Nervous System Injury in Response to Contact With Environmental, Engineered and Planetary Micro- and Nano-Sized Particles

Substitution of bridge carbons for sulphur in calix[4]arene-bis-α-hydroxymethylphosphonic acid transformed mobile carrier into ionic channel accompanied with evoked muscle contraction and impaired neurotransmission powered by membrane action of resulting thiocalix[4]arene-bis-α-hydroxymethylphosphonic acid

The action of calix[4]arenes C-424, C-425 and C-1193 has been investigated on suspended cholesterol/egg phosphatidylcholine lipid bilayer in a voltage-clamp mode. Comparative analysis with the membrane action by calix[4]arene-bis-α-hydroxymethylphosphonic acid (C-99) has shown that the substitution of bridge carbons for sulphur and addition of another methyl group to two alkyl tales in the lower rim of former dipropoxycalix[4]arene C-99 transformed mobile carrier that C-99 created in lipid bilayer (Shatursky et al., 2014) into a transmembrane pore as exposure of the bilayer membrane to sulphur-containing derivative dibutoxythiocalix[4]arene C-1193 resulted in microscopic transmembrane current patterns indicative of a channel-like mode of facilitated diffusion. Within all calix[4]arenes tested a net steady-state voltage-dependent transmembrane current was readily achieved only after addition of calix[4]-arene C-1193. In comparison with the membrane action of C-99 the current induced by calix[4]-arene C-1193 exhibited a much weakened anion selectivity passing slightly more current at positive potentials applied from the side of bilayer membrane to which the calix[4]-arene was added. Testing C-1193 for the membrane action against smooth muscle cells of rat uterus or swine myometrium and synaptosomes of rat brain nerve terminals revealed an increase in intracellular concentration of Ca2+ with reduction of the effective hydrodynamic diameter of the smooth muscle cells and enhanced basal extracellular level of neurotransmitters (glutamate and γ-aminobutyric acid) after C-1193-induced depolarization of the nerve terminals.

Multipollutant reciprocal neurological hazard from smoke particulate matter and heavy metals cadmium and lead in brain nerve terminals

Heavy metals, Cd2+ and Pb2+, and carbonaceous air pollution particulate matter are hazardous neurotoxicants. Here, a capability of water-suspended smoke particulate matter preparations obtained from poplar wood (WPs) and polypropylene fibers (medical facemasks) (MPs) to influence Cd2+/Pb2+-induced neurotoxicity, and vice versa, was monitored using biological system, i.e. isolated presynaptic rat cortex nerve terminals. Combined application of Pb2+ and WPs/MPs to nerve terminals in an acute manner revealed that smoke preparations did not change a Pb2+-induced increase in the extracellular levels of excitatory neurotransmitter L-[14C]glutamate and inhibitory one [3H]GABA, thereby demonstrating additive result and no interference of neurotoxic effects of Pb2+ and particulate matter. Whereas, both smoke preparations decreased a Cd2+-induced increase in the extracellular level of L-[14C]glutamate and [3H]GABA in nerve terminals. In fluorimetric measurements, the metals and smoke preparations demonstrated additive effects on the membrane potential of nerve terminals causing membrane depolarisation. WPs/MPs-induced reduction of spontaneous ROS generation was mitigated by Cd2+ and Pb2+. Therefore, a potential variety of multipollutant heavy metal-/airborne particulate-induced effects on key presynaptic processes was revealed. Multipollutant reciprocal neurological hazard through disturbance of the excitation-inhibition balance, membrane potential and ROS generation was evidenced. This multipollutant approach and data contribute to up-to-date environmental quality/health risk estimation.

Mercury-induced excitotoxicity in presynaptic brain nerve terminals: modulatory effects of carbonaceous airborne particulate simulants

Multipollutant approach is a breakthrough in up-to-date environmental quality and health risk estimation. Both mercury and carbonaceous air particulate are hazardous neurotoxicants. Here, the ability of carbonaceous air particulate simulants, i.e. carbon dots obtained by heating of organics, and nanodiamonds, to influence Hg2+-induced neurotoxicity was monitored using biological system, i.e. presynaptic rat cortex nerve terminals. Using HgCl2 and classical reducing/chelating agents, an adequate synaptic parameter, i.e. the extracellular level of key excitatory neurotransmitter L-[14C]glutamate, was selected for further analysis. HgCl2 starting from 5 µM caused an acute and concentration-dependent increase in the extracellular L-[14C]glutamate level in nerve terminals. Combined application of Hg2+ and carbon dots from heating of citric acid/urea showed that this simulant was able to mitigate in an acute manner excitotoxic Hg2+-induced increase in the extracellular L-[14C]glutamate level in nerve terminals by 37%. These carbon dots and Hg2+ acted as a complex in nerve terminals that was confirmed with fluorimetric data on Hg2+-induced changes in their spectroscopic features. Nanodiamonds and carbon dots from β-alanine were not able to mitigate a Hg2+-induced increase in the extracellular L-[14C]glutamate level in nerve terminals. Developed approach can be applicable for monitoring capability of different particles/compounds to have Hg2+-chelating signs in the biological systems. Therefore, among testing simulants, the only carbon dots from citric acid/urea were able to mitigate acute Hg2+-induced neurotoxicity in nerve terminals, thereby showing a variety of effects of carbonaceous airborne particulate in situ and its potential to interfere and modulate Hg2+-associated health hazard.

Disposable facemask waste combustion emits neuroactive smoke particulate matter

Tremendous deposits of disposable medical facemask waste after the COVID-19 pandemic require improvement of waste management practice according to WHO report 2022, moreover facemasks are still in use around the world to protect against numerous airborne infections. Here, water-suspended smoke preparations from the combustion of disposable medical facemasks (polypropylene fibers) were collected; size, zeta potential, surface groups of smoke particulate matter were determined by dynamic light scattering, FTIR and Raman spectroscopy, and their optical properties were characterized. Neurochemical study using nerve terminals isolated from rat cortex revealed a significant decrease in the initial rate of the uptake/accumulation of excitatory and inhibitory neurotransmitters, L-[14C]glutamate and [3H]GABA, and exocytotic release, and also an increase in the extracellular level of these neurotransmitters. Fluorescent measurements revealed that ROS generation induced by hydrogen peroxide and glutamate receptor agonist kainate decreased in nerve terminals. A decrease in the membrane potential of nerve terminals and isolated neurons, the mitochondrial potential and synaptic vesicle acidification was also shown. Therefore, accidental or intentional utilization of disposable medical facemask waste by combustion results in the release of neuroactive ultrafine particulate matter to the environment, thereby contributing to plastic-associated pollution of air and water resources and neuropathology development and expansion.

A comparative multi-level toxicity assessment of carbon-based Gd-free dots and Gd-doped nanohybrids from coffee waste: hematology, biochemistry, histopathology and neurobiology study

Here, a comparative toxicity assessment of precursor carbon dots from coffee waste (cofCDs) obtained using green chemistry principles and Gd-doped nanohybrids (cofNHs) was performed using hematological, biochemical, histopathological assays in vivo (CD1 mice, intraperitoneal administration, 14 days), and neurochemical approach in vitro (rat cortex nerve terminals, synaptosomes). Serum biochemistry data revealed similar changes in cofCDs and cofNHs-treated groups, i.e. no changes in liver enzymes' activities and creatinine, but decreased urea and total protein values. Hematology data demonstrated increased lymphocytes and concomitantly decreased granulocytes in both groups, which could evidence inflammatory processes in the organism and was confirmed by liver histopathology; decreased red blood cell-associated parameters and platelet count, and increased mean platelet volume, which might indicate concerns with platelet maturation and was confirmed by spleen histopathology. So, relative safety of both cofCDs and cofNHs for kidney, liver and spleen was shown, whereas there were concerns about platelet maturation and erythropoiesis. In acute neurotoxicity study, cofCDs and cofNHs (0.01 mg/ml) did not affect the extracellular level of L-[14C]glutamate and [3H]GABA in nerve terminal preparations. Therefore, cofNHs demonstrated minimal changes in serum biochemistry and hematology assays, had no acute neurotoxicity signs, and can be considered as perspective biocompatible non-toxic theragnostic agent.

Particulate matter and ultrafine particles in urban air pollution and their effect on the nervous system

According to the World Health Organization, both indoor and urban air pollution are responsible for the deaths of around 3.5 million people annually. During the last few decades, the interest in understanding the composition and health consequences of the complex mixture of polluted air has steadily increased. Today, after decades of detailed research, it is well-recognized that polluted air is a complex mixture containing not only gases (CO, NO_x, and SO₂) and volatile organic compounds but also suspended particles such as particulate matter (PM). PM comprises particles with sizes in the range of 30 to 2.5 μm (PM₃₀, PM₁₀, and PM_2.5) and ultrafine particles (UFPs) (less than 0.1 μm, including nanoparticles). All these constituents have different chemical compositions, origins and health consequences. It has been observed that the concentration of PM and UFPs is high in urban areas with moderate traffic and increases in heavy traffic areas. There is evidence that inhaling PM derived from fossil fuel combustion is associated with a wide variety of harmful effects on human health, which are not solely associated with the respiratory system. There is accumulating evidence that the brains of urban inhabitants contain high concentrations of nanoparticles derived from combustion and there is both epidemiological and experimental evidence that this is correlated with the appearance of neurodegenerative human diseases. Neurological disorders, such as Alzheimer's and Parkinson's disease, multiple sclerosis, and cerebrovascular accidents, are among the main debilitating disorders of our time and their epidemiology can be classified as a public health emergency. Therefore, it is crucial to understand the pathophysiology and molecular mechanisms related to PM exposure, specifically to UFPs, present as pollutants in air, as well as their correlation with the development of neurodegenerative diseases. Furthermore, PM can enhance the transmission of airborne diseases and trigger inflammatory and immune responses, increasing the risk of health complications and mortality. Therefore, understanding the different levels of this issue is important to create and promote preventive actions by both the government and civilians to construct a strategic plan to treat and cope with the current and future epidemic of these types of disorders on a global scale.

A review of probiotics in the treatment of autism spectrum disorders: Perspectives from the gut–brain axis

Autism spectrum disorders (ASD) are a class of neurodevelopmental conditions with a large societal impact. Despite existing evidence suggesting a link between ASD pathogenesis and gut–brain axis dysregulation, there is no systematic review of the treatment of probiotics on ASD and its associated gastrointestinal abnormalities based on the gut–brain axis. Therefore, we performed an analysis for ASD based on preclinical and clinical research to give a comprehensive synthesis of published evidence of a potential mechanism for ASD. On the one hand, this review aims to elucidate the link between gastrointestinal abnormalities and ASD. Accordingly, we discuss gut microbiota dysbiosis regarding gut–brain axis dysfunction. On the other hand, this review suggests that probiotic administration to regulate the gut–brain axis might improve gastrointestinal symptoms, restore ASD-related behavioral symptoms, restore gut microbiota composition, reduce inflammation, and restore intestinal barrier function in human and animal models. This review suggests that targeting the microbiota through agents such as probiotics may represent an approach for treating subsets of individuals with ASD.

Analysis of Experimental Data on Changes in Various Structures and Functions of the Rat Brain following Intranasal Administration of Fe2O3 Nanoparticles

Particulate matter, including iron nanoparticles, is one of the constituents of ambient air pollution. We assessed the effect of iron oxide (Fe₂O₃) nanoparticles on the structure and function of the brain of rats. Electron microscopy showed Fe₂O₃ nanoparticles in the tissues of olfactory bulbs but not in the basal ganglia of the brain after their subchronic intranasal administration. We observed an increase in the number of axons with damaged myelin sheaths and in the proportion of pathologically altered mitochondria in the brains of the exposed animals against the background of almost stable blood parameters. We conclude that the central nervous system can be a target for toxicity of low-dose exposure to Fe₂O₃ nanoparticles.

Unscrambling the Role of Redox-Active Biometals in Dopaminergic Neuronal Death and Promising Metal Chelation-Based Therapy for Parkinson's Disease

Biometals are all metal ions that are essential for all living organisms. About 40% of all enzymes with known structures require biometals to function correctly. The main target of damage by biometals is the central nervous system (CNS). Biometal dysregulation (metal deficiency or overload) is related to pathological processes. Chronic occupational and environmental exposure to biometals, including iron and copper, is related to an increased risk of developing Parkinson's disease (PD). Indeed, biometals have been shown to induce a dopaminergic neuronal loss in the substantia nigra. Although the etiology of PD is still unknown, oxidative stress dysregulation, mitochondrial dysfunction, and inhibition of both the ubiquitin-proteasome system (UPS) and autophagy are related to dopaminergic neuronal death. Herein, we addressed the involvement of redox-active biometals, iron, and copper, as oxidative stress and neuronal death inducers, as well as the current metal chelation-based therapy in PD.

Gastrointestinal health: changes of intestinal mucosa and microbiota in patients with ulcerative colitis and irritable bowel syndrome from PM2.5-polluted regions of Ukraine

Here, clinical studies of patients were conducted to assess changes in patients with ulcerative colitis (UC) and irritable bowel syndrome (IBS) associated with air pollution by PM. A comparative study of 100 patients with UC and 75 with IBS from highly (HPRs) and low (LPRs) PM_2.5-polluted regions of Ukraine was conducted. Biopsy of the intestinal mucosa of patients with UC from HPRs showed severe cellular infiltration. Patients with IBS from HPRs had changes in the superficial epithelium (focal desquamation), and inflammatory-cellular infiltration of mucous membrane of the colon. In patients with UC, changes in mucus production were found, which were more significant in HPR patients. PAS response did not depend on the residence; the level of MUC2 was significantly lower in HPR patients with UC (1.12 vs 2.15 au). In patients with UC from HPRs, a decrease in Bacteroidetes (34.0 vs. 39.0 small intestinal bacterial overgrowth (SIBO), ppm) and an increase in Proteobacteria compared to LPRs were shown. In IBS patients, significant differences were found in the level of Proteobacteria, which was higher in HPRs. The level of regulatory flora Akkermansia muciniphila and Faecalibacterium prausnitzii reduced in patients with UC from HPRs. In patients from LPRs, the level of Akkermansia muciniphila raised above normal (2.8 vs 4.7 SIBO, ppm). Similar changes of regulatory flora have been identified in patients with IBS from different regions. Therefore, a more severe course of the disease (more pronounced cellular infiltration and violation of the microbiota) was shown in patients with UC from HPRs as compared to LPRs.

Bio-distribution of Carbon Nanoparticles Studied by Photoacoustic Measurements

Carbon-based nanomaterials are promising for a wide range of biomedical applications, i.e. drug delivery, therapy, and imaging including photoacoustic tomography, where they can serve as contrast agents, biocompatibility and biodistribution of which should be assessed before clinical setting. In this paper, localization of carbon flurooxide nanoparticles, carbon nanodots from β-alanine, carbon nanodots from urea and citric acid and glucose-ethylenediamine nanoparticles (NPs) in organs of Wistar rats were studied by photoacoustic measurements after 24 h of their intravenous injection. 16 ns light pulse from a Q-switched Nd:YAG laser with 1064 nm wavelength was used as an excitation source. The laser-induced photoacoustic signals were recorded with a ring piezoelectric detector. Light absorption by carbon NPs resulted in noticeable enhancement of the photoacoustic amplitude in the tissues where the NPs were accumulated. The NPs were preferably accumulated in liver, kidneys and spleen, and to a lesser extent in heart and gastrocnemius muscles. Together with remarkable fluorescent properties of the studied carbon nanomaterials, their photoacoustic responses allow their application for bi-modal fluorescence-photoacoustic bio-imaging.

Perinatal hypoxia and thalamus brain region: increased efficiency of antiepileptic drug levetiracetam to inhibit GABA release from nerve terminals

Levetiracetam (LV), 2S-(2-oxo-1-pyrrolidiny1) butanamide, is an antiepileptic drug. The exact mechanisms of anticonvulsant effects of LV remain unclear. In this study, rats (Wistar strain) underwent hypoxia and seizures at the age of 10–12 postnatal days (pd). [3H]GABA release was analysed in isolated from thalamus nerve terminals (synaptosomes) during development at the age of pd 17–19 and pd 24–26 (infantile stage), pd 38–40 (puberty) and pd 66–73 (young adults) in control and after perinatal hypoxia. The extracellular level of [3H]GABA in the preparation of thalamic synaptosomes increased during development at the age of pd 38–40 and pd 66–73 as compared to earlier ones. LV did not influence the extracellular level of [3H]GABA in control and after perinatal hypoxia at all studied ages. Exocytotic [3H]GABA release in control increased at the age of pd 24–26 as compared to pd 17–19. After hypoxia, exocytotic [3H]GABA release from synaptosomes also increased during development. LV elevated [3H]GABA release from thalamic synaptosomes at the age of pd 66–73 after hypoxia and during blockage of GABA uptake by NO-711 only. LV realizes its antiepileptic effects at the presynaptic site through an increase in exocytotic release of [3H]GABA in thalamic synaptosomes after perinatal hypoxia at pd 66–73. LV exhibited a more significant effect in thalamic synaptosomes after perinatal hypoxia than in control ones. The action of LV is age-dependent, and the drug was inert at the infantile stage that can be useful for an LV application strategy in child epilepsy therapy. Keywords: brain development, exocytosis, GABA, levetiracetam, perinatal hypoxia, thalamic synaptosomes

Amphiphilic anti-SARS-CoV-2 drug remdesivir incorporates into the lipid bilayer and nerve terminal membranes influencing excitatory and inhibitory neurotransmission

Remdesivir is a novel antiviral drug, which is active against the SARS-CoV-2 virus. Remdesivir is known to accumulate in the brain but it is not clear whether it influences the neurotransmission. Here we report diverse and pronounced effects of remdesivir on transportation and release of excitatory and inhibitory neurotransmitters in rat cortex nerve terminals (synaptosomes) in vitro. Direct incorporation of remdesivir molecules into the cellular membranes was shown by FTIR spectroscopy, planar phospholipid bilayer membranes and computational techniques. Remdesivir decreases depolarization-induced exocytotic release of L-[¹⁴C] glutamate and [³H] GABA, and also [³H] GABA uptake and extracellular level in synaptosomes in a dose-dependent manner. Fluorimetric studies confirmed remdesivir-induced impairment of exocytosis in nerve terminals and revealed a decrease in synaptic vesicle acidification. Our data suggest that remdesivir dosing during antiviral therapy should be precisely controlled to prevent possible neuromodulatory action at the presynaptic level. Further studies of neurotropic and membranotropic effects of remdesivir are necessary.

Toxicologic Concerns with Current Medical Nanoparticles

Nanotechnology is one of the scientific advances in technology. Nanoparticles (NPs) are small materials ranging from 1 to 100 nm. When the shape of the supplied nanoparticles changes, the physiological response of the cells can be very different. Several characteristics of NPs such as the composition, surface chemistry, surface charge, and shape are also important parameters affecting the toxicity of nanomaterials. This review covered specific topics that address the effects of NPs on nanomedicine. Furthermore, mechanisms of different types of nanomaterial-induced cytotoxicities were described. The distributions of different NPs in organs and their adverse effects were also emphasized. This review provides insight into the scientific community interested in nano(bio)technology, nanomedicine, and nanotoxicology. The content may also be of interest to a broad range of scientists.

Neuromodulation by selective angiotensin-converting enzyme 2 inhibitors

Here, neuromodulatory effects of selective angiotensin-converting enzyme 2 (ACE2) inhibitors were investigated. Two different types of small molecule ligands for ACE2 inhibition were selected using chemical genetic approach, they were synthesized using developed chemical method and tested using presynaptic rat brain nerve terminals (synaptosomes). EBC-36032 (1 µM) increased in a dose-dependent manner spontaneous and stimulated ROS generation in nerve terminals that was of non-mitochondrial origin. Another inhibitor EBC-36033 (MLN-4760) was inert regarding modulation of ROS generation. EBC-36032 and EBC-36033 (100 µM) did not modulate the exocytotic release of L-[¹⁴C]glutamate, whereas both inhibitors decreased the initial rate of uptake, but not accumulation (10 min) of L-[¹⁴C]glutamate by nerve terminals. EBC-36032 (100 µM) decreased the exocytotic release as well as the initial rate and accumulation of [³H]GABA by nerve terminals. EBC-36032 and EBC-36033 did not change the extracellular levels and transporter-mediated release of [³H]GABA and L-[¹⁴C]glutamate, and tonic leakage of [³H]GABA from nerve terminals. Therefore, synthesized selective ACE2 inhibitors decreased uptake of glutamate and GABA as well as exocytosis of GABA at the presynaptic level. The initial rate of glutamate uptake was the only parameter that was mitigated by both ACE2 inhibitors despite stereochemistry issues. In terms of ACE2-targeted antiviral/anti-SARS-CoV-2 and other therapies, novel ACE2 inhibitors should be checked on the subject of possible renin-angiotensin system (RAS)-independent neurological side effects.

A comparative study of wood sawdust and plastic smoke particulate matter with a focus on spectroscopic, fluorescent, oxidative, and neuroactive properties

Here, water-suspended smoke aerosol preparation was synthesized from biomass-based fuel, i.e., a widespread product for residential heating, wood sawdust (WP) (pine, poplar, and birch mixture), and its properties were compared in parallel experiments with the smoke preparation from plastics (PP). Molecular groups in the PM preparations were analyzed using Raman and Fourier-transform infrared spectroscopy. WP was assessed in neurotoxicity studies using rat cortex nerve terminals (synaptosomes). Generation of spontaneous and H2O2-evoked reactive oxygen species (ROS) detected using fluorescent dye 2',7'-dichlorofluorescein in nerve terminals was decreased by WP. In comparison with PP, WP demonstrated more pronounced reduction of spontaneous and H2O2-evoked ROS production. WP completely inhibited glutamate receptor agonist kainate-induced ROS production, thereby affecting the glutamate receptor-mediated signaling pathways. WP decreased the synaptosomal membrane potential in fluorimetric experiments and the synaptosomal transporter-mediated uptake of excitatory and inhibitory neurotransmitters, L-[14C]glutamate and [3H] γ-aminobutyric acid (GABA), respectively. PP decreased the ambient synaptosomal level of [3H]GABA, whereas it did not change that of L-[14C]glutamate. Principal difference between WP and PP was found in their ability to influence the ambient synaptosomal level of [3H]GABA (an increase and decrease, respectively), thereby showing riskiness in mitigation of synaptic inhibition by PP and triggering development of neuropathology.

The ability of carbon nanoparticles to increase transmembrane current of cations coincides with impaired synaptic neurotransmission

Here, carbon nanodots synthesized from β-alanine (Ala-CDs) and detonation nanodiamonds (NDs) were assessed using (1) radiolabeled excitatory neurotransmitters L-[¹⁴C]glutamate, D-[2,3³H]aspartate, and inhibitory ones [³H]GABA, [³H]glycine for registration of their extracellular concentrations in rat cortex nerve terminals; (2) the fluorescent ratiometric probe NR12S and pH-sensitive probe acridine orange for registration of the membrane lipid order and synaptic vesicle acidification, respectively; (3) suspended bilayer lipid membrane (BLM) to monitor changes in transmembrane current. In nerve terminals, Ala-CDs and NDs increased the extracellular concentrations of neurotransmitters and decreased acidification of synaptic vesicles, whereas have not changed sufficiently the lipid order of membrane. Both nanoparticles, Ala-CDs and NDs, were capable of increasing the conductance of the BLM by inducing stable potential-dependent cation-selective pores. Introduction of divalent cations, Zn²⁺ or Cd²⁺ on the particles` application side (cis-side) increased the rate of Ala-CDs pore-formation in the BLM. The application of positive potential (+100 mV) to the cis-chamber with Ala-CDs or NDs also activated the insertion as compared with the negative potential (-100 mV). The Ala-CD pores exhibited a wide-range distribution of conductances between 10 and 60 pS and consecutive increase in conductance of each major peak by ~10 pS, which suggest the clustering of the same basic ion-conductive structure. NDs also formed ion-conductive pores ranging from 6 pS to 60 pS with the major peak of conductance at ~12 pS in cholesterol-containing membrane. Observed Ala-CDs and NDs-induced increase in transmembrane current coincides with disturbance of excitatory and inhibitory neurotransmitter transport in nerve terminals.

Air pollution particulate matter as a potential carrier of SARS-CoV-2 to the nervous system and/or neurological symptom enhancer: arguments in favor

Entry receptor for SARS-CoV-2 is expressed in nasal epithelial cells, and nasal delivery pathway can be a key feature of transmission. Here, a possibility of interaction of SARS-CoV-2 with air pollution particulate matter (PM) was considered. It was shown in our recent studies that water-suspended plastic and wood smoke aerosol PM and carbon-containing nanoparticles from burning organics can interact with the plasma membrane of brain nerve terminals presumably due to their lipid components. COVID-19 patients have neurological symptoms, viral particles were found in the brain, SARS-CoV-2 enters the cells via fusion of lipid viral envelope with the plasma membranes of infected cells, and so viral envelop can contain lipid components of the host neuronal membranes. Therefore, interaction of SARS-CoV-2 envelope with PM is possible in water surrounding. After drying, PM can serve as a carrier for transmission of SARS-CoV-2 immobilized at their surface. Moreover, PM and SARS-CoV-2 per se can enter human organism during nasal inhalation, and they both use the same nose-to-brain delivery pathways moving along axons directly to the brain, influencing the nervous system and exocytosis/endocytosis in nerve cells. Thus, PM can aggravate neurological symptoms of SARS-CoV-2 and vice versa, due to their identical nose-to-brain delivery mechanism and possible interference of neuronal effects. In addition, different types of PM because of their ability to interact with the plasma membranes of nerve cells can facilitate unspecific SARS-CoV-2 entrance to the cells, and can influence envelope features of SARS-CoV-2. Detailed studies are required to analyze interaction of SARS-CoV-2 with PM.

Micro- and Nanosized Substances Cause Different Autophagy-Related Responses

With rapid industrialization, humans produce an increasing number of products. The composition of these products is usually decomposed. However, some substances are not easily broken down and gradually become environmental pollutants. In addition, these substances may cause bioaccumulation, since the substances can be fragmented into micro- and nanoparticles. These particles or their interactions with other toxic matter circulate in humans via the food chain or air. Whether these micro- and nanoparticles interfere with extracellular vesicles (EVs) due to their similar sizes is unclear. Micro- and nanoparticles (MSs and NSs) induce several cell responses and are engulfed by cells depending on their size, for example, particulate matter with a diameter ≤2.5 μm (PM2.5). Autophagy is a mechanism by which pathogens are destroyed in cells. Some artificial materials are not easily decomposed in organisms. How do these cells or tissues respond? In addition, autophagy operates through two pathways (increasing cell death or cell survival) in tumorigenesis. Many MSs and NSs have been found that induce autophagy in various cells and tissues. As a result, this review focuses on how these particles interfere with cells and tissues. Here, we review MSs, NSs, and PM2.5, which result in different autophagy-related responses in various tissues or cells.

GABAA receptor agonist cinazepam and its active metabolite 3-hydroxyphenazepam act differently at the presynaptic site

Cinazepam C₁₉H₁₄BrClN₂O₅, ("Levana^Ⓡ ІC") a partial GABA_A receptor agonist, and its active metabolite 3-hydroxyphenazepam C₁₅H₁₀BrClN₂O₂ were comparatively assessed in vitro using nerve terminals isolated from rat cortex (synaptosomes). At the presynaptic site, cinazepam (100 and 200 µM) facilitated synaptosomal transporter-mediated [³H]GABA uptake by enhancing both the initial rate and accumulation, and decreased the ambient level and transporter-mediated release of [³H]GABA. Whereas, 3-hydroxyphenazepam decreased the uptake and did not change the ambient synaptosomal level and transporter-mediated release of [³H]GABA. To exclude GABA transporter influence, NO-711, the transporter blocker, was applied and it was found that exocytotic release of [³H]GABA decreased, whereas tonic release of [³H]GABA was not changed in the presence of both cinazepam or 3-hydroxyphenazepam after treatment of synaptosomes with NO-711. In fluorimetric studies using potential- and pH-sensitive dyes rhodamine 6G and acridine orange, respectively, it was found that cinazepam hyperpolarized the synaptosomal plasma membrane, and increased synaptic vesicle acidification, whereas, 3-hydroxyphenazepam demonstrated opposite effects on these parameters. Therefore, action of cinazepam and its active metabolite 3-hydroxyphenazepam on GABAergic neurotransmission was different. Therapeutic effects of cinazepam can be associated with its ability to hyperpolarize the plasma membrane, to increase synaptic vesicle acidification and capacity of its active metabolite 3-hydroxyphenazepam to inhibit GABA transporter functioning.

Unique features of brain metastases-targeted AGuIX nanoparticles vs their constituents: A focus on glutamate-/GABA-ergic neurotransmission in cortex nerve terminals

Gadolinium-based radiosensitizing AGuIX nanoparticles (AGuIX) currently tested two phase 2 clinical trials in association with radiotherapy for the treatment of brain metastases. Here, excitatory/inhibitory neurotransmission was assessed in rat cortex nerve terminals in the presence of AGuIX and their constituents (DOTAGA and DOTAGA/Gd³⁺) at concentrations used for medical treatment, and those 5-24 times higher. The ambient level, transporter-mediated, tonic and exocytotic release of L-[¹⁴C]glutamate and [³H]GABA, the membrane potential of nerve terminals were not changed in the presence of AGuIX at concentrations used for medical treatment ([Gd³⁺] = 0.25 mM, corresponding to 0.25 g.L^-1), and DOTAGA (0.25 mM) and DOTAGA/Gd³⁺ (0.25 mM/0.01 mM). Difference between AGuIX and the precursors was uncovered, when their concentrations were increased. AGuIX (1.25-6 mM) did not change any transport characteristics of L-[¹⁴C]glutamate and [³H]GABA, whereas, DOTAGA (1.25-6 mM) affected the membrane potential, ambient level, and exocytotic release of L-[¹⁴C]glutamate and [³H]GABA. Gd³⁺ did not mask, but even enhanced above effects of DOTAGA. Therefore, AGuIX did not influence glutamate- and GABA-ergic neurotransmission at the presynaptic site. In contrast, DOTAGA and mixture DOTAGA/Gd³⁺ significantly affected synaptic neurotransmission at high concentrations. AGuIX own structure that overcomes neurotoxic features of their constituents.

Birds and plastic pollution: recent advances

Plastic waste and debris have caused substantial environmental pollution globally in the past decades, and they have been accumulated in hundreds of terrestrial and aquatic avian species. Birds are susceptible and vulnerable to external environments; therefore, they could be used to estimate the negative effects of environmental pollution. In this review, we summarize the effects of macroplastics, microplastics, and plastic-derived additives and plastic-absorbed chemicals on birds. First, macroplastics and microplastics accumulate in different tissues of various aquatic and terrestrial birds, suggesting that birds could suffer from the macroplastics and microplastics-associated contaminants in the aquatic and terrestrial environments. Second, the detrimental effects of macroplastics and microplastics, and their derived additives and absorbed chemicals on the individual survival, growth and development, reproductive output, and physiology, are summarized in different birds, as well as the known toxicological mechanisms of plastics in laboratory model mammals. Finally, we identify that human commensal birds, long-life-span birds, and model bird species could be utilized to different research objectives to evaluate plastic pollution burden and toxicological effects of chronic plastic exposure.

Inhibition of sigma-1 receptors substantially modulates GABA and glutamate transport in presynaptic nerve terminals

Sigma-1 receptors (Sig-1Rs) have been implicated in many neurological and psychiatric disorders and are a novel target for the treatment of such disorders. Sig-1R expression/activity deficits are linked to neurodegeneration, whereas the mechanisms mediated by Sig-1R are still unclear. Here, presynaptic [3H]GABA and L-[14C]glutamate transport was analysed in rat brain nerve terminals (synaptosomes) in the presence of the Sig-1R antagonist NE-100. NE-100 at doses of 1 and 10 μM increased the initial rate of synaptosomal [3H]GABA uptake, whereas 50 and 100 μM NE-100 decreased this rate, exerting a biphasic mode of action.Antagonists of GABAA and GABAB receptors, flumazenil and saclofen, respectively, prevented an increase in [3H]GABA uptake caused by 10 μM NE-100. L-[14C]glutamate uptake was decreased by 10-100 μM NE-100. A decrease in the uptake of both neurotransmitters mediated by NE-100 (50-100 μM) may have resulted from simultaneous antagonist-induced membrane depolarization, which was measured using the potential-sensitive fluorescent dye rhodamine 6G. The extracellular level of [3H]GABA was decreased by 1-10 μM NE-100, but that of L-[14C]glutamate remained unchanged. The tonic release of [3H]GABA measured in the presence of NO-711 was not changed by the antagonist, suggesting that NE-100 did not disrupt membrane integrity. The KCl- and FCCP-induced transporter-mediated release of L-[14C]glutamate was decreased by the antagonist; this may underlie the neuroprotective action of the antagonist in hypoxia/ischaemia. NE-100 (10-100 μM) decreased the KCl-evoked exocytotic release of [3H]GABA and L-[14C]glutamate, whereas the induction of the release of both neurotransmitters by the Ca2+ ionophore ionomycin was not affected by the antagonist; therefore, the mitigation of KCl-evoked exocytosis was associated with the NE-100-induced dysfunction of potential-dependent Ca2+ channels. Therefore, the Sig-1R antagonist can specifically act in an acute manner at the presynaptic level through the modulation of GABA and glutamate uptake, transporter-mediated release and exocytosis.

Transient coating of γ-Fe2O3 nanoparticles with glutamate for its delivery to and removal from brain nerve terminals

Glutamate is the main excitatory neurotransmitter in the central nervous system and excessive extracellular glutamate concentration is a characteristic feature of stroke, brain trauma, and epilepsy. Also, glutamate is a potential tumor growth factor. Using radiolabeled ʟ-[¹⁴C]glutamate and magnetic fields, we developed an approach for monitoring the biomolecular coating (biocoating) with glutamate of the surface of maghemite (γ-Fe₂O₃) nanoparticles. The nanoparticles decreased the initial rate of ʟ-[¹⁴C]glutamate uptake, and increased the ambient level of ʟ-[¹⁴C]glutamate in isolated cortex nerve terminals (synaptosomes). The nanoparticles exhibit a high capability to adsorb glutamate/ʟ-[¹⁴C]glutamate in water. Some components of the incubation medium of nerve terminals, that is, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and NaH₂PO₄, decreased the ability of γ-Fe₂O₃ nanoparticles to form a glutamate biocoating by about 50% and 90%, respectively. Only 15% of the amount of glutamate biocoating obtained in water was obtained in blood plasma. Albumin did not prevent the formation of a glutamate biocoating. It was shown that the glutamate biocoating is a temporal dynamic structure at the surface of γ-Fe₂O₃ nanoparticles. Also, components of the nerve terminal incubation medium and physiological fluids responsible for the desorption of glutamate were identified. Glutamate-coated γ-Fe₂O₃ nanoparticles can be used for glutamate delivery to the nervous system or for glutamate adsorption (but with lower effectiveness) in stroke, brain trauma, epilepsy, and cancer treatment following by its subsequent removal using a magnetic field. γ-Fe₂O₃ nanoparticles with transient glutamate biocoating can be useful for multifunctional theranostics.

Plastic smoke aerosol: Nano-sized particle distribution, absorption/fluorescent properties, dysregulation of oxidative processes and synaptic transmission in rat brain nerve terminals

Smoke from plastic waste incineration in an open air travels worldwide and is a major source of air pollution particulate matter (PM) that is very withstand to degradation and hazard to human health. Suspension of smoke aerosol components in water occurs during rains and fire extinguishing. Here, water-suspended plastic smoke aerosol (WPS) preparations suitable for biotesting were synthesized. It has been revealed using dynamic light scattering that WPS contained major nano-sized (∼30 nm) PM fraction, and this result was confirmed by electron microscopy. Optical absorption of WPS was in the UV region and an increase in λ_ex led to a red-shift in fluorescence emission with a corresponding decrease in fluorescence intensity. WPS was analyzed in neurotoxicity studies in vitro using presynaptic rat cortex nerve terminals (synaptosomes). Generation of spontaneous reactive oxygen species (ROS) detected using fluorescent dye 2',7-dichlorofluorescein in nerve terminals was decreased by WPS (10-50 μg/ml) in a dose-dependent manner. WPS also reduced the H₂O₂-evoked ROS production in synaptosomes, thereby influencing cellular oxidative processes and this effect was similar to that for carbon nanodots. WPS (0.1 mg/ml) decreased the synaptosomal membrane potential and synaptic vesicle acidification in fluorimetric experiments. WPS (1.0 mg/ml) attenuated the synaptosomal transporter-mediated uptake of excitatory and inhibitory neurotransmitters, L-[¹⁴C]glutamate and [³H]GABA, respectively. This can lead to an excessive increase in the glutamate concentration in the synaptic cleft and neurotoxicity via over activation of ionotropic glutamate receptors. Therefore, WPS was neurotoxic and provoked presynaptic malfunction through changes of oxidative activity, reduction of the membrane potential, synaptic vesicle acidification, and transporter-mediated uptake of excitatory and inhibitory neurotransmitters in nerve terminals. In summary, synthesis and emission to the environment of ultrafine PM occur during combustion of plastics, thereby polluting air and water resources, and possibly triggering development of neuropathologies.

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.

Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis

Air pollution is a modifiable and preventable factor, and it is a possible risk factor for dementia. However, evidence from epidemiological studies is still limited. We conducted a systematic review and meta-analysis to summarize the epidemiological evidence for long-term effects of particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5) on dementia/Alzheimer's disease (AD). Our inclusion criteria for eligible studies were: longitudinal cohort study design, no overlap in study population, age of study subject ≥50 years, detailed description of exposure assessment for PM_2.5, outdoor assessment of exposure to PM_2.5, usage of a clear definition of dementia/AD, and accessibility of sufficient information for meta-analysis. Six databases were searched for eligible studies. The random-effect model was used to synthesize the associations between PM_2.5 and dementia. After exclusion of all irrelevant studies, we analyzed the results of four cohort studies conducted in Canada, Taiwan, the UK, and the US during 2015-2018 among more than 12 million elderly subjects aged ≥50 years (N = 12,119,853). Our meta-analysis reveals that exposure to a 10 μg/m³ increase in PM_2.5 was significantly and positively associated with dementia (pooled HR = 3.26, 95% CI: 1.20, 5.31). In subgroup analyses, exposure to a 10 μg/m³ increase in PM_2.5 was found to be positively associated with AD (pooled HR = 4.82, 95% CI: 2.28, 7.36). Analysis of current epidemiological research on PM_2.5 and dementia confirmed that exposure to PM_2.5 was positively associated with a higher risk for dementia. However, it is to be noted that the included studies mainly relied on claim-based diagnosis and showed large differences in methods of exposure assessment, hence further epidemiological studies with well validated outcomes and with standardized exposure assessment models are required to ascertain the relationship between PM_2.5 and dementia/AD.

Respiratory gases, air pollution and epilepsy

A growing number of studies have shown that exposure to air pollutants such as particulate matter and gases can cause cardiovascular, neurodegenerative and psychiatric diseases. The severity of the changes depends on several factors such as exposure time, age and gender. Inflammation has been considered as one of the main factors associated with the generation of these diseases. Here we present some cellular mechanisms activated by air pollution that may represent risk factors for epilepsy and drug resistance associated to epilepsy.

Age-Dependency of Levetiracetam Effects on Exocytotic GABA Release from Nerve Terminals in the Hippocampus and Cortex in Norm and After Perinatal Hypoxia

Perinatal hypoxia can lead to multiple chronic neurological deficits, e.g., mental retardation, behavioral abnormalities, and epilepsy. Levetiracetam (LEV), 2S-(2-oxo-1-pyrrolidiny1) butanamide, is an anticonvulsant drug with proven efficiency in treating patients with focal and generalized seizures. Rats were underwent hypoxia and seizures at the age of 10-12 postnatal days (pd). The ambient level and depolarization-induced exocytotic release of [³H]GABA (γ-aminobutyric acid) were analyzed in nerve terminals in the hippocampus and cortex during development at the age of pd 17-19 and pd 24-26 (infantile stage), pd 38-40 (puberty) and pd 66-73 (young adults) in norm and after perinatal hypoxia. LEV had no effects on the ambient [³H]GABA level. The latter increased during development and was further elevated after perinatal hypoxia in nerve terminals in the hippocampus during the whole period and in the cortex in young adults. Exocytotic [³H]GABA release from nerve terminals increased after perinatal hypoxia during development in the hippocampus and cortex, however this effect was preserved at all ages during blockage of GABA transporters by NO-711 in the hippocampus only. LEV realized its anticonvulsant effects at the presynaptic site through an increase in exocytotic release of GABA. LEV exerted more significant effect after perinatal hypoxia than in norm. Action of LEV was strongly age-dependent and can be registered in puberty and young adults, but the drug was inert at the infantile stage.

EDTA Chelation Therapy for the Treatment of Neurotoxicity

Neurotoxicity can be caused by numerous direct agents, of which toxic metals, organophosphorus pesticides, air pollution, radiation and electromagnetic fields, neurotoxins, chemotherapeutic and anesthetic drugs, and pathogens are the most important. Other indirect causes of neurotoxicity are cytokine and/or reactive oxygen species production and adoptive immunotherapy. The development of neurodegenerative diseases has been associated with neurotoxicity. Which arms are useful to prevent or eliminate neurotoxicity? The chelating agent calcium disodium ethylenediaminetetraacetic acid (EDTA)-previously used to treat cardiovascular diseases-is known to be useful for the treatment of neurodegenerative diseases. This review describes how EDTA functions as a therapeutic agent for these diseases. Some case studies are reported to confirm our findings.

Express assessment of neurotoxicity of particles of planetary and interstellar dust

Establishment of high-quality, consistent on-board assessment of the neurotoxicity of planetary, and interstellar dust particles will be required to predict their potential threat to human health during long-term space missions. This Perspective article proposes an approach for the rapid assessment of potential neurotoxicity of micro-sized and nano-sized dust particles based on experimental results with other neurotoxic particles. Capacity of particles to affect membrane potential, integrity of nerve terminals, and consequently key synaptic transmission characteristics can be assessed using a planar lipid bilayer technique by monitoring artificial membrane conductivity in the presence of particles. Preliminary neurotoxicity data of nanoparticles, including lunar and Martian dust simulants, obtained using a planar lipid bilayer technique, is compared with that acquired using more-established methodological approaches. Under space flight conditions, neurotoxicity assessments of particulate matter could be rapidly and reproducibly performed using a planar lipid bilayer technique, which does not require biological material.

Vitamin D3 deficiency in puberty rats causes presynaptic malfunctioning through alterations in exocytotic release and uptake of glutamate/GABA and expression of EAAC-1/GAT-3 transporters

Recent experimental and epidemiologic investigations have revealed that the central nervous system is a target for vitamin D3 action and also linked vitamin D3 deficiency to Alzheimer's and Parkinson's disease, autism and dementia. Abnormal homeostasis of glutamate and GABA and signaling disbalance are implicated in the pathogenesis of major neurological diseases. Here, key transport characteristics of glutamate and GABA were analysed in presynaptic nerve terminals (synaptosomes) isolated from the cortex of vitamin D3 deficient (VDD) rats. Puberty rats were kept at the VDD diet up to adulthood. VDD caused: (i) a decrease in the initial rates of L-[¹⁴C]glutamate and [³H]GABA uptake by plasma membrane transporters of nerve terminals; (ii) a decrease in exocytotic release of L-[¹⁴C]glutamate and [³H]GABA; (iii) changes in expression of glutamate (EAAC-1) and GABA (GAT-3) transporters. Whereas, the synaptosomal ambient levels and Ca²⁺-independent transporter-mediated release of L-[¹⁴C]glutamate and [³H]GABA were not significantly altered in VDD. Vitamin D3 is a potent neurosteroid and its nutritional deficiency can provoke development of neurological consequences changing glutamate/GABA transporter expressions and excitation/inhibition balance. Also, changes in glutamate transport can underlie lower resistance to hypoxia/ischemia, larger infarct volumes and worsened outcomes in ischemic stroke patients with VDD.

Levetiracetam-mediated improvement of decreased NMDA-induced glutamate release from nerve terminals during hypothermia

A combination of a beneficial neuroprotectant, hypothermia, with targeted medication is a perspective therapeutic approach. Here, we analyzed both non-specific (deep and profound hypothermia, 27 °C and 17 °C, respectively) and targeted (anticonvulsant drug levetiracetam) modulation of l-[¹⁴C]glutamate release induced by activation of presynaptic NMDA, AMPA, and kainate receptors in rat brain nerve terminals (synaptosomes). Gradual dynamics of hypothermia-mediated decrease in synaptosomal l-[¹⁴C]glutamate release evoked by the receptor agonists NMDA-, AMPA-, and kainate (250 μM) has been demonstrated that can be of value for the justification of optimal temperature regimes in therapeutic hypothermia. 250 μM NMDA-induced l-[¹⁴C]glutamate release from nerve terminals was higher in the presence of levetiracetam (100 μM) as compared to that without the drug. Despite levetiracetam effects decreased in hypothermia, combined application of hypothermia and levetiracetam resulted in higher NMDA-induced l-[¹⁴C]glutamate release from nerve terminals as compared to that without the drug. These effects were not revealed for synaptosomal AMPA- and kainate-induced l-[¹⁴C]glutamate release in the presence of levetiracetam at the similar concentration. Therefore, levetiracetam administration significantly mitigated a hypothermia-induced decrease in NMDA receptor response at the presynaptic level and can be used for the targeted neurocorrection to reduce side effects of hypothermia in cardiac surgery. However, levetiracetam-mediated improvement of NMDA receptor response is not applicable in stroke, brain trauma and neonatal asphyxia therapies, where the main neuroprotective action of hypothermia is associated with prevention of damaging consequence of pre-existing acute glutamate exitotoxicity.