagonist apelin-13(F13A). I.T. apelin-13 attenuated the increased levels of Aplnr, Grin2b, Camk2d, and c-Fos genes expression, Glu concentration, and NMDA receptor 2B (GluN2B) protein expression caused by CFA. Apelin-13 significantly reduced the number of Fos-positive cells in laminae III and IV/V of the dorsal horn. This study indicated that i.t. apelin-13 exerted an analgesic effect against inflammatory pain, which was mediated by activation of APJ, and inhibition of Glu/GluN2B function and neural activity of the spinal dorsal horn.

Molecular mechanism of nanoparticulate TiO2 induction of axonal development inhibition in rat primary cultured hippocampal neurons

Numerous studies have demonstrated the in vitro and in vivo neurotoxicity of nanoparticulate titanium dioxide (nano-TiO₂ ), a mass-produced material for a large number of commercial and industrial applications. The mechanism of nano-TiO₂ -induced inhibition of axonal development, however, is still unclear. In our study, primary cultured hippocampal neurons of 24-hour-old fetal Sprague-Dawley rats were exposed to 5, 15, or 30 μg/mL nano-TiO₂ for 6, 12, and 24 hours, and the toxic effects of nano-TiO₂ exposure on the axons development were detected and its molecular mechanism investigated. Nano-TiO₂ accumulated in hippocampal neurons and inhibited the development of axons as nano-TiO₂ concentrations increased. Increasing time in culture resulted in decreasing axon length by 32.5%, 36.6%, and 53.8% at 6 hours, by 49.4%, 53.8%, and 69.5% at 12 hours, and by 44.5%, 58.2%, and 63.6% at 24 hours, for 5, 15, and 30 μg/mL nano-TiO₂ , respectively. Furthermore, nano-TiO₂ downregulated expression of Netrin-1, growth-associated protein-43, and Neuropilin-1, and promoted an increase of semaphorin type 3A and Nogo-A. These studies suggest that nano-TiO₂ inhibited axonal development in rat primary cultured hippocampal neurons and this phenomenon is related to changes in the expression of axon growth-related factors.

The plastic brain: neurotoxicity of micro- and nanoplastics

Given the global abundance and environmental persistence, exposure of humans and (aquatic) animals to micro- and nanoplastics is unavoidable. Current evidence indicates that micro- and nanoplastics can be taken up by aquatic organism as well as by mammals. Upon uptake, micro- and nanoplastics can reach the brain, although there is limited information regarding the number of particles that reaches the brain and the potential neurotoxicity of these small plastic particles.

Earlier studies indicated that metal and metal-oxide nanoparticles, such as gold (Au) and titanium dioxide (TiO₂) nanoparticles, can also reach the brain to exert a range of neurotoxic effects. Given the similarities between these chemically inert metal(oxide) nanoparticles and plastic particles, this review aims to provide an overview of the reported neurotoxic effects of micro- and nanoplastics in different species and in vitro. The combined data, although fragmentary, indicate that exposure to micro- and nanoplastics can induce oxidative stress, potentially resulting in cellular damage and an increased vulnerability to develop neuronal disorders. Additionally, exposure to micro- and nanoplastics can result in inhibition of acetylcholinesterase activity and altered neurotransmitter levels, which both may contribute to the reported behavioral changes.

Currently, a systematic comparison of the neurotoxic effects of different particle types, shapes, sizes at different exposure concentrations and durations is lacking, but urgently needed to further elucidate the neurotoxic hazard and risk of exposure to micro- and nanoplastics.

The mTOR/GCLc/GSH Pathway Mediates the Dose-Dependent Bidirectional Regulation of ROS Induced by TiO2NPs in Neurogenic Cells

Objective. The effect of TiO2NP exposure on the nervous system and the underlying mechanism remain unclear. The antioxidant effect of TiO2NPs at a low dose was newly found in our study, which was different from the effect at high dose. This study is aimed at exploring the mechanism underlying the antioxidant effects of TiO2NPs at low dose and the induction of ROS accumulation by TiO2NPs at high dose in neurogenic cell lines.Methods. We measured the changes in key molecules in the ROS regulation pathway by western blotting, flow cytometry, and commercial assay kits, and these key molecules were further evaluated to verify their interactions and roles using SH-SY5Y, U251, and SK-N-SH cell lines treated with TiO2NPs.Results. Our results showed that the weak antioxidant effect at low dose was caused by mTOR/GCLc-induced GSH overproduction and GSH-Px activity impairment. ROS accumulation at high dose was caused by a mTOR/GCLc-mediated decrease in GSH production, GSH-Px activity impairment, and dramatic ROS production. Furthermore, we found that the ROS species were mainly O2-⋅, and that SOD played a crucial role in reducing O2-⋅levels before the mTOR protein was activated.Conclusion. We revealed the mechanism underlying the bidirectional regulation of ROS induced by TiO2NPs at different doses in neurogenic cell lines. Our study emphasized the potential neurotoxic effects of NPs at low dose, which should arouse concern about their safety.

In deep evaluation of the neurotoxicity of orally administered TiO2 nanoparticles

Titanium dioxide nanoparticles were widely used in food as dietary supplements, in drugs, in toothpaste, ect. Few numbers of studies were interested to the neurotoxicity of TiO₂ NPs through oral pathway. The present study aims firstly to understand the connection between the physicochemical properties of TiO₂ NPs and their associated toxicological oral pathway by evaluation the colloidal stability of TiO₂ NPs over time in different media simulating physiological gastric, intestinal and serum conditions at 37 °C to be close to the oral administraton. Secondly, this study aims to evaluate the neurotoxicity of a subchronic intragastric administration of TiO₂ NPs to rats. Different doses of anatase TiO₂ NPs were administrated to Wistar rats every day for consecutives eight weeks. Titanium (Ti) content in brain, oxidative antioxidant biomarkers, lipid peroxidation, nitric oxide (NO) levels, tumor necrosis factor-alpha (TNF-α) levels, histophatological changes, degenerated and apoptosis neurons were investigated. Results suggested that TiO₂ NPs can reach the brain and cross the brain blood barrier (BBB) to been accumulated in the brain of rats causing cerebral oxidative stress damage, increasing NO levels and histopathological injury. At higher dose, we observed the most cerebral injury by the highest accumulation of Ti and by the remarkable increase of TNF-α besides to the most increase of degenerated and apoptosis neurons in the brain of exposed rats. TiO₂ NPs led to a neurotoxic damage accompanied by the increase of degenerated and apoptotic neurons in cerebral cortex.

The mechanisms underlying the developmental effects of bisphenol F on zebrafish

With the increasing use of bisphenol F (BPF) as BPA alternative, BPF are widely distributed in multiple environment media. Our previous study demonstrated that BPF possess equivalent toxicity towards zebrafish as BPA, while its toxic mechanism remains largely unknown. To investigate the mechanisms mediating the developmental effects of BPF, zebrafish embryos were exposed to 0.0005, 0.5, and 5.0 mg/L BPF. Morphological examination indicated that BPF exposure led to depigmentation, decreased heart rate, inhibited spontaneous movement, hatch inhibition, and spinal deformation. Motor neuron-green fluorescence zebrafish assay indicated that exposure to 0.5 or 5.0 mg/L BPF affected embryonic motor neuron development, which is consistent with the spinal defect and spontaneous movement inhibition. Transcriptomic analysis showed that genes associated with the observed symptoms, including neuron development (ngln2a, socs3a, fosb), cardiac development (klf2a), and spinal deformation (ngs, col8a1a, egr2a), were down-regulated after exposure to either 0.0005 (environmental relevant concentration) or 0.5 mg/L BPF. This partially explained the mechanisms underlying the effects of BPF. In conclusion, BPF had the potential to affect zebrafish development even at environmental level through down-regulating associated genes.

Subchronic and chronic toxicity evaluation of inorganic nanoparticles for delivery applications

Inorganic nanoparticles provide the opportunity to localize bioactive agents to the target sites and protect them from degradation. In many cases, acute toxicities of inorganic nanoparticles used for delivery applications have been investigated. However, little information is available regarding the long-term toxicity of such materials. This review focuses on the importance of subchronic and chronic toxicity assessment of inorganic nanoparticles investigated for delivery applications. We have attempted to provide a comprehensive review of the available literature for chronic toxicity assessment of inorganic nanoparticles. Where possible correlations are made between particle composition, physiochemical properties, duration, frequency and route of administration, as well as the sex of animals, with tissue and blood toxicity, immunotoxicity and genotoxicity. A critical gap analysis is provided and important factors that need to be considered for long-term toxicology of inorganic nanoparticles are discussed.

Retardation of Axonal and Dendritic Outgrowth Is Associated with the MAPK Signaling Pathway in Offspring Mice Following Maternal Exposure to Nanosized Titanium Dioxide

Exposure to nanosized titanium oxide (nano-TiO₂) has been proven to suppress brain growth in mouse offspring; however, whether retardation of axonal or dendritic outgrowth is associated with activation of the mitogen-activated protein kinase (MAPK) pathway remains unclear. In the present study, pregnant mice were exposed to nano-TiO₂ at 1.25, 2.5, and 5 mg/kg body weight, and the molecular mechanism of axonal or dendritic outgrowth retardation was investigated. The results suggested that nano-TiO₂ crossed the blood-fetal barrier and blood-brain barrier and deposited in the brain of offspring, which retarded axonal and dendritic outgrowth, including the absence of axonal outgrowth, and decreased dendritic filament length, dendritic branching number, and dendritic spine density. Importantly, maternal exposure to nano-TiO₂ increased phosphorylated (p)-extracellular signal-regulated kinase1/2 (ERK1/2, +24.35% to +59.4%), p-p38 (+60.82% to 181.85%), and p-c-jun N-terminal kinase (JNK, +28.28% to 97.28%) expression in the hippocampus of the offspring. These findings suggested that retardation of axonal and dendritic outgrowth in mouse offspring caused by maternal exposure to nano-TiO₂ may be related to excessive activation of the ERK1/2/MAPK signaling pathway. Therefore, the potential toxicity of nano-TiO₂ is a concern, especially in pregnant woman or children who are exposed to nano-TiO₂.

Nano-TiO2 Inhibits Development of the Central Nervous System and Its Mechanism in Offspring Mice

Nano titanium dioxide (Nano-TiO₂) has been applied in food packaging systems and food additives, but it may cause potential neurotoxicity for human and animals. In our study, the effects of nano-TiO₂ exposure during pregnancy/lactation on the development of the central nervous system in offspring mice were examined and its molecular mechanism involving Rho family was investigated. Our findings showed that pregnancy/lactation exposure to nano-TiO₂ resulted in thinning of cerebral and cerebellar cortex, decrease in number of neurons per unit area of cerebrum, edema and nuclear condensation, dysplasia of neurites in hippocampal pyramidal cells, thinning in pyramidal cell layer in hippocampus, and decrease in learning and memory of offspring mice. Furthermore, expressions of Rac1 and Cdc42 involved in axon and dendritic development were decreased, whereas RhoA expression and ratio of RhoA/Rac1 were increased in offspring brain. It implies that exposure to nano-TiO₂ during pregnancy/lactation could result in brain retardation and cognitive impairment in offspring mice, which was closely related to alterations in the expression of Rho protein family. Therefore, application of nano-TiO₂ in daily life should be performed with caution.

Titanium dioxide nanoparticles induce mouse hippocampal neuron apoptosis via oxidative stress- and calcium imbalance-mediated endoplasmic reticulum stress

The purpose of this study was to explore the potential neurotoxicity and the underlying mechanism of titanium dioxide nanoparticles (TiO₂-NPs) to mouse hippocampal neuron HT22 cells. We found that TiO₂-NPs had concentration-dependent and time-dependent cytotoxicities to HT22 cells by the MTT assay. Propidium iodide (PI) staining with FACScan flow cytometry proved that TiO₂-NPs dose-dependently increased the apoptosis rate in HT22 cells, and the apoptotic features were observed by Hochest 33258 and AO/EB staining. The levels of calcium (Ca²⁺) and reactive oxygen species (ROS) were significantly increased in TiO₂-NPs-treated cells. Further studies by western blot and real-time QPCR proved that the protein and mRNA levels of GRP78, IRE-1α, ATF6, CHOP and caspase-12 were up-regulated after TiO₂-NPs treatment, which indicates that TiO₂-NPs-induced cytotoxicity is related to endoplasmic reticulum stress (ERS). Apoptosis-related protein cleaved caspase-3 and pro-apoptotic protein Bax expression levels were up-regulated, and the anti-apoptotic protein Bcl-2 expression level was down-regulated in TiO₂-NPs-treated cells. The antioxidant N-acetyl-L-cysteine (NAC) can significantly reduce TiO₂-NPs-induced ERS characterized by the down-regulation of GRP78 and cleaved caspase-12 levels, which indicates that oxidative stress is participated in TiO₂-NPs-induced ERS. Our study suggests that TiO₂-NPs-induced apoptosis in HT22 cells is through oxidative stress- and calcium imbalance-mediated ERS.

MicroRNA-219 decreases hippocampal long-term potentiation inhibition and hippocampal neuronal cell apoptosis in type 2 diabetes mellitus mice by suppressing the NMDAR signaling pathway

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is a complex polygenic disease that causes hyperglycemia and accounts for 90%-95% of all diabetes mellitus cases. Hence, this study aimed to examine the effects of microRNA-219 (miR-219) on inhibition of long-term potentiation (LTP) and apoptosis of hippocampal neuronal cells in T2DM mice through the N-methyl-d-aspartate receptor (NMDAR) signaling pathway regulation.

METHODS

The T2DM mouse models were established, after which LTP in vivo was recorded by means of electrical biology, and the fasting blood glucose of mice was measured. Next, the density of pyramidal neurons in each group was calculated. Additionally, the expression levels of miR-219, the NMDAR signaling pathway [NMDAR1 (NR) 1, NR2A, and NR2B), downstream target proteins [calmodulin-dependent protein kinase-II (CaMK-II) and cAMP response element binding protein (CREB)], and apoptosis-related factors [Bcl2-associated X protein (Bax), c-caspase-9 and c-caspase-3] in the hippocampal tissues were determined. Finally, immunohistochemistry was applied to detect and measure the positive expression of Bax, caspase-9, and caspase-3 proteins.

RESULTS

The results showed that upregulation of miR-219 increases LTP and density of pyramidal neurons in the hippocampal tissues of mice, while it decreases blood glucose of db/db mice. In addition, miR-219 upregulation also leads to decreased mRNA levels of NR1, NR2A, NR2B, CaMK-II, and CREB and protein levels of NR1, NR2A, NR2B, CaMK-II, CREB, p-CREB, Bax, c-caspase-9, and c-caspase-3. Furthermore, upregulation of miR-219 inhibits positive expression of Bax, caspase-9, and caspase-3 proteins, leading to the suppression of hippocampal neuronal cell apoptosis.

CONCLUSION

The findings from this study indicated that the upregulation of miR-219 decreases LTP inhibition and hippocampal neuronal cell apoptosis in T2DM mice by downregulating the NMDAR signaling pathway, therefore suggesting that MiR-219 might be a future therapeutic strategy for T2DM.

Brain Inflammation, Blood Brain Barrier dysfunction and Neuronal Synaptophysin Decrease after Inhalation Exposure to Titanium Dioxide Nano-aerosol in Aging Rats

Notwithstanding potential neurotoxicity of inhaled titanium dioxide nanoparticles (TiO₂ NPs), the toxicokinetics and consequences on blood-brain barrier (BBB) function remain poorly characterized. To improve risk assessment, we need to evaluate the impact on BBB under realistic environmental conditions and take into account vulnerability status such as age. 12-13 week and 19-month-old male rats were exposed by inhalation to 10 mg/m³ of TiO₂ nano-aerosol (6 hrs/day, 5 day/week, for 4 weeks). We showed an age-dependent modulation of BBB integrity parameters suggesting increased BBB permeability in aging rats. This alteration was associated with a significant increase of cytokines/chemokines in the brain, including interleukin-1β, interferon-γ, and fractalkine as well as a decreased expression of synaptophysin, a neuronal activity marker. These observations, in absence of detectable titanium in the brain suggest that CNS-related effects are mediated by systemic-pathway. Moreover, observations in terms of BBB permeability and brain inflammation underline age susceptibility. Even if TiO₂ NPs were not evidenced in the brain, we observed an association between the exposure to TiO₂ NPs and the dysregulation of BBB physiology associated with neuroinflammation and decreased expression of neuronal activity marker, which was further exacerbated in the brain of aged animal's.

Rosmarinus officinalis L. ameliorates titanium dioxide nanoparticles and induced some toxic effects in rats' blood

Titanium dioxide nanoparticles (TiO₂ NPs) have been widely used as a white pigment in food and drugs. The most important route of human exposure to TiO₂ is through food and drug products containing TiO₂ additives. This study investigates the efficacy of an oral traditional use of rosemary extract in ameliorating some toxic effects induced on blood of TiO₂ NP-intoxicated rats. Rats were given rosemary extract via intragastric administration 1 h before the intragastric administration of 100 mg/kg/day TiO₂ NPs (10 nm) for 60 days. TiO₂ NPs significantly increased serum cholesterol, glucose, and triglyceride levels of rats. They also induced significant oxidative stress and inflammatory and caused DNA damage in peripheral blood leukocytes. The rosemary extract appears to have a significant protective effect by lowering glucose level properties, restoring the lipid profile and showing an antioxidative, anti-inflammatory, and antigenotoxic properties against TiO₂ NPs toxicity. In conclusion, this study gives an encouraging scientific basis for consumers of rosemary leaves to keep on with this culinary habit.

The Regulation of GluN2A by Endogenous and Exogenous Regulators in the Central Nervous System

The NMDA receptor is the most widely studied ionotropic glutamate receptor, and it is central to many physiological and pathophysiological processes in the central nervous system. GluN2A is one of the two main types of GluN2 NMDA receptor subunits in the forebrain. The proper activity of GluN2A is important to brain function, as the abnormal regulation of GluN2A may induce some neuropsychiatric disorders. This review will examine the regulation of GluN2A by endogenous and exogenous regulators in the central nervous system.

Progress of in vivo studies on the systemic toxicities induced by titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO2 NPs) are inorganic materials with a diameter of 1-100 nm. In recent years, TiO2 NPs have been used in a wide range of products, including food, toothpaste, cosmetics, medicine, paints and printing materials, due to their unique properties (high stability, anti-corrosion, and efficient photocatalysis). Following exposure via various routes including inhalation, injection, dermal deposition and gastrointestinal tract absorption, NPs can be found in various organs in the body potentially inducing toxic effects. Thus more attention to the safety of TiO2 NPs is necessary. Therefore, the present review aims to provide a comprehensive evaluation of the toxic effects induced by TiO2 NPs in the lung, liver, stomach, intestine, kidney, spleen, brain, hippocampus, heart, blood vessels, ovary and testis of mice and rats in in vivo experiments, and evaluate their potential toxic mechanisms. The findings will provide an important reference for human risk evaluation and management following TiO2 NP exposure.

Cardiac inflammation involving in PKCε or ERK1/2-activated NF-κB signalling pathway in mice following exposure to titanium dioxide nanoparticles

The evaluation of toxicological effects of nanoparticles (NPs) is increasingly important due to their growing occupational use and presence as compounds in consumer products. Recent researches have demonstrated that long-term exposure to air particulate matter can induce cardiovascular events, but whether cardiovascular disease, such as cardiac damage, is induced by NP exposure and its toxic mechanisms is rarely evaluated. In the present study, when mice were continuously exposed to TiO2 NPs at 2.5, 5 or 10mg/kg BW by intragastric administration for 90days, obvious histopathological changes, and great alterations of NF-κB and its inhibitor I-κB, as well as TNF-α, IL-1β, IL-6 and IFN-α expression were induced. The NPs significantly decreased Ca(2+)-ATPase, Ca(2+)/Mg(2+)-ATPase and Na(+)/K(+)-ATPase activities and enhanced NCX-1 content. The NPs also considerably increased CAMK II and α1/β1-AR expression and up-regulated p-PKCε and p-ERK1/2 in a dose-dependent manner in the mouse heart. These data suggest that low-dose and long-term exposure to TiO2 NPs may cause cardiac damage such as cardiac fragmentation or disordered myocardial fibre arrangement, tissue necrosis, myocardial haemorrhage, swelling or cardiomyocyte hypertrophy, and the inflammatory response was potentially mediated by NF-κB activation via the PKCε or ERK1/2 signalling cascades in mice.

TiO2 nanoparticle-induced neurotoxicity may be involved in dysfunction of glutamate metabolism and its receptor expression in mice

Titanium dioxide nanoparticles (TiO2 NPs) have been used in environmental management, food, medicine, and industry. But TiO2 NPs have been demonstrated to cross the blood-brain barrier and store up in the brain organization, leading to glutamate-mediated neurotoxicity. However, the neurotoxicity in the brain is not well understood. In this study, mice were exposed to 1.25, 2.5, or 5 mg/kg body weight TiO2 NPs for 9 months, and the glutamate-glutamine cyclic pathway and expressions of glutamate receptors associated with the hippocampal neurotoxicity were investigated. Our findings showed elevations of glutamate release and phosphate-activated glutaminase activity, and reductions in glutamine and glutamine synthetase in the hippocampus following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly inhibited the expression of N-methyl-d-aspartate receptor subunits (including NR1, NR2A, and NR2B) and metabotropic glutamate receptor 2 in mouse hippocampus. These findings suggest that the imbalance of glutamate metabolism triggered inhibitions of glutamate receptor expression in the TiO2 NP-exposed hippocampus. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 655-662, 2016.

Mechanism of TiO2 nanoparticle-induced neurotoxicity in zebrafish (Danio rerio)

Zebrafish (Danio rerio) has been used historically for evaluating the toxicity of environmental and aqueous toxicants, and there is an emerging literature reporting toxic effects of manufactured nanoparticles (NPs) in zebrafish embryos. Few researches, however, are focused on the neurotoxicity on adult zebrafish after subchronic exposure to TiO2 NPs. This study was designed to evaluate the morphological changes, alterations of neurochemical contents, and expressions of memory behavior-related genes in zebrafish brains caused by exposures to 5, 10, 20, and 40 μg/L TiO2 NPs for 45 consecutive days. Our data indicated that spatial recognition memory and levels of norepinephrine, dopamine, and 5-hydroxytryptamine were significantly decreased and NO levels were markedly elevated, and over proliferation of glial cells, neuron apoptosis, and TiO2 NP aggregation were observed after low dose exposures of TiO2 NPs. Furthermore, the low dose exposures of TiO2 NPs significantly activated expressions of C-fos, C-jun, and BDNF genes, and suppressed expressions of p38, NGF, CREB, NR1, NR2ab, and GluR2 genes. These findings imply that low dose exposures of TiO2 NPs may result in the brain damages in zebrafish, provide a developmental basis for evaluating the neurotoxicity of subchronic exposure, and raise the caution of aquatic application of TiO2 NPs.

Unraveling the neurotoxicity of titanium dioxide nanoparticles: focusing on molecular mechanisms

Titanium dioxide nanoparticles (TiO2 NPs) possess unique characteristics and are widely used in many fields. Numerous in vivo studies, exposing experimental animals to these NPs through systematic administration, have suggested that TiO2 NPs can accumulate in the brain and induce brain dysfunction. Nevertheless, the exact mechanisms underlying the neurotoxicity of TiO2 NPs remain unclear. However, we have concluded from previous studies that these mechanisms mainly consist of oxidative stress (OS), apoptosis, inflammatory response, genotoxicity, and direct impairment of cell components. Meanwhile, other factors such as disturbed distributions of trace elements, disrupted signaling pathways, dysregulated neurotransmitters and synaptic plasticity have also been shown to contribute to neurotoxicity of TiO2 NPs. Recently, studies on autophagy and DNA methylation have shed some light on possible mechanisms of nanotoxicity. Therefore, we offer a new perspective that autophagy and DNA methylation could contribute to neurotoxicity of TiO2 NPs. Undoubtedly, more studies are needed to test this idea in the future. In short, to fully understand the health threats posed by TiO2 NPs and to improve the bio-safety of TiO2 NPs-based products, the neurotoxicity of TiO2 NPs must be investigated comprehensively through studying every possible molecular mechanism.

Decreased spermatogenesis led to alterations of testis-specific gene expression in male mice following nano-TiO2 exposure

Although TiO2 nanoparticles (NPs) exposure has been demonstrated to cross blood-testis barrier and accumulate in the testis resulting in the reduction of sperm numbers, limited data with respect to the molecular mechanism of decreased spermatogenesis caused by TiO2 NP exposure. In this research, testicular damage, sperm number and alterations in testis-specific gene expressions in male mice induced by intragastric administration with TiO2 NPs for six months were investigated. It was found out that TiO2 NPs could migrate to cells, deposit in the testis and epididymis and thus cause damages to relevant organs, which are, to be more specific, the reductions of total sperm concentrations and sperm motility and an enhancement in the number of abnormal sperms in the cauda epididymis. Furthermore, the individual expression regarding to the mRNAs and proteins of testis-specific genes, including Cdc2, Cyclin B1, Dmcl, TERT, Tesmin, TESP-1, XPD and XRCCI, were significantly declined, whereas Gsk3-β and PGAM4 expressions were greatly elevated in mouse testis due to the exposures, which in fact implied that the reduced spermatogenesis may be involved in the alternated testis-specific gene expressions in those exposed male mice.

A review on potential neurotoxicity of titanium dioxide nanoparticles

As the rapid development of nanotechnology in the past three decades, titanium dioxide nanoparticles (TiO2 NPs), for their peculiar physicochemical properties, are widely applied in consumer products, food additives, cosmetics, drug carriers, and so on. However, little is known about their potential exposure and neurotoxic effects. Once NPs are unintentionally exposed to human beings, they could be absorbed, and then accumulated in the brain regions by passing through the blood-brain barrier (BBB) or through the nose-to-brain pathway, potentially leading to dysfunctions of central nerve system (CNS). Besides, NPs may affect the brain development of embryo by crossing the placental barrier. A few in vivo and in vitro researches have demonstrated that the morphology and function of neuronal or glial cells could be impaired by TiO2 NPs which might induce cell necrosis. Cellular components, such as mitochondrial, lysosome, and cytoskeleton, could also be influenced as well. The recognition ability, spatial memory, and learning ability of TiO2 NPs-treated rodents were significantly impaired, which meant that accumulation of TiO2 NPs in the brain could lead to neurodegeneration. However, conclusions obtained from those studies were not consistent with each other as researchers may choose different experimental parameters, including administration ways, dosage, size, and crystal structure of TiO2 NPs. Therefore, in order to fully understand the potential risks of TiO2 NPs to brain health, figure out research areas where further studies are required, and improve its bio-safety for applications in the near future, how TiO2 NPs interact with the brain is investigated in this review by summarizing the current researches on neurotoxicity induced by TiO2 NPs.

TiO2 Nanoparticle Exposure Decreases Spermatogenesis via Biochemical Dysfunctions in the Testis of Male Mice

TiO2 nanoparticles (NPs) have been demonstrated to suppress spermatogenesis in animals, while there is little data related to the biochemical dysfunctions during spermatogenesis due to exposure to TiO2 NPs. In this study, male mice have been exposed to TiO2 NPs via intragastric administration for 60 consecutive days. The findings showed that TiO2 NP exposure resulted in lesions of testis and epididymis, deductions in sperm concentration and sperm motility, and an increase of the number of abnormal sperm in mice. Furthermore, TiO2 NP exposure with 2.5, 5, or 10 mg/kgbw decreased activities of lactate dehydrogenase (-11.59% to -39.84%), sorbitol dehydrogenase (-23.56% to -57.33%), succinate dehydrogenase (-27.04% to -57.85%), glucose-6-phosphate dehydrogenase (-28.3% to -56.42%), Na(+)/K(+)-ATPase (-15.59% to -53.11%), Ca(2+)-ATPase (-12.44% to -55.41%), and Ca(2+)/Mg(2+)-ATPase (-28.25% to -65.72%), and elevated activities of acid phosphatase (+10.48% to +40.0%), alkaline phosphatase (+20.65% to +64.07%), and total nitric oxide synthase (+0.68- to +2.3-fold) in the testes of mice, respectively. In addition, TiO2 NP exposure caused excessive production of reactive oxygen species (+16.15% to +110.62%), and increased malondialdehyde of lipid peroxidation product (+38.96% to +118.07%), carbonyl of protein oxidative product (+20.98% to +108.1%), and 8-hydroxydeoxyguanosine of DNA oxidative product (+0.9- to +1.83-fold) in the testes, respectively. It implied that spermatogenesis suppression caused by TiO2 NP exposure may be associated with alterations of testicular marked enzymes and oxidative stress in the testes.

Toxicity of titanium dioxide nanoparticles in central nervous system

Titanium dioxide nanoparticles (TiO2 NPs) have found many practical applications in industry and daily life. A widespread application of TiO2 NPs rises the question about safety of their use in the context of potential occupational, environmental and intentional exposure of humans and biota. TiO2 NPs easily enter the body through inhalation, cross blood-brain barrier and accumulate in the brain, especially in the cortex and hippocampus. Toxicity of these NPs and the molecular mechanisms of their action have been studied extensively in recent years. Studies showed that TiO2 NPs exposure resulted in microglia activation, reactive oxygen species production, activation of signaling pathways involved in inflammation and cell death, both in vitro and in vivo. Consequently, such action led to neuroinflammation, further brain injury. A spatial recognition memory and locomotor activity impairment has been also observed.

Suppression of neurite outgrowth of primary cultured hippocampal neurons is involved in impairment of glutamate metabolism and NMDA receptor function caused by nanoparticulate TiO2

Numerous studies have indicated that nano-titanium dioxide (TiO2) can induce neurotoxicity in vitro and in vivo, however, it is unclear whether nano-TiO2 affects neurite outgrowth of hippocampal neurons. In order to investigate the mechanism of neurotoxicity, rat primary cultured hippocampal neurons on the fourth day of culture were exposed to 5, 15, and 30 μg/mL nano-TiO2 for 24 h, and nano-TiO2 internalization, dendritic growth, glutamate metabolism, expression of N-methyl-D-aspartate (NMDA) receptor subunits (NR1, NR2A and NR2B), calcium homeostasis, sodium current (INa) and potassium current (IK) were examined. Our findings demonstrated that nano-TiO2 crossed the membrane into the cytoplasm or nucleus, and significantly suppressed dendritic growth of primary cultured hippocampal neurons in a concentration-dependent manner. Furthermore, nano-TiO2 induced a marked release of glutamate to the extracellular region, decreased glutamine synthetase activity and increased phosphate-activated glutaminase activity, elevated intracellular calcium ([Ca(2+)]i), down-regulated protein expression of NR1, NR2A and NR2B, and increased the amplitudes of the INa and IK. In addition, nano-TiO2 increased nitric oxide and nitrice synthase, attenuated the activities of Ca(2+)-ATPase and Na(+)/K(+)-ATPase, and increased the ADP/ATP ratio in the primary neurons. Taken together, these findings indicate that nano-TiO2 inhibits neurite outgrowth of hippocampal neurons by interfering with glutamate metabolism and impairing NMDA receptor function.

PEGylated carbon nanotubes impair retrieval of contextual fear memory and alter oxidative stress parameters in the rat hippocampus

Carbon nanotubes (CNT) are promising materials for biomedical applications, especially in the field of neuroscience; therefore, it is essential to evaluate the neurotoxicity of these nanomaterials. The present work assessed the effects of single-walled CNT functionalized with polyethylene glycol (SWCNT-PEG) on the consolidation and retrieval of contextual fear memory in rats and on oxidative stress parameters in the hippocampus. SWCNT-PEG were dispersed in water at concentrations of 0.5, 1.0, and 2.1 mg/mL and infused into the rat hippocampus. The infusion was completed immediately after training and 30 min before testing of a contextual fear conditioning task, resulting in exposure times of 24 h and 30 min, respectively. The results showed that a short exposure to SWCNT-PEG impaired fear memory retrieval and caused lipid peroxidation in the hippocampus. This response was transient and overcome by the mobilization of antioxidant defenses at 24 h. These effects occurred at low and intermediate but not high concentration of SWCNT-PEG, suggesting that the observed biological response may be related to the concentration-dependent increase in particle size in SWCNT-PEG dispersions.

Elevated titanium levels in Iraqi children with neurodevelopmental disorders echo findings in occupation soldiers

Anthropogenic release of pollutants into the environment is especially harmful to growing fetuses and young children. These populations are at an increased risk of damage because exposure to pollutants during critical periods of development can cause many impairments. Children's exposure to mixtures of metals could be responsible for the rising numbers of neurological disorders surfacing in Iraqi children. Titanium (Ti) and magnesium (Mg) are heavily used in war industries. Exposure to Ti and Mg has been linked to the dust in occupation soldiers' lungs. Hair samples of children in Hawija, Iraq (n = 13) contained significantly higher levels of Ti compared to Iranian children (n = 13) living near the Iraqi border (2080 ± 940 vs 707 ± 421 μg/kg, p < 0.0001). Magnesium was 1.7 times higher in Hawija children compared to Iranian children (115,763 ± 118,155 vs 67,650 ± 46,729 μg/kg). In samples from Hawija, Ti was 1.3 times higher in children with neurodevelopmental disorders (2198 ± 1108 vs 1942 ± 779 μg/kg), and Mg was 1.9 times higher in children without neurodevelopmental disorders (155,618 ± 140,791 vs 81,602 ± 91,940 μg/kg). Lead, arsenic, and cadmium in Hawija children with neurodevelopmental disorders (n = 6) were 2.5, 2.2, and 1.37 times higher compared to non-disabled children (n = 7). To get a clear understanding of the current status of neurodevelopmental disorders in Iraqi children and to determine the magnitude of this suspected global health issue, registries should be set up to compile and aggregate data from hospitals, clinics, and health centers across the country. Functional registries can develop collaborations with researchers toward finding causes of these disorders in Iraqi children and toward preventing them.

Involvement of neurotrophins and related signaling genes in TiO2 nanoparticle – induced inflammation in the hippocampus of mice

Titanium dioxide nanoparticles (TiO₂ NPs) have been widely used in industry and daily life; their potential neurotoxic effects are of great concern.

Air pollution and your brain: what do you need to know right now

Research links air pollution mostly to respiratory and cardiovascular disease. The effects of air pollution on the central nervous system (CNS) are not broadly recognized. Urban outdoor pollution is a global public health problem particularly severe in megacities and in underdeveloped countries, but large and small cities in the United States and the United Kingom are not spared. Fine and ultrafine particulate matter (UFPM) defined by aerodynamic diameter (<2.5-μm fine particles, PM2.5, and <100-nm UFPM) pose a special interest for the brain effects given the capability of very small particles to reach the brain. In adults, ambient pollution is associated to stroke and depression, whereas the emerging picture in children show significant systemic inflammation, immunodysregulation at systemic, intratechal and brain levels, neuroinflammation and brain oxidative stress, along with the main hallmarks of Alzheimer and Parkinson's diseases: hyperphosphorilated tau, amyloid plaques and misfolded α-synuclein. Animal models exposed to particulate matter components show markers of both neuroinflammation and neurodegeneration. Epidemiological, cognitive, behavioral and mechanistic studies into the association between air pollution exposures and the development of CNS damage particularly in children are of pressing importance for public health and quality of life. Primary health providers have to include a complete prenatal and postnatal environmental and occupational history to indoor and outdoor toxic hazards and measures should be taken to prevent or reduce further exposures.

Nano-sized titanium dioxide-induced splenic toxicity: a biological pathway explored using microarray technology

Titanium dioxide nanoparticles (TiO2 NPs) have been widely used in various areas, and its potential toxicity has gained wide attention. However, the molecular mechanisms of multiple genes working together in the TiO2 NP-induced splenic injury are not well understood. In the present study, 2.5, 5, or 10mg/kg body weight TiO2 NPs were administered to the mice by intragastric administration for 90 consecutive days, their immune capacity in the spleen as well as the gene-expressed characteristics in the mouse damaged spleen were investigated using microarray assay. The findings showed that with increased dose, TiO2 NP exposure resulted in the increases of spleen indices, immune dysfunction, and severe macrophage infiltration as well as apoptosis in the spleen. Importantly, microarray data showed significant alterations in the expressions of 1041 genes involved in immune/inflammatory responses, apoptosis, oxidative stress, stress responses, metabolic processes, ion transport, signal transduction, cell proliferation/division, cytoskeleton and translation in the 10 mg/kg TiO2 NP-exposed spleen. Specifically, Cyp2e1, Sod3, Mt1, Mt2, Atf4, Chac1, H2-k1, Cxcl13, Ccl24, Cd14, Lbp, Cd80, Cd86, Cd28, Il7r, Il12a, Cfd, and Fcnb may be potential biomarkers of spleen toxicity following exposure to TiO2 NPs.

Mechanisms of TiO2 nanoparticle-induced neuronal apoptosis in rat primary cultured hippocampal neurons

Exposure to titanium dioxide nanoparticles (TiO2 NPs) has been demonstrated to decrease learning and memory of animals. However, whether the impacts of these NPs on the recognition function are involved in hippocamal neuron damages is poorly understood. In this study, primary cultured hippocampal neurons from one-day-old fetal Sprague-Dawley rats were exposed to 5, 15, or 30 µg/mL TiO2 NPs for 24 h, we investigated cell viability, ultrastructure, and mitochondrial membrane potential (MMP), calcium homeostasis, oxidative stress, antioxidant capacity, apoptotic signaling pathway associated with the primary cultured hippocamal neuron apoptosis. Our findings showed that TiO2 NP treatment resulted in reduction of cell viability, promoted lactate dehydrogenase release, apoptosis, and increased neuron apoptotic rate in a dose-dependent manner. Furthermore, TiO2 NPs led to [Ca(2+)]i elevation, and MMP reduction, up-regulated protein expression of cytochrome c, Bax, caspase-3, glucose-regulated protein 78, C/EBP homologous protein and caspase-12, and down-regulated bcl-2 expression in the primary cultured hippocampal neurons. These findings suggested that hippocampal neuron apoptosis caused by TiO2 NPs may be associated with mitochondria-mediated signal pathway and endoplasmic reticulum-mediated signal pathway.

TiO2 nanoparticles induced hippocampal neuroinflammation in mice

Titanium dioxide nanoparticles (TiO2 NPs) have been used in various medical and industrial areas. However, the impacts of these nanoparticles on neuroinflammation in the brain are poorly understood. In this study, mice were exposed to 2.5, 5, or 10 mg/kg body weight TiO2 NPs for 90 consecutive days, and the TLRs/TNF-α/NF-κB signaling pathway associated with the hippocampal neuroinflammation was investigated. Our findings showed titanium accumulation in the hippocampus, neuroinflammation and impairment of spatial memory in mice following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly activated the expression of Toll-like receptors (TLR2, TLR4), tumor necrosis factor-α, nucleic IκB kinase, NF-κB-inducible kinase, nucleic factor-κB, NF-κB2(p52), RelA(p65), and significantly suppressed the expression of IκB and interleukin-2. These findings suggest that neuroinflammation may be involved in TiO2 NP-induced alterations of cytokine expression in mouse hippocampus. Therefore, more attention should be focused on the application of TiO2 NPs in the food industry and their long-term exposure effects, especially in the human central nervous system.