Toxic effects of environmental-relevant exposure to polyethylene terephthalate (PET) micro and nanoparticles in zebrafish early development.

Polyethylene terephthalate (PET) is a commonly used thermoplastic in industry due to its excellent malleability and thermal stability, making it extensively employed in packaging manufacturing. Inadequate disposal of PET packaging in the environment and natural physical-chemical processes leads to the formation of smaller particles known as PET micro and nanoplastics (MNPs). The reduced dimensions enhance particle bioavailability and, subsequently, their reactivity. This study involved chemical degradation of PET using trifluoroacetic acid to assess the impact of exposure to varying concentrations of PET MNPs (0.5, 1, 5, 10, and 20 mg/L) on morphological, functional, behavioral, and biochemical parameters during the early developmental stages of zebrafish (Danio rerio). Characterization of the degraded PET revealed the generated microplastics (MPs) ranged in size from 1305 to 2032 µm, and that the generated nanoplastics (NPs) ranged from 68.06 to 955 nm. These particles were then used for animal exposure. After a six-day exposure period, our findings indicate that PET MNPs can diminish spontaneous tail coiling (STC), elevate the heart rate, accumulate on the chorion surface, and reduce interocular distance. These results suggest that PET exposure induces primary toxic effects on zebrafish embryo-larval stage of development.

A high fat diet potentiates neonatal iron overload-induced memory impairments in rats.

PURPOSE: The present study aimed at evaluating possible synergistic effects between two risk factors for cognitive decline and neurodegenerative disorders, i.e. iron overload and exposure to a hypercaloric/hyperlipidic diet, on cognition, insulin resistance, and hippocampal GLUT1, GLUT3, Insr mRNA expression, and AKT phosporylation. METHODS: Male Wistar rats were treated with iron (30 mg/kg carbonyl iron) or vehicle (5% sorbitol in water) from 12 to 14th post-natal days. Iron-treated rats received a standard laboratory diet or a high fat diet from weaning to adulthood (9 months of age). Recognition and emotional memory, peripheral blood glucose and insulin levels were evaluated. Glucose transporters (GLUT 1 and GLUT3) and insulin signaling were analyzed in the hippocampus of rats. RESULTS: Both iron overload and exposure to a high fat diet induced memory deficits. Remarkably, the association of iron with the high fat diet induced more severe cognitive deficits. Iron overload in the neonatal period induced higher insulin levels associated with significantly higher HOMA-IR, an index of insulin resistance. Long-term exposure to a high fat diet resulted in higher fasting glucose levels. Iron treatment induced changes in Insr and GLUT1 expression in the hippocampus. At the level of intracellular signaling, both iron treatment and the high fat diet decreased AKT phosphorylation. CONCLUSION: The combination of iron overload with exposure to a high fat diet only led to synergistic deleterious effect on emotional memory, while the effects induced by iron and by the high fat diet on AKT phosphorylation were comparable. These findings indicate that there is, at least to some extent, an additive effect of iron combined with the diet. Further studies investigating the mechanisms associated to deleterious effects on cognition and susceptibility for the development of age-associated neurodegenerative disorders are warranted.

Locomotor Behavior and Memory Dysfunction Induced by 3-Nitropropionic Acid in Adult Zebrafish: Modulation of Dopaminergic Signaling.

Huntington's disease (HD) is a progressive neurodegenerative disease characterized by neuropsychiatric disturbance, cognitive impairment, and locomotor dysfunction. In the early stage (chorea) of HD, expression of dopamine D2 receptors (D2R) is reduced, whereas dopamine (DA) levels are increased. Contrary, in the late stage (bradykinesia), DA levels and the expression of D2R and dopamine D1 receptors (D1R) are reduced. 3-Nitropropionic acid (3-NPA) is a toxin that may replicate HD behavioral phenotypes and biochemical aspects. This study assessed the neurotransmitter levels, dopamine receptor gene expression, and the effect of acute exposure to quinpirole (D2R agonist) and eticlopride (D2R antagonist) in an HD model induced by 3-NPA in adult zebrafish. Quinpirole and eticlopride were acutely applied by i.p. injection in adult zebrafish after chronic treatment of 3-NPA (60 mg/kg). 3-NPA treatment caused a reduction in DA, glutamate, and serotonin levels. Quinpirole reversed the bradykinesia and memory loss induced by 3-NPA. Together, these data showed that 3-NPA acts on the dopaminergic system and causes biochemical alterations similar to late-stage HD. These data reinforce the hypothesis that DA levels are linked with locomotor and memory deficits. Thus, these findings may suggest that the use of DA agonists could be a pharmacological strategy to improve the bradykinesia and memory deficits in the late-stage HD.

Effect of adenosine treatment on ionizing radiation toxicity in zebrafish early life stages.

The danger of ionizing radiation exposure to human health is a concern. Since its wide use in medicine and industry, the development of radioprotectors has been very significant. Adenosine exerts anti-inflammatory actions and promotes tissue protection and repair, by activating the P1 receptors (A1, A2A, A2B, and A3). Zebrafish (Danio rerio) is an appropriate tool in the fields of toxicology and pharmacology, including the evaluation of radiobiological outcomes and in the search for radioprotector agents. This study aims to evaluate the effect of adenosine in the toxicity induced by radiation in zebrafish. Embryos were treated with 1, 10, or 100 µM adenosine, 30 min before the exposure to 15 Gy of gamma radiation. Adenosine potentiated the effects of radiation in heart rate, body length, and pericardial edema. We evaluated oxidative stress, tissue remodeling and inflammatory. It was seen that 100 µM adenosine reversed the inflammation induced by radiation, and that A2A2 and A2B receptors are involved in these anti-inflammatory effects. Our results indicate that P1R activation could be a promising pharmacological strategy for radioprotection.

Micro- and nanoplastic toxicity: A review on size, type, source, and test-organism implications.

Polymeric wastes are among the current major environmental problems due to potential pollution and contamination. Within the spectrum of polymeric waste, microplastics (MPs) and nanoplastics (NPs) have gained ground in recent research since these particles can affect the local biota, inducing toxic effects on several organisms. Different outcomes have been reported depending on particle sizes, shape, types, and exposed organisms and conditions, among other variables. This review aimed to compile and discuss the current knowledge and possible literature gaps regarding the MPs and NPs generation and their toxicological effects as stressors, considering polymer type (as polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, or others), size (micro- or nano-scale), source (commercial, lab-synthesized, or environmental) and test organism group. In that sense, 615 publications were analyzed, among which 72 % discussed micro-sized plastics, while <28 % assayed the toxicity of NPs (<1 µm). For most polymers, MPs and NPs were commercially purchased and used without additional size reduction processes; except for polyethylene terephthalate studies that mostly used grinding and cutting methods to obtain MPs. Polystyrene (PS) was the main polymer studied, as both MPs and NPs. PS accounts for >90 % of NPs reports evaluated, reflecting a major literature gap if compared to its 35.3 % share on MPs studies. Among the main organisms, arthropods and fish combined accounted for nearly 40 % of toxicity testing. Overall, the different types of plastics showed a tendency to report toxic effects, except for the 'Survival/lethality' category, which might indicate that polymeric particles induce mostly sublethal toxic effects. Furthermore, despite differences in publication numbers, we observed greater toxicity reported for NPs than MPs with oxidative stress among the majorly investigated endpoints. This study allowed a hazard profile overview of micro/nanoplastics (MNPs) and the visualization of literature gaps, under a broad diversity of toxicological evidence.

P2Y12 receptor antagonism inhibits proliferation, migration and leads to autophagy of glioblastoma cells.

Glioblastoma (GBM) is the most aggressive and lethal among the primary brain tumors, with a low survival rate and resistance to radio and chemotherapy. The P2Y12 is an adenosine diphosphate (ADP) purinergic chemoreceptor, found mainly in platelets. In cancer cells, its activation has been described to induce proliferation and metastasis. Bearing in mind the need to find new treatments for GBM, this study aimed to investigate the role of the P2Y12R in the proliferation and migration of GBM cells, as well as to evaluate the expression of this receptor in patients' data obtained from the TCGA data bank. Here, we used the P2Y12R antagonist, ticagrelor, which belongs to the antiplatelet agent's class. The different GBM cells (cell line and patient-derived cells) were treated with ticagrelor, with the agonist, ADP, or both, and the effects on cell proliferation, colony formation, ADP hydrolysis, cell cycle and death, migration, and cell adhesion were analyzed. The results showed that ticagrelor decreased the viability and the proliferation of GBM cells. P2Y12R antagonism also reduced colony formation and migration potentials, with alterations on the expression of metalloproteinases, and induced autophagy in GBM cells. Changes were observed at the cell cycle level, and only the U251 cell line showed a significant reduction in the ADP hydrolysis profile. TCGA data analysis showed a higher expression of P2Y12R in gliomas samples when compared to the other tumors. These data demonstrate the importance of the P2Y12 receptor in gliomas development and reinforce its potential as a pharmacological target for glioma treatment.

Participation of ecto-5'-nucleotidase in the inflammatory response in an adult zebrafish (Danio rerio) model.

The ecto-5'-nucleotidase is an important source of adenosine in the extracellular medium. Adenosine modulation appears early in evolution and performs several biological functions, including a role as an anti-inflammatory molecule. Here, we evaluate the activity and mRNA expression of ecto-5'-nucleotidase in response to lipopolysaccharide (LPS) using zebrafish as a model. Adult zebrafish were injected with LPS (10 µg/g). White blood cell differential counts, inflammatory markers, and ecto-5'-nucleotidase activity and expression in the encephalon, kidney, heart, and intestine were evaluated at 2, 12, and 24 h post-injection (hpi). At 2 hpi of LPS, an increase in neutrophils and monocytes in peripheral blood was observed, which was accompanied by increased tnf-α expression in the heart, kidney, and encephalon, and increased cox-2 expression in the intestine and kidney. At 12 hpi, monocytes remained elevated in the peripheral blood, while tnf-α expression was also increased in the intestine. At 24 hpi, the white blood cell differential count no longer differed from that of the control, whereas tnf-α expression remained elevated in the encephalon but reduced in the kidney compared with the controls. AMP hydrolysis in LPS-treated animals was increased in the heart at 24 hpi [72 %; p = 0.029] without affecting ecto-5'-nucleotidase gene expression. These data indicate that, in most tissues studied, inflammation does not affect ecto-5'-nucleotidase activity, whereas in the heart, a delayed increase in ecto-5'-nucleotidase activity could be related to tissue repair.

Modulation of adenosine signaling reverses 3-nitropropionic acid-induced bradykinesia and memory impairment in adult zebrafish.

Huntington's disease (HD) is a neurodegenerative disorder, characterized by motor dysfunction, psychiatric disturbance, and cognitive decline. In the early stage of HD, occurs a decrease in dopamine D2 receptors and adenosine A2A receptors (A2AR), while in the late stage also occurs a decrease in dopamine D1 receptors and adenosine A1 receptors (A1R). Adenosine exhibits neuromodulatory and neuroprotective effects in the brain and is involved in motor control and memory function. 3-Nitropropionic acid (3-NPA), a toxin derived from plants and fungi, may reproduce HD behavioral phenotypes and biochemical characteristics. This study investigated the effects of acute exposure to CPA (A1R agonist), CGS 21680 (A2AR agonist), caffeine (non-selective of A1R and A2AR antagonist), ZM 241385 (A2AR antagonist), DPCPX (A1R antagonist), dipyridamole (inhibitor of nucleoside transporters) and EHNA (inhibitor of adenosine deaminase) in an HD pharmacological model induced by 3-NPA in adult zebrafish. CPA, CGS 21680, caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA were acutely administered via i.p. in zebrafish after 3-NPA (at dose 60 mg/kg) chronic treatment. Caffeine and ZM 241385 reversed the bradykinesia induced by 3-NPA, while CGS 21680 potentiated the bradykinesia caused by 3-NPA. Moreover, CPA, caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA reversed the 3-NPA-induced memory impairment. Together, these data support the hypothesis that A2AR antagonists have an essential role in modulating locomotor function, whereas the activation of A1R and blockade of A2AR and A1R and modulation of adenosine levels may reduce the memory impairment, which could be a potential pharmacological strategy against late-stage symptoms HD.

Inhibition of ATP hydrolysis as a key regulator of temozolomide resistance and migratory phenotype of glioblastoma cells.

Glioblastoma (GBM) is the most lethal among malignant gliomas. The tumor invasiveness and therapy-resistance are important clinical hallmarks. Growing evidence emphasizes the purinergic signaling contributing to tumor growth. Here we exposed a potential role of extracellular ATPase activity as a key regulator of temozolomide cytotoxicity and the migration process in GBM cells. The inhibition of ATP hydrolysis was able to improve the impact of temozolomide, causing arrest mainly in S and G2 phases of the cell cycle, leading M059J and U251 cells to apoptosis. In addition to eradicating GBM cells, ATP hydrolysis exhibited a potential to modulate the invasive phenotype and the expression of proteins involved in cell migration and epithelial-to-mesenchymal-like transition in a 3D culture model. Finally, we suggest the ATPase activity as a key target to decline temozolomide resistance and the migratory phenotype in GBM cells.

Acute toxicity of methomyl commercial formulation induces morphological and behavioral changes in larval zebrafish (Danio rerio).

The use of pesticides has continue grown over recent years, leading to several environmental and health concerns, such as the contamination of surface and groundwater resources and associated biota, potentially affecting populations that are not primary targets of these complex chemical mixtures. In this work, we investigate lethal and sublethal effects of acute exposure of methomyl commercial formulation in zebrafish embryo and larvae. Methomyl is a broad-spectrum carbamate insecticide and acaricide that acts primarily in acetylcholinesterase inhibition (AChE). Methomyl formulation 96 h-LC50 was determined through the Fish Embryo Acute Toxicity Test (FET) and resulted in 1.2 g/L ± 0.04. Sublethal 6-day exposure was performed in six methomyl formulation concentrations (0.5; 1.0; 2.2; 4.8; 10.6; 23.3 mg/L) to evaluate developmental, physiological, morphological, behavioral, biochemical, and molecular endpoints of zebrafish early-development. Methomyl affected embryo hatching and larva morphology and behavior, especially in higher concentrations; resulting in smaller body and eyes size, failure in swimming bladder inflation, hypolocomotor activity, and concentration-dependent reduction of AChE activity; demonstrating methomyl strong acute toxicity and neurotoxic effect.

Prolonged ethanol exposure alters glutamate uptake leading to astrogliosis and neuroinflammation in adult zebrafish brain.

High ethanol (EtOH) consumption is a serious condition that induces tremors, alcoholic psychosis, and delirium, being considered a public health problem worldwide. Prolonged EtOH exposure promotes neurodegeneration, affecting several neurotransmitter systems and transduction signaling pathways. Glutamate is the major excitatory amino acid in the central nervous system (CNS) and the extracellular glutamatergic tonus is controlled by glutamate transporters mostly located in astrocytes. Here, we explore the effects of prolonged EtOH exposure on the glutamatergic uptake system and its relationship with astroglial markers (GFAP and S100B), neuroinflammation (IL-1ß and TNF-α), and brain derived neurotrophic factor (BDNF) levels in the CNS of adult zebrafish. Animals were exposed to 0.5% EtOH for 7, 14, and 28 days continuously. Glutamate uptake was significantly decreased after 7 and 14 days of EtOH exposure, returning to baseline levels after 28 days of exposure. No alterations were observed in crucial enzymatic activities linked to glutamate uptake, like Na,K-ATPase or glutamine synthetase. Prolonged EtOH exposure increased GFAP, S100B, and TNF-α levels after 14 days. Additionally, increased BDNF mRNA levels were observed after 14 and 28 days of EtOH exposure, while BDNF protein levels increased only after 28 days. Collectively, our data show markedly brain astroglial, neuroinflammatory and neurotrofic responses after an initial impairment of glutamate uptake following prolonged EtOH exposure. This neuroplasticity event could play a key role in the modulatory effect of EtOH on glutamate uptake after 28 days of continuous exposure.

Effects of lipoic acid supplementation on age- and iron-induced memory impairment, mitochondrial DNA damage and antioxidant responses.

PURPOSE: To investigate the effects of lipoic acid (LA) supplementation during adulthood combined with supplementation later in life or LA administration only at old age on age-induced cognitive dysfunction, mitochondrial DNA deletions, caspase 3 and antioxidant response enzymes expression in iron-treated rats. METHODS: Male rats were submitted to iron treatment (30 mg/kg body wt of Carbonyl iron) from 12 to 14th post-natal days. Iron-treated rats received LA supplementation (50 mg/kg, daily) in adulthood and old age or at old age only for 21 days. Memory, mitochondrial DNA (mtDNA) complex I deletions, caspase 3 mRNA expression and antioxidant response enzymes mRNA expression were analyzed in the hippocampus. RESULTS: LA administration in adulthood combined with treatment later in life was able to reverse age-induced effects on object recognition and inhibitory avoidance memory, as well as on mtDNA deletions, nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression, and antioxidant enzymes disruption induced by iron in aged rats. LA treatment only at old age reversed iron-induced effects to a lesser extent when compared to the combined treatment. CONCLUSION: The present findings support the view that LA supplementation may be considered as an adjuvant against mitochondrial damage and cognitive decline related to aging and neurodegenerative disorders.

Co-exposure to nTiO2 impairs arsenic metabolism and affects antioxidant capacity in the marine shrimp Litopenaeus vannamei.

Aquatic animals are vulnerable to arsenic (As) toxicity. However, rarely does a contaminant occur alone in the aquatic environment. For this reason, this study was conducted to evaluate whether titanium dioxide nanoparticles (nTiO2) can interfere with the effects induced by As in Litopenaeus vannamei. Arsenic accumulation and metabolic capacity; expression and enzymatic activity of GSTΩ (glutathione-S-transferase omega isoform); antioxidant responses such as GSH, GR, and GST (reduced glutathione levels, glutathione reductase, and glutathione-S-transferase activity, respectively); and lipid peroxidation in the gills and hepatopancreas of shrimp were evaluated. The results are summarized as follows: (1) higher accumulation of As occurred in both tissues after exposure to As alone; (2) co-exposure to nTiO2 affected the capacity to metabolize As; (3) GSTΩ gene expression was not modified, but its activity was decreased by co-exposure to both contaminants; (4) As alone increased the GSH levels in the hepatopancreas, and co-exposure to nTiO2 reduced these levels in both tissues; (5) a decrease in the GST activity in the gills occurred with all treatments; (6) in the gills, GR activity was increased by As, and nTiO2 reversed this increase, whereas in the hepatopancreas co-exposure inhibited enzyme activity; (7) only in the hepatopancreas lipid damage was observed when animals were exposed to As or nTiO2 but not in co-exposure. The results showed that the As induces toxic effects in both tissues of shrimp and that co-exposure to nTiO2 can potentiate these effects and decrease the capacity to metabolize As, favoring the accumulation of more toxic compounds.

On the effects of iron ore tailings micro/nanoparticles in embryonic and larval zebrafish (Danio rerio).

Iron ore tailings (IOT) represent a major problem in the mining industry worldwide due to large volumes of waste disposed in mine sites. IOT are exposed to the environment and subjected to wind and water dispersion, even under non-catastrophic scenarios as dam collapses, and the effects of these particles to the biota are still mostly unknown. This work aimed to prepare and to characterize a suspension containing the finest (micro/nano range) particles of IOT and to evaluate its effects on development and behavior of zebrafish (Danio rerio), at both embryonic and larval stages. IOT suspension comprised 37 mg L-1 of a multi-mineral material mainly composed by hematite and quartz, in a size-range of 33-1400 nm. Regarding in vivo toxicological assays, no robust alterations were recorded in functional, morphological and behavioral end-points analyzed, although a significant adhesion of IOT particles on zebrafish chorion was observed, without a prejudice of embryo hatching. Under applied conditions, iron ore particles did not present harmful effects to the initial stages of zebrafish development, and the particle size range and potential interactions with SiO2 content might be behind such effect.

Antibiotic drugs alter zebrafish behavior.

Antibiotics are widely used drugs in human and veterinary health as well as in the food industry. The majority of these compounds are, however, excreted unchanged and found as contaminants in water bodies. Although the toxicity of these drugs was previously studied in aquatic organisms, the behavioral effects of these pollutants have not been fully explored. Here we exposed adult zebrafish to environmentally relevant concentrations of different classes of antibiotics (Chlortetracycline, Ciprofloxacin, and Ceftazidime) and assessed zebrafish exploratory, cognitive, aggressive, and social behaviors. Ciprofloxacin, Chlortetracycline, and Ceftazidime exposure induced hyperlocomotion, which was characterized by an increase in the distance traveled in zebrafish. These antibiotics promoted cognitive decline and exacerbated aggressive behavior. In summary, this study shows that antibiotic contamination may impact zebrafish behavior in a short-time manner.

Neural Regenerative Potential of Stem Cells Derived from the Tooth Apical Papilla.

The regenerative effects of stem cells derived from dental tissues have been previously investigated. This study assessed the potential of human tooth stem cells from apical papilla (SCAP) on nerve regeneration. The SCAP collected from nine individuals were characterized and polarized by exposure to interferon-γ (IFN-γ). IFN-γ increased kynurenine and interleukin-6 (IL-6) production by SCAP, without affecting the cell viability. IFN-γ-primed SCAP exhibited a decrease of brain-derived neurotrophic factor (BDNF) mRNA levels, followed by an upregulation of glial cell-derived neurotrophic factor mRNA. Ex vivo, the co-culture of SCAP with neurons isolated from the rat dorsal root ganglion induced neurite outgrowth, accompanied by increased BDNF secretion, irrespective of IFN-γ priming. In vivo, the local application of SCAP reduced the mechanical and thermal hypersensitivity in Wistar rats that had been submitted to sciatic chronic constriction injury. The SCAP also reduced the pain scores, according to the evaluation of the Grimace scale, partially restoring the myelin damage and BDNF immunopositivity secondary to nerve lesion. Altogether, our results provide novel evidence about the regenerative effects of human SCAP, indicating their potential to handle nerve injury-related complications.

Pyriproxyfen Exposure Impairs Cognitive Parameters and Alters Cortisol Levels in Zebrafish.

Pyriproxyfen is one of the most used larvicides and insecticides; it acts as an analog of juvenile insect hormone (a growth regulator). It is highly toxic during all stages of mosquito development, suppresses metamorphosis, and interferes in insect reproduction and proliferation. Pyriproxyfen and its main metabolite have been shown to affect brain development in rodents. This compound is employed mainly to eliminate outbreaks of the genus Aedes, even in potable water. Despite the increasing number of toxicological studies about larvicides and insecticides-with an indication of continuous use-there have been few studies about the effects of pyriproxyfen in non-target species such as fish. This study evaluated the effects of pyriproxyfen on behavioral, cognitive, and endocrine parameters in zebrafish. We exposed adult zebrafish to different pyriproxyfen (Pestanal®) concentrations (0.125, 0.675, and 1.75 mg/l) for 96 h. We analyzed behavioral parameters, memory, cortisol levels, and gene expression of glucocorticoid receptor (gr) and corticotrophin-releasing factor (crf) after pyriproxyfen exposure. This exposure did not alter locomotion (distance or mean speed), anxiety-like behavior (latency to enter to the top zone of the tank or time in the top zone of the tank), and social or aggressive behavior. However, there was impaired inhibitory avoidance memory at all tested pyriproxyfen concentrations. Cortisol levels were reduced in exposed groups when compared to control or vehicle. However, gr and crf gene expression in pyriproxyfen-treated animals were unaltered when compared to control or vehicle groups. Taken together, these findings indicate that pyriproxyfen may induce cognitive impairment and altered cortisol levels in zebrafish, a non-target species.

Graphene oxide and GST-omega enzyme: An interaction that affects arsenic metabolism in the shrimp Litopenaeus vannamei.

Arsenic (As) is one of the most widespread contaminants; it is found in almost every environment. Its toxic effects on living organisms have been studied for decades, but the interaction of this metalloid with other contaminants is still relatively unknown, mainly whether this interaction occurs with emerging contaminants such as nanomaterials. To examine this relationship, the marine shrimp Litopenaeus vannamei was exposed for 48 h to As, graphene oxide (GO; two different concentrations) or a combination of both, and gills, hepatopancreas and muscle tissues were sampled. Glutathione S-transferase (GST)-omega gene expression and activity were assessed. As accumulation and speciation (metabolisation capacity) were also examined. Finally, a molecular docking simulation was performed to verify the possible interaction between the nanomaterial and GST-omega. The main finding was that GO modulated the As toxic effect: it decreased GST-omega activity, a consequence related to altered As accumulation and metabolism. Besides, the molecular docking simulation confirmed the capacity of GO to interact with the enzyme structure, which also can be related to the decreased GST-omega activity and subsequently to the altered As accumulation and metabolisation pattern.

Characterization of the adenosinergic system in a zebrafish embryo radiotherapy model.

Adenosine is a nucleoside that acts as a signaling molecule by activating P1 purinergic receptors (A1, A2A, A2B and A3). This activation is involved in immune responses, inflammation, and tissue remodeling and tumor progression. Gamma rays are a type of ionizing radiation widely adopted in radiotherapy of tumors. Although it brings benefits to the success of the therapeutic scheme, it can trigger cellular damages, inducing a perpetual inflammatory response that culminates in adverse effects and severe toxicity. Our study aims to characterize the adenosinergic system in a zebrafish embryo radiotherapy model, relating the adenosine signaling to the changes elicited by radiation exposure. To standardize the radiotherapy procedure, we established a toxicological profile after exposure. Zebrafish were irradiated with different doses of gamma rays (2, 5, 10, 15 and 20 Gy) at 24 hpf. Survival, hatching rate, heartbeats, locomotor activity and morphological changes were determined during embryos development. Although without significant difference in survival, gamma-irradiated embryos had their heartbeats increased and presented decreased hatching time, changes in locomotor activity and important morphological alterations. The exposure to 10 Gy disrupted the ecto-5'-nucleotidase/CD73 and adenosine deaminase/ADA enzymatic activity, impairing adenosine metabolism. We also demonstrated that radiation decreased A2B receptor gene expression, suggesting the involvement of extracellular adenosine in the changes prompted by radiotherapy. Our results indicate that the components of the adenosinergic system may be potential targets to improve radiotherapy and manage the tissue damage and toxicity of ionizing radiation.

Nociceptin/orphanin FQ receptor modulates painful and fatigue symptoms in a mouse model of fibromyalgia.

Generalized pain and fatigue are both hallmarks of fibromyalgia, a syndrome with an indefinite etiology. The treatment options for fibromyalgia are currently limited, probably because of its intricate pathophysiology. Thus, further basic and clinical research on this condition is currently needed. This study investigated the effects of nociceptin/orphanin FQ (N/OFQ) receptor (NOPr) ligands and the modulation of the NOP system in the preclinical mouse model of reserpine-induced fibromyalgia. The effects of administration of the natural agonist N/OFQ and the selective NOPr antagonists (UFP-101 and SB-612111) were evaluated in fibromyalgia-related symptoms in reserpine-treated mice. The expression of prepronociceptin/orphanin FQ and NOPr was assessed in central and peripheral sites at different time points after reserpine administration. Nociceptin/orphanin FQ displayed dual effects in the behavioral changes in the reserpine-elicited fibromyalgia model. The peptide NOPr antagonist UFP-101 produced analgesic and antifatigue effects, by preventing alterations in brain activity and skeletal muscle metabolism, secondary to fibromyalgia induction. The nonpeptide NOPr antagonist SB-612111 mirrored the favorable effects of UFP-101 in painful and fatigue alterations induced by reserpine. A time-related up- or downregulation of prepronociceptin/orphanin FQ and NOPr was observed in supraspinal, spinal, and peripheral sites of reserpine-treated mice. Our data shed new lights on the mechanisms underlying the fibromyalgia pathogenesis, supporting a role for N/OFQ-NOP receptor system in this syndrome.