Caenorhabditis elegans as a model for studies on quinolinic acid-induced NMDAR-dependent glutamatergic disorders.

Quinolinic acid (QUIN) is an agonist of the neurotransmitter glutamate (Glu) capable of binding to N-methyl-D-aspartate receptors (NMDAR) increasing glutamatergic signaling. QUIN is known for being an endogenous neurotoxin, able to induce neurodegeneration. In Caenorhabditis elegans, the mechanism by which QUIN induces behavioral and metabolic toxicity has not been fully elucidated. The effects of QUIN on behavioral and metabolic parameters in nmr-1 and nmr-2 NMDA receptors in transgenic and wild-type (WT) worms were performed to decipher the pathway by which QUIN exerts its toxicity. QUIN increased locomotion parameters such as wavelength and movement amplitude medium, as well as speed and displacement, without modifying the number of body bends in an NMDAR-dependent-manner. QUIN increased the response time to the chemical stimulant 1-octanol, which is modulated by glutamatergic neurotransmission in the ASH neuron. Brood size increased after exposure to QUIN, dependent upon nmr-2/NMDA-receptor, with no change in lifespan. Oxygen consumption, mitochondrial membrane potential, and the flow of coupled and unbound electrons to ATP production were reduced by QUIN in wild-type animals, but did not alter citrate synthase activity, altering the functionality but the mitochondrial viability. Notably, QUIN modified fine locomotor and chemosensory behavioral parameters, as well as metabolic parameters, analogous to previously reported effects in mammals. Our results indicate that QUIN can be used as a neurotoxin to elicit glutamatergic dysfunction in C. elegans in a way analogous to other animal models.

N,N' bis-(2-mercaptoethyl) isophthalamide induces developmental delay in Caenorhabditis elegans by promoting DAF-16 nuclear localization.

N,N' bis-(2-mercaptoethyl) isophthalamide (NBMI) is a lipophilic thiol-containing agent that has high affinity for toxic metal ions, such as Hg2+, Pb2+, and Cd2+. Studies have shown that NBMI is a potent chelator of heavy metals, yet its potential toxicity in animals has yet to be determined. Using the model organism Caenorhabditis elegans (C. elegans), we show no significant change in worms' death rate or lifespan following NBMI treatment (10-1000 µM). However, NBMI treatment was associated with a significant developmental delay. To determine if the daf-2/age-1/daf-16 pathway is involved in NBMI toxicity, mRNA levels of these genes were assessed in worms treated with NBMI. Here, we found that while NBMI failed to significantly alter the expression of daf-16 or daf-2; age-1 was significantly downregulated by NBMI. Furthermore, NBMI significantly increased DAF-16 nuclear localization. Consistent with a role for this pathway in NBMI toxicity, the developmental arrest by NBMI was more prominent in the DAF-16 transgenic strain than in the wild type N2 strain. Moreover, in the mutant strains harboring null alleles of daf-16, NBMI had no effect on development. In addition, NBMI repressed the expression of detoxifying genes (skn-1, gst-4 and gcs-1). In summary, NBMI has a low developmental toxicity in the C. elegans model, and the nuclear translocation of DAF-16 is involved in the developmental effect of NBMI.

Simvastatin-loaded nanoemulsions: development, characterization, stability study and toxicity assays.

Aim: The aim of this study is to prepare and characterize simvastatin-loaded nanoemulsions (SIM-LN) as well as evaluate their physicochemical properties and toxicity. Methodology & results: The SIM-LN were prepared, their characteristics evaluated for 30 days, and after that, the SIM-LN toxicity was evaluated using Vero cell culture and the in vivo model of Caenorhabditis elegans. The prepared SIM-LN had an average droplet size of 139 ± 22 nm, with high encapsulation rate (>98.4%). The storage at room temperature proved to be the most optimal condition. Toxicity assays demonstrated no toxicity. Conclusion: It was demonstrated that the surfactants used as emulsifiers optimized the properties without side effects, because no toxicity was measured in preliminary tests.

The effects of manganese overexposure on brain health.

Manganese (Mn) is the twelfth most abundant element on the earth and an essential metal to human health. Mn is present at low concentrations in a variety of dietary sources, which provides adequate Mn content to sustain support various physiological processes in the human body. However, with the rise of Mn utility in a variety of industries, there is an increased risk of overexposure to this transition metal, which can have neurotoxic consequences. This risk includes occupational exposure of Mn to workers as well as overall increased Mn pollution affecting the general public. Here, we review exposure due to air pollution and inhalation in industrial settings; we also delve into the toxic effects of manganese on the brain such as oxidative stress, inflammatory response and transporter dysregulation. Additionally, we summarize current understandings underlying the mechanisms of Mn toxicity.

Combined platelet-rich plasma and cold water immersion treatment minimize the damage following a skeletal muscle stretch injury in rats.

The skeletal muscle stretch injuries are commonly observed in sports. In order to stimulate tissue healing, the platelet-rich plasma (PRP) and cold water immersion (CWI) are widely used in clinical practice. This study investigated the effects of isolated or combined PRP and/or CWI on the oxidative damage determined by a stretch injury induced in gastrocnemius muscle of rats. PRP and CWI are applied immediately after the injury, and the biochemical analysis was performed after 1, 3, 5, or 7 days. The levels of o thiobarbituric acid reactive substances and oxidized dichlorofluorescein were significantly increased, both in skeletal muscle tissue and erythrocytes preparations, and the combined PRP and CWI minimized these parameters. Moreover, combined PRP and CWI were more effective than the isolated treatments to increase catalase activity, also the ratio of reduced/oxidized glutathione, and the non-protein thiols (-SH) group levels. In conclusion, we could infer that the combination of these regular treatments used in an isolated form shows a great potential for treatments of muscular injuries.

Toxicological evaluation of naringin-loaded nanocapsules in vitro and in vivo.

Naringin is a flavonoid widely known for its pharmacological properties, such as: anti-inflammatory and antioxidant ones, being an ally to avoid oxidative damage. Although naringin is an active easily found in citrus fruits, it has low bioavailability, biodistribution and also undergoes biotransformation in naringenin, limiting the described effects. The use of nanocapsules as drug carriers may increase solubility, improve biodistribution, impede the biotransformation thereof, and thus could improve the performance of naringin for use in treating neurological diseases. Therefore, the objective of this work is to produce a nanocapsule containing naringin, validate an analytical method by RP-HPLC to determination of the drug in nanoparticle and evaluate the toxicity. To that end, the blank nanocapsules (NB, without the drug) or naringin-loaded nanocapsules (NN) at the concentration of 2 mg/mL were prepared by interfacial deposition of the preformed polymer and the quantification of naringin by HPLC. Toxicity of the formulations was evaluated in vitro in rat hippocampal slices and in vivo models with C. elegans and Danio rerio (zebrafish). The analytical parameters evaluated (linearity, limit of detection and quantification, specificity, precision, accuracy and robustness) indicated adequate method to assay of naringin in nanocapsules by HPLC. There was no indication of toxicity by the nanocapsules in the evaluated biological assays.

Sex-Specific Response of Caenorhabditis elegans to Methylmercury Toxicity.

Methylmercury (MeHg), an abundant environmental pollutant, has long been known to adversely affect neurodevelopment in both animals and humans. Several reports from epidemiological studies, as well as experimental data indicate sex-specific susceptibility to this neurotoxicant; however, the molecular bases of this process are still not clear. In the present study, we used Caenorhabditis elegans (C. elegans), to investigate sex differences in response to MeHg toxicity during development. Worms at different developmental stage (L1, L4, and adult) were treated with MeHg for 1 h. Lethality assays revealed that male worms exhibited significantly higher resistance to MeHg than hermaphrodites, when at L4 stage or adults. However, the number of worms with degenerated neurons was unaffected by MeHg, both in males and hermaphrodites. Lower susceptibility of males was not related to changes in mercury (Hg) accumulation, which was analogous for both wild-type (wt) and male-rich him-8 strain. Total glutathione (GSH) levels decreased upon MeHg in him-8, but not in wt. Moreover, the sex-dependent response of the cytoplasmic thioredoxin system was observed-males exhibited significantly higher expression of thioredoxin TRX-1, and thioredoxin reductase TRXR-1 expression was downregulated upon MeHg treatment only in hermaphrodites. These outcomes indicate that the redox status is an important contributor to sex-specific sensitivity to MeHg in C. elegans.

Molecular docking, and anti-biofilm activity of gold-complexed sulfonamides on Pseudomonas aeruginosa.

The antibacterial activity of sulfadiazine Au-PPh3, sulfadiazine Ph2P-Au-Au-PPh2, sulfamethoxazole Au-PPh3, sulfamethoxazole Ph2P-Au-Au-PPh2, sulfamethoxazole Au-PPh3 were tested against Pseudomonas aeruginosa. The antibacterial activity of sulfonamide was tested against P. aeruginosa through the MIC assay, quantitative analysis of biofilm inhibition and observation of biofilm formation with fluorescence microscopy. Besides, the compounds presented remarkable inhibition of P. aeruginosa biofilm formation. Furthermore, molecular docking was performed to identify the key structural features of these compounds with the binding site of the LasR receptor.

The antibacterial and anti-biofilm activity of gold-complexed sulfonamides against methicillin-resistant Staphylococcus aureus.

The drug-resistant strains of Staphylococcus aureus have been considered as one of the serious health threats, which are related to high patient hospitalization rates. Besides, Staphylococcus aureus biofilm formation exhibits a drug-tolerant nature and shows nonspecific resistance against a broad-spectrum of antibiotics. The emergence of drug-resistant bacteria stimulated the development of novel medicines as a strategy to control infections. In this study, we evaluated the antibacterial and anti-biofilm activity of gold-complexed sulfonamides against Staphylococcus aureus strains such as methicillin-resistant S. aureus and clinical isolates. Our data showed that the exposure of gold-complexed sulfonamides promoted a remarkable reduction in the bacterial adhesion. Also, confocal microscopy displayed the effects of the compounds on in the bacterial cell biofilm, revealed that the compounds decreased the biofilm formation. Our results also demonstrated that gold-complexed sulfonamides exhibited potent antibacterial activity against Staphylococcus aureus strains. Besides, all compounds presented a synergic antibacterial activity when were associated with classical antibiotics. Gold-complexed sulfonamide compounds did not promote toxic effects on Caenorhabditis elegans. Thus, our results showed that the coordination of sulfonamide with gold is a promising alternative in the development of safe and active compounds against methicillin-resistant and clinical isolates S. aureus.

Regulation of Mitochondrial Function and Glutamatergic System Are the Target of Guanosine Effect in Traumatic Brain Injury.

Traumatic brain injury (TBI) is a highly complex multi-factorial disorder. Experimental trauma involves primary and secondary injury cascades that underlie delayed neuronal dysfunction and death. Mitochondrial dysfunction and glutamatergic excitotoxicity are the hallmark mechanisms of damage. Accordingly, a successful pharmacological intervention requires a multi-faceted approach. Guanosine (GUO) is known for its neuromodulator effects in various models of brain pathology, specifically those that involve the glutamatergic system. The aim of the study was to investigate the GUO effects against mitochondrial damage in hippocampus and cortex of rats subjected to TBI, as well as the relationship of this effect with the glutamatergic system. Adult male Wistar rats were subjected to a unilateral moderate fluid percussion brain injury (FPI) and treated 15 min later with GUO (7.5 mg/kg) or vehicle (saline 0.9%). Analyses were performed in hippocampus and cortex 3 h post-trauma and revealed significant mitochondrial dysfunction, characterized by a disrupted membrane potential, unbalanced redox system, decreased mitochondrial viability, and complex I inhibition. Further, disruption of Ca2+ homeostasis and increased mitochondrial swelling was also noted. Our results showed that mitochondrial dysfunction contributed to decreased glutamate uptake and levels of glial glutamate transporters (glutamate transporter 1 and glutamate aspartate transporter), which leads to excitotoxicity. GUO treatment ameliorated mitochondrial damage and glutamatergic dyshomeostasis. Thus, GUO might provide a new efficacious strategy for the treatment acute physiological alterations secondary to TBI.

Lifespan Extension Induced by Caffeine in Caenorhabditis elegans is Partially Dependent on Adenosine Signaling.

Caffeine is a widely used psychoactive substance. Studies have shown that caffeine may play a protective role in aging-associated disorders. However, the mechanisms by which caffeine modulates aging are not yet clear. In this study, we have shown that caffeine increases Caenorhabditis elegans lifespan, delays its larval development, reduces reproduction and body length. These phenotypes were partly reversed by worm's exposure to adenosine, which suggest a putative common target. Moreover, they were dependent on a functional insulin/IGF-1-like pathway. Our results may shed light on new genetic determinants of aging.

POSITIVE EFFECTS OF RESISTANCE TRAINING ON INFLAMMATORY PARAMETERS IN MEN WITH METABOLIC SYNDROME RISK FACTORS.

BACKGROUND: evidences have shown a strongly association between metabolic syndrome (MS), cardiovascular diseases and chronic low-grade inflammation, being this last, related with the occurrence of sarcopenia and atherosclerosis. Despite several benefits, the effects of resistance training (RT) on inflammatory profile are controversial. Thereby, this study aims to investigate the effects of a RT on the inflammatory profile of men with MS risk factors. METHODS: fifteen sedentary men (57.53 ± 7.07 years old) with 2 or more MS components underwent a RT for 14 weeks (3 times per week), with intensity ranging between 40 and 70% of one repetition maximum. The dual-energy X-ray absorptiometry was used to body composition assessment and serum was collected to evaluate biochemical and inflammatory parameters before and after the RT. RESULTS: despite the absence of changes in body weight, total muscular content and biochemical parameters, the individuals demonstrated a reduction on body fat content (p < 0.05). Furthermore, the RT resulted in lower circulating levels of tumor necrosis factor alpha and interleukin- 6 (p < 0.05), in higher levels of intelerukin-10 (p < 0.05) and in the stabilization of interleukin-1 beta and interferon-gamma concentrations. It was concluded that a moderate RT benefits inflammatory profile, contributing to a lower risk of cardiovascular diseases.

Introducción: la evidencia muestra la relación entre síndrome metabólico (SM), enfermedades cardiovasculares e inflamación crónica de bajo grado, que está relacionada con la aparición de sarcopenia y aterosclerosis. A pesar de muchos beneficios, los efectos del entrenamiento de resistencia (ER) sobre la inflamación son controvertidos. Este estudio tiene como objetivo investigar los efectos de 14 semanas de ER en el perfil inflamatorio de hombres con factores de riesgo para SM. Métodos: quince varones sedentarios (57,53 ± 7,07 años) con 2 o más componentes del SM fueron sometidos a un ER moderado durante 14 semanas (tres veces a la semana), con una intensidad que oscila entre 40 y 70% de una repetición máxima. La absorciometría dual de rayos X se utilizó para la evaluación de la composición corporal y el suero se recogió para evaluar los parámetros bioquímicos e inflamatorios antes y después de la ER. Resultados: a pesar del mantenimiento de la masa corporal, la masa muscular total y los parámetros bioquímicos, hubo una reducción en la grasa corporal (p < 0,05). Además, el ER disminuyó los niveles de factor de necrosis tumoral alfa e interleucina-6 circulante (p < 0,05), aumentó la concentración de interleucina-10 (p < 0,05) y mantuvo la interleucina-1 y el interferón-gamma. Se concluyó que 14 semanas de ER moderado provocan beneficios sobre el perfil inflamatorio, contribuyendo a la reducción del riesgo cardiovascular.

Diphenyl diselenide modulates gene expression of antioxidant enzymes in the cerebral cortex, hippocampus and striatum of female hypothyroid rats.

INTRODUCTION: Cellular antioxidant signaling can be altered either by thyroid disturbances or by selenium status. AIMS: To investigate whether or not dietary diphenyl diselenide can modify the expression of genes of antioxidant enzymes and endpoint markers of oxidative stress under hypothyroid conditions. METHODS: Female rats were rendered hypothyroid by continuous exposure to methimazole (MTZ; 20 mg/100 ml in the drinking water) for 3 months. Concomitantly, MTZ-treated rats were either fed or not with a diet containing diphenyl diselenide (5 ppm). mRNA levels of antioxidant enzymes and antioxidant/oxidant status were determined in the cerebral cortex, hippocampus and striatum. RESULTS: Hypothyroidism caused a marked upregulation in mRNA expression of catalase, superoxide dismutase (SOD-1, SOD-3), glutathione peroxidase (GPx-1, GPx-4) and thioredoxin reductase (TrxR-1) in brain structures. SOD-2 was increased in the cortex and striatum, while TrxR-2 increased in the cerebral cortex. The increase in mRNA expression of antioxidant enzymes was positively correlated with the Nrf-2 transcription in the cortex and hippocampus. Hypothyroidism caused oxidative stress, namely an increase in lipid peroxidation and reactive oxygen species levels in the hippocampus and striatum, and a decrease in nonprotein thiols in the cerebral cortex. Diphenyl diselenide was effective in reducing brain oxidative stress and normalizing most of the changes observed in gene expression of antioxidant enzymes. CONCLUSION: The present work corroborates and extends that hypothyroidism disrupts antioxidant enzyme gene expression and causes oxidative stress in the brain. Furthermore, diphenyl diselenide may be considered a promising molecule to counteract these effects in a hypothyroidism state.

δ-Aminolevulinate dehydratase activity in lung cancer patients and its relationship with oxidative stress.

This study investigated the δ-aminolevulinate dehydratase (δ-ALA-D) activity in whole blood as well as the parameters of oxidative stress, such as reactive species (RS) levels in serum, thiobarbituric acid reactive substances (TBARS) levels, the superoxide dismutase (SOD) and catalase (CAT) activities, as well as total thiols (T-SH) and non-protein thiols (NPSH) levels in platelets. Moreover, the content of vitamin C and E in plasma and serum, respectively, in lung cancer patients was also investigated. We collected blood samples from patients (n=28) previously treated for lung cancer with chemotherapy. Patients were classified as stage IIIb and IV according to the Union for International Cancer Control (UICC). Results showed a decrease of 37% in δ-ALA-D activity in patients with lung cancer when compared to the control group. RS and TBARS levels were 8% and 99% higher in the patient group, respectively. The activity of SOD and CAT as well as the vitamin C content were 41%, 35% and 127% lower in patients when compared with controls, respectively. However, T-SH and vitamin E levels were 27% and 44% higher in lung cancer patients, respectively. Results show that the overproduction of reactive species in patients with lung cancer may be interfering with the activity of δ-ALA-D. Likewise, the decrease in the activity of this enzyme may be contributing for the oxidative stress.

Co-exposure of the organic nanomaterial fullerene C60 with benzo[a]pyrene in Danio rerio (zebrafish) hepatocytes: evidence of toxicological interactions.

Compounds from the nanotechnology industry, such as carbon-based nanomaterials, are strong candidates to contaminate aquatic environments because their production and disposal have exponentially grown in a few years. Previous evidence shows that fullerene C60, a carbon nanomaterial, can facilitate the intake of metals or PAHs both in vivo and in vitro, potentially amplifying the deleterious effects of these toxicants in organisms. The present work aimed to investigate the effects of fullerene C60 in a Danio rerio (zebrafish) hepatocyte cell lineage exposed to benzo[a]pyrene (BaP) in terms of cell viability, oxidative stress parameters and BaP intracellular accumulation. Additionally, a computational docking was performed to investigate the interaction of the fullerene C60 molecule with the detoxificatory and antioxidant enzyme πGST. Fullerene C60 provoked a significant (p<0.05) loss in cellular viability when co-exposed with BaP at 0.01, 0.1 and 1.0 µg/L, and induced an increase (p<0.05) in BaP accumulation in the cells after 3 and 4h of exposure. The levels of reactive oxygen species (ROS) in the cells exposed to BaP were diminished (p<0.05) by the fullerene addition, and the increase of the GST activity observed in the BaP-only treated cells was reduced to the basal levels by co-exposure to fullerene. However, despite the potential of the fullerene molecule to inhibit π GST activity, demonstrated by the computational docking, the nanomaterial did not significantly (p>0.05) alter the enzyme activity when added to GST purified extracts from the zebrafish hepatocyte cells. These results show that fullerene C60 can increase the intake of BaP into the cells, decreasing cell viability and impairing the detoxificatory response by phase II enzymes, such as GST, and this latter effect should be occurring at the transcriptional level.

Protective action of ethanolic extract of Rosmarinus officinalis L. in gastric ulcer prevention induced by ethanol in rats.

The pathology of a gastric ulcer is complex and multifactorial. Gastric ulcers affect many people around the world and its development is a result of the imbalance between aggressive and protective factors in the gastric mucosa. In this study, we evaluated the ethanolic extract of Rosmarinus officinalis L. (eeRo); this plant, more commonly known as rosemary, has attracted the interest of the scientific community due to its numerous pharmacological properties and their potential therapeutic applications. Here, we tested the preventive effects of eeRo against gastric ulcer induced by 70% ethanol in male Wistar rats. In addition, we aimed to clarify the mechanism involved in the preventive action of the eeRo in gastric ulcers. Based on the analysis of markers of oxidative damage and enzymatic antioxidant defense systems, the measurement of nitrite and nitrate levels and the assessment of the inflammatory response, the eeRo exhibited significant antioxidant, vasodilator and antiinflammatory properties.

Organic and inorganic forms of selenium inhibited differently fish (Rhamdia quelen) and rat (Rattus norvergicus albinus) delta-aminolevulinate dehydratase.

Selenium contamination in the aquatic environment can produce severe toxic effects to fish. The mammalian sulfhydryl-containing enzyme, delta-aminolevulinate dehydratase (delta-ALA-D), is inhibited after exposure to organic and inorganic forms of selenium. In the present study, the inhibitory effect of (PhSe)2, (BuSe)2, and Na2SeO3 on the activity of fish hepatic and gill delta-ALA-D was investigated and compared with the rat liver enzyme. Results indicated that delta-ALA-D activity varied considerably depending on the tissue, selenium form, and species considered. For fish (liver and gill), the IC50 values for delta-ALA-D inhibition by (PhSe)2, (BuSe)2, and Na2SeO3 were 274 and 76, 985 and 693, and 386 and 902 microM, respectively. For rat liver these values were 7, 10, and 5 microM, respectively. In contrast, fish and rat subcellular fractions similarly increased the oxidative effect of (PhSe)2 toward sulfhydryl groups from DTT. These catalytic properties of subcellular fractions from fish and rat liver were abolished by heat treatment. Taking into account that aquatic organisms can be in contact with higher concentrations of selenium for longer periods of time and accumulate more selenium than terrestrial animals, it is reasonable to suppose that fish delta-ALA-D can be a potential target for organic and inorganic selenium forms present in aquatic contaminated environments. From an ecotoxicological point of view, our results suggest a link between selenium-induced anemia signs in fish and the sensitivity of fish delta-ALA-D to selenium in natural habitats.

Extracellular conversion of guanine-based purines to guanosine specifically enhances astrocyte glutamate uptake.

Guanosine (GUO) has been shown to stimulate glutamate uptake in primary astrocyte cultures. The purpose of this study was to determine the effect and specificity of guanine- or adenine-based purines on glutamate and GABA uptake in cultured astrocytes. Stimulatory effect on glutamate uptake was observed with GUO, GMP or GTP. Simultaneous exposure with these guanine-based purines did not show an additive effect. We also investigated a possible interconversion of guanine-based purines during incubation time. Action by GTP was excluded since the hydrolysis resistant GTP analog, GMP-PNP did not stimulate glutamate uptake. Addition of an ecto-5'-nucleotidase inhibitor abolished GMP-stimulatory effect on glutamate uptake, without affecting GUO action. Taken together, these results suggest that GUO is the guanine-based purines responsible for glutamate uptake activation. In addition, the stimulatory effect on glutamate uptake was not observed with adenine-based purines. Moreover, GABA uptake was not activated by GUO. These results point to specificity in the interaction between GUO and the astrocyte glutamate uptake system.