Protective effect of methylene blue against copper oxide nanoparticle-induced neurobehavioral toxicity

Adverse Outcome Pathway-Based Strategies to Mitigate Ag2Se Quantum Dot-Induced Neurotoxicity

Silver selenide quantum dots (Ag2Se QDs) show great advantages in tumor imaging due to their excellent optical performance and good biocompatibility. However, the ultrasmall particle size of Ag2Se QDs allows them to cross the blood-brain barrier, thus potentially affecting the central nervous system. Therefore, risk assessment and response strategies for Ag2Se QDs are important. The adverse outcome pathway (AOP) framework makes it possible to develop risk management strategies based on toxicity mechanisms. In this study, using the AOP framework, we constructed causal mechanism relationship diagrams at different biological levels of Ag2Se QD neurotoxicity. In this framework, excess mitochondrial reactive oxygen species (mtROS) triggered Nod-like receptor protein 3 (NLRP3) inflammasome activation in microglia was molecular initiation event (MIE). Proinflammatory mediator secretion and microglia activation were key events (KEs) at the cellular level. Neuroinflammation and neuronal damage were KEs at the organ/tissue level. Altered hippocampal physiology was the adverse outcome (AO) at the individual level. Based on the established AOP framework, further studies confirmed that mtROS-activated nuclear-factor-E2-related factor 2 (Nrf2)/PTEN-induced kinase 1 (PINK1)- mitophagy contributed to weaken the MIE. Molecular docking-assisted molecular biology experiments demonstrated that quercetin (Qu) enhanced this process. This article emphasizes the importance of the AOP in the risk management of nanomaterials. Furthermore, this paper guides the use of natural small-molecule drugs as a strategy to mitigate nanomaterial-induced neurotoxicity.

Mitochondrial pathways of copper neurotoxicity: focus on mitochondrial dynamics and mitophagy

Copper (Cu) is essential for brain development and function, yet its overload induces neuronal damage and contributes to neurodegeneration and other neurological disorders. Multiple studies demonstrated that Cu neurotoxicity is associated with mitochondrial dysfunction, routinely assessed by reduction of mitochondrial membrane potential. Nonetheless, the role of alterations of mitochondrial dynamics in brain mitochondrial dysfunction induced by Cu exposure is still debatable. Therefore, the objective of the present narrative review was to discuss the role of mitochondrial dysfunction in Cu-induced neurotoxicity with special emphasis on its influence on brain mitochondrial fusion and fission, as well as mitochondrial clearance by mitophagy. Existing data demonstrate that, in addition to mitochondrial electron transport chain inhibition, membrane damage, and mitochondrial reactive oxygen species (ROS) overproduction, Cu overexposure inhibits mitochondrial fusion by down-regulation of Opa1, Mfn1, and Mfn2 expression, while promoting mitochondrial fission through up-regulation of Drp1. It has been also demonstrated that Cu exposure induces PINK1/Parkin-dependent mitophagy in brain cells, that is considered a compensatory response to Cu-induced mitochondrial dysfunction. However, long-term high-dose Cu exposure impairs mitophagy, resulting in accumulation of dysfunctional mitochondria. Cu-induced inhibition of mitochondrial biogenesis due to down-regulation of PGC-1α further aggravates mitochondrial dysfunction in brain. Studies from non-brain cells corroborate these findings, also offering additional evidence that dysregulation of mitochondrial dynamics and mitophagy may be involved in Cu-induced damage in brain. Finally, Cu exposure induces cuproptosis in brain cells due mitochondrial proteotoxic stress, that may also contribute to neuronal damage and pathogenesis of certain brain diseases. Based on these findings, it is assumed that development of mitoprotective agents, specifically targeting mechanisms of mitochondrial quality control, would be useful for prevention of neurotoxic effects of Cu overload.

Nervous system exposure of different classes of nanoparticles: A review on potential toxicity and mechanistic studies

Nanoparticles (NPs) are generally defined as very small particles in the size range of 1-100 nm. Due to the rapid development of modern society, many new materials have been developed. The widespread use of NPs in medical applications, the food industry and the textile industry has led to an increase in NPs in the environment and the possibility of human contact, which poses a serious threat to human health. The nervous system plays a leading role in maintaining the integrity and unity of the body and maintaining a harmonious balance with the external environment. Therefore, based on two categories of organic and inorganic NPs, this paper systematically summarizes the toxic effects and mechanisms of NPs released into the nervous system. The results showed that exposure to NPs may damage the nervous system, decrease learning and cognitive ability, and affect embryonic development. Finally, a remediation scheme for NPs entering the body via the environment is also introduced. This scheme aims to reduce the neurotoxicity caused by NPs by supplementing NPs with a combination of antioxidant and anti-inflammatory compounds. The results provide a valuable reference for future research in this field.

Examining the Influence of Zinc Oxide Nanoparticles and Bulk Zinc Oxide on Rat Brain Functions: a Comprehensive Neurobehavioral, Antioxidant, Gene Expression, and Histopathological Investigation

The study aimed to assess the impact of zinc oxide nanoparticles (ZnONPs) on rats' neurobehavior compared to bulk zinc oxide (BZnO). Thirty male Sprague-Dawley rats were randomly assigned to five groups. The control group received Tween 80 (10%), while the ZnONP groups were given ZnONPs at 5 and 10 mg/kg body weight dosages, and the bulk zinc oxide (BZnO) groups received BZnO at the same dosages. Behavioral observations, neurobehavioral examinations, and assessments of brain tissue oxidative markers, neurotransmitter levels, and histopathological changes were performed. The results indicated that ZnONP at a dosage of 5 mg/kg improved general behavior, locomotor activity, memory, and recognition and reduced fearfulness in rats. Conversely, the higher dosage of 10 mg/kg and the bulk form had adverse effects on general behavior, locomotor activity, and learning ability, with the bulk form demonstrating the most severe impact-znONP-5 treatment increased antioxidant enzyme levels and decreased inflammatory markers. BZnO-5 exhibited lower oxidative stress markers, although still higher than BZnO-10. Furthermore, ZnONP-5 and BZnO-5 increased neurotransmitter levels compared to higher dosages. ZnONP-5 upregulated the expression of brain-derived neurotrophic factor (BDNF) mRNA, while BZnO-5 showed increased BDNF mRNA expression and decreased expression of genes related to apoptosis and inflammation. In summary, ZnONPs at 5 mg/kg demonstrated positive effects on rat brain function and behavior, while higher dosages and the bulk form had detrimental effects. In conclusion, the studies emphasized the importance of further assessing various doses and forms of zinc oxide on brain health, highlighting the significance of dosage considerations when using nanomaterials.

Effect of sub-acute exposure of metal-organic framework-199 on cognitive function and oxidative stress level of brain tissue in rat

Metal-Organic Framework-199 (MOF-199) is a subgroup of MOFs that is utilized in different medical fields such as drug delivery. In the current study, the effect of sub-acute exposure to MOF-199 on spatial memory, working memory, inflammatory mediators' expression, and oxidative stress level of brain tissue has been investigated. Thirty-two male Wistar rats were randomly divided into four groups as vehicle, MOF-199 at doses 0.3, 3, or 6 mg/kg. After four injections of relevant interventions via tail vein during 14 days, behavioral parameters were investigated using Y-maze and Morris Water Maze (MWM) tests. Oxidative stress was measured by ferric reducing antioxidant power (FRAP) and thiobarbituric acid-reacting substance (TBARS) tests. The expression levels of TNF-α and IL-1β were assessed by quantitative real-time reverse-transcription PCR (qRT-PCR). No significant differences were observed in working memory, spatial learning and memory of MOF-199 receiving rats. Additionally, the level of oxidative stress and inflammatory genes expression were not remarkably changed in the brain tissues of MOF-199 treated rats. Despite the lack of remarkable toxic effects of sub-acute exposure to MOF-199, more studies with a longer duration of administration are necessary to use this substance for drug delivery systems in diseases related to the nervous system.

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.

Nanoparticles and neurodegeneration: Insights on multiple pathways of programmed cell death regulated by nanoparticles

Currently, nanoparticles (NPs) are extensively applied in the diagnosis and treatment of neurodegenerative diseases (NDs). With the rapid development and increasing exposure to the public, the potential neurotoxicity associated with NDs caused by NPs has attracted the researchers' attentions but their biosafety assessments are still far behind relevant application studies. Based on recent research, this review aims to conduct a comprehensive and systematic analysis of neurotoxicity induced by NPs. The 191 studies selected according to inclusion and exclusion criteria were imported into the software, and the co-citations and keywords of the included literatures were analyzed to find the breakthrough point of previous studies. According to the available studies, the routes of NPs entering into the normal and injured brain were various, and then to be distributed and accumulated in living bodies. When analyzing the adverse effects induced by NPs, we focused on multiple programmed cell deaths (PCDs), especially ferroptosis triggered by NPs and their tight connection and crosstalk that have been found playing critical roles in the pathogenesis of NDs and their underlying toxic mechanisms. The activation of multiple PCD pathways by NPs provides a scientific basis for the occurrence and development of NDs. Furthermore, the adoption of new methodologies for evaluating the biosafety of NPs would benefit the next generation risk assessment (NGRA) of NPs and their toxic interventions. This would help ensure their safe application and sustainable development in the field of medical neurobiology.

Boosting the therapy of glutamine-addiction glioblastoma by combining glutamine metabolism therapy with photo-enhanced chemodynamic therapy

The complete treatment of high grade invasive glioblastoma (GBM) remains to be a great challenge, and it is of great importance to develop innovative therapeutic approaches. Herein, we found that GBM derived from U87 MG cells is a glutamine-addiction tumor, and jointly using glutamine-starvation therapy and photo-enhanced chemodynamic therapy (CDT) can significantly boost its therapy. We rationally fabricated tumor cell membrane coated Cu2-xSe nanoparticles (CS NPs) and an inhibitor of glutamine metabolism (Purpurin) for combined therapy, because glutamine rather than glucose plays a crucial role in the proliferation and growth of GBM cells, and serves as a precursor for the synthesis of glutathione (GSH). The resultant CS-P@CM NPs can be specifically delivered to the tumor site to inhibit glutamine metabolism in tumor cells, suppress tumor intracellular GSH, and increase H2O2 content, which benefit the CDT catalyzed by CS NPs. The cascade reaction can be further enhanced by irradiation with the second near-infrared (NIR-II) light at the maximum concentration of H2O2, which can be monitored by photoacoustic imaging. The NIR-II light irradiation can generate a large amount of reactive oxygen species (ROS) within a short time to kill tumor cells and enhance the CDT efficacy. This is the first work on the treatment of orthotopic malignant GBM through combined glutamine metabolism therapy and photo-enhanced CDT, and provides insights into the treatment of other solid tumors by modulating the metabolism of tumor cells.

Recent advances in the removal of dyes from wastewater using low-cost adsorbents

The presence of hazardous dyes in wastewater cause disastrous effects on living organisms and the environment. The conventional technologies for the remediation of dyes from water have several bottlenecks such as high cost and complex operation. This review aims to present a comprehensive outlook of various bio-sorbents that are identified and successfully employed for the removal of dyes from aqueous environments. The effect of physicochemical characteristics of adsorbents such as surface functional groups, pore size distribution and surface areas are critically evaluated. The adsorption potential at different experimental conditions of diverse bio-sorbents has been also explored and the influence of certain key parameters like solution pH, temperature, concentration of dyes, dosage of bio-sorbent and agitation speed is carefully evaluated. The mechanism of dyes adsorption, regeneration potential of the employed bio-sorbents and their comparison with other commercial adsorbents are discussed. The cost comparison of different adsorbents and key technological challenges are highlighted followed by the recommendations for future research.

Ecotoxicological Effects of Bimetallic PdNi/MWCNT and PdCu/MWCNT Nanoparticles onto DNA Damage and Oxidative Stress in Earthworms

Bimetallic nanoparticles are synthesized using two different metal elements and used recently in many fields. However, limited studies related to the ecotoxic effects of nanoparticles available in the literature. The purpose of this study is to synthesize and characterize bimetallic PdCu/MWCNT and PdNi/MWCNT NPs and investigate their ecotoxic effects on earthworms. For this purpose, we injected approximately 20 µL of various concentrations of bimetallic PdCu/MWCNT and PdNi/MWCNT NPs (1, 10, 100, 1000, and 2000 mg/L) into the coelomic space of earthworms. We evaluated survival rate, malformations, reactive oxygen species (ROS) level, 8-OHdG content, and histopathological changes in earthworms at the 48th hour after exposure. PdCu/MWCNT and PdNi/MWCNT NPs were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) pattern, and Raman-scattering spectroscopy. Toxicological examinations showed that PdCu/MWCNT NPs reduced the survival rate of earthworms (2000 mg/L, 84%) and caused various malformations (various lesions, thinning, swelling, and rupture), but nonsignificant effects of survival rate and malformations were observed in earthworms using PdNi/MWCNT NPs. The histopathological examinations of earthworm tissues exposed with PdNi/MWCNT determined that tissues in all treatment groups had a normal histological appearance. However, at a concentration of 2000 mg/L of PdCu/MWCNT NPs, atrophy in the longitudinal muscle layer and less degenerative cells in the epidermis layer were observed in earthworm tissues. It was determined that PdNi/MWCNT and PdCu/MWCNT NPs caused significant increases in ROS levels and 8-OHdG activity in earthworm tissues after 48 h. Finally, our results demonstrated that the toxicity of PdNi/MWCNT NPs was detected to be lower than PdCu/MWCNT NPs. However, both nanoparticles may pose a toxicological risk at high concentrations (1000 and 2000 mg/L). These findings will provide valuable information to studies on the use of PdNi/MWCNT NPs in wastewater treatment systems, industrial and medical fields, which have been determined to have less ecotoxicological risk.

Hepatorenal protective effect of nano-curcumin against nano‑copper oxide-mediated toxicity in rats: Behavioral performance, antioxidant, anti-inflammatory, apoptosis, and histopathology

BACKGROUND

Metal oxide nanoparticles (NPs) induce oxidative stress that can cause cellular toxicity. A natural antioxidant that can be used to protect tissues from oxidative stress is curcumin.

PURPOSE

In the present study, we evaluated the protective effect of curcumin nanoparticles (curcumin-NPs) against copper oxide nanoparticles (CuO-NPs)-mediated hepatorenal effects on behavioral performance, biochemical markers, antioxidants, inflammation, apoptosis, and histopathology in rats.

STUDY DESIGN

Twenty Wistar adult male rats were randomly divided into four groups (n = 5); Group Ι served as a control, group ΙΙ was orally gavaged with curcumin-NPs (100 mg/Kg), group ΙΙI orally received CuO-NPs (100 mg/kg), and group ΙV received both CuO-NPs and curcumin-NPs orally for 14 days.

METHODS

Behavioral performance, biochemical markers, antioxidants, inflammatory mediators, and apoptotic gene expression were evaluated in addition to histopathological and immunohistochemical examination.

RESULTS

The results revealed that rats exposed to CuO-NPs suffered from behavioral alterations and hepatic and renal damages, which indicated by a marked elevation of serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, urea, uric acid, and creatinine and a decline of total protein. Moreover, there was a significant downregulation in the expression of antioxidants genes, whereas inflammatory mediators expression were upregulated. The histopathological and immunohistochemical examination also corroborated these findings. In contrast, rats co-treated with curcumin-NPs exhibited better behavioral performance, biochemical profile, gene expression, histological architecture, and immunohistochemical staining results.

CONCLUSION

These findings strongly indicated that curcumin-NPs exert significant protection against the behavioral and hepatorenal disorders induced by CuO-NPs toxicity by modulating oxidative stress regulators and gene expression.

HINT1 Is Involved in the Chronic Mild Stress Elicited Oxidative Stress and Apoptosis Through the PKC ε/ALDH-2/4HNE Pathway in Prefrontal Cortex of Rats

Major depressive disorder (MDD) is a severe, highly heterogeneous, and life-threatening psychiatric disease which affects up to 21% of the population worldwide. A new hypothesis suggests that the mitochondrial dysfunction causing oxidative stress (OS) and dysregulation of apoptosis in brain might be one of the key pathophysiological factors in MDD. Histidine triad nucleotide binding protein 1 (HINT1), which was first supposed to be protein kinase C (PKC) inhibitor, has been gradually demonstrated to be involved in diverse neuropsychiatric diseases. It still remains elusive that how HINT1 involves in depression. The present study utilized a rat model exposed to chronic mild stress (CMS) to explore the involvement of HINT1 in depression. Face validity, construct validity and predictive validity of CMS model were comprehensive evaluated in this study. Behavioral tests including sucrose preference test, open field test, and elevated plus maze and forced swimming test revealed that stressed rats displayed elevated level of anxiety and depression compared with the controls. CMS rats showed a significant decrease of superoxide dismutase, and a marked increase malondialdehyde levels in prefrontal cortex (PFC). We also found the CMS rats had elevated expression of HINT1, decreased levels of phosphorylated-PKC ε and aldehyde dehydrogenase-two (ALDH-2), and accumulated 4-hydroxynonenal (4HNE) in PFC. Moreover, CMS increased the levels of cleaved caspase-3 and Bax, and decreased the level of Bcl-2 in PFC. The alterations in behavior and molecule were prevented by antidepressant venlafaxine. These results demonstrated that HINT1 was involved in the CMS elicited OS and apoptosis in PFC, probably through the PKC ε/ALDH-2/4HNE pathway. The results suggest that the suppression of HINT1 might have potential as a novel therapeutic strategy for depression.