Investigation of the cytotoxicity, genotoxicity and antioxidant prospects of JM-20 on human blood cells: A multi-target compound with potential therapeutic applications.

JM-20 is a 1,5-benzodiazepine compound fused to a dihydropyridine fraction with different pharmacological properties. However, its potential toxic effects on blood cells have not yet been reported. Thus, the present study aimed to investigate, for the first time, the possible cytotoxicity of JM-20 through cell viability, cell cycle, morphology changes, reactive species (RS) to DCFH-DA, and lipid peroxidation in human leukocytes, its hemolytic effect on human erythrocytes, and its potential DNA genotoxicity using plasmid DNA in vitro. Furthermore, the compound's ability to reduce the DPPH radical was also measured. Human blood was obtained from healthy volunteers (30 ± 10 years old), and the leukocytes or erythrocytes were immediately isolated and treated with different concentrations of JM-20. A cytoprotective effect was exhibited by 10 µM JM-20 against 1 mM tert-butyl hydroperoxide (t-but-OOH) in the leukocytes. However, the highest tested concentrations of the compound (20 and 50 µM) changed the morphology and caused a significant decrease in the cell viability of leukocytes (p < 0.05, in comparison with Control). All tested concentrations of JM-20 also resulted in a significant increase in intracellular RS as measured by DCFH-DA in these cells (p < 0.05, in comparison with Control). On the other hand, the results point out a potent antioxidant effect of JM-20, which was similar to the classical antioxidant α-tocopherol. The IC50 value of JM-20 against the lipid peroxidation induced by (FeII) was 1.051 µM ± 0.21, while the IC50 value of α-tocopherol in this parameter was 1.065 µM ± 0.34. Additionally, 50 and 100 µM JM-20 reduced the DPPH radical in a statistically similar way to the 100 µM α-tocopherol (p < 0.05, in comparison with the control). No significant hemolysis in erythrocytes, no cell cycle changes in leukocytes, and no genotoxic effects in plasmid DNA were induced by JM-20 at any tested concentration. The in silico pharmacokinetic and toxicological properties of JM-20, derivatives, and nifedipine were also studied. Here, our findings demonstrate that JM-20 and its putative metabolites exhibit similar characteristics to nifedipine, and the in vitro and in silico data support the low toxicity of JM-20 to mammals.

Should ebselen be considered for the treatment of mercury intoxication? A minireview.

Mercury is a ubiquitous environmental contaminant and can be found in inorganic (Hg0, Hg+ and Hg2+) and organic forms (chiefly CH3Hg+ or MeHg+). The main route of human, mammals and bird exposure occurs via predatory fish ingestion. Occupational exposure to Hg0 (and Hg2+) can also occur; furthermore, in gold mining areas the exposure to inorganic Hg can also be high. The toxicity of electrophilic forms of Hg (E+Hg) is mediated by disruption of thiol (-SH)- or selenol (-SeH)-containing proteins. The therapeutic approaches to treat methylmercury (MeHg+), Hg0 and Hg2+ are limited. Here we discuss the potential use of ebselen as a potential therapeutic agent to lower the body burden of Hg in man. Ebselen is a safe drug for humans and has been tested in clinical trials (for instance, brain ischemia, noise-induce hearing loss, diabetes complications, bipolar disorders) at doses varying from 400 to 3600 mg per day. Two clinical trials with ebselen in moderate and severe COVID are also approved. Ebselen can be metabolized to an intermediate with -SeH (selenol) functional group, which has a greater affinity to electrophilic Hg (E+Hg) forms than the available thiol-containing therapeutic agents. Accordingly, as observed in vitro and rodent models in vivo, Ebselen exhibited protective effects against MeHg+, indicating its potential as a therapeutic agent to treat MeHg+ overexposure. The combined use of ebselen with thiol-containing molecules (e.g. N-acetylcysteine and enaramide)) is also commented, because they can have synergistic protective effects against MeHg+.

Night fasting as an alternative to improve nutritional support and glycaemic control in hospitalised patients with exclusive enteral nutrition.

BACKGROUND: Enteral nutrition (EN) assists in the nutritional status of hospitalised patients unable to feed orally. The aim of this study was to determine which method-continuous EN or discontinuous EN, a diet in which the infusion is discontinued for 4h during the night,-is more effective in meeting nutrient recommendations and improving glycaemic control and biochemical parameters related to protein anabolism. METHODS: Patients were divided into two groups: discontinuous (EN administered in mL/h, 18h/day, 4-h night fasting) and continuous (EN administered in mL/h, 22h/day). All patients with EN receive the diet over a 22-h daily period, in which the diet is suspended for two hours/day for daily hospital routines such as bathing, and physiotherapy, and followed for seven days. Evaluated data: prescribed and administered volume, calories, protein, and fibre; capillary blood glucose; erythrogram; serum albumin. RESULTS: 52 patients were followed-up, with 23 (44.2%) in the discontinuous group and 29 (55.8%) in the continuous group. Compared with the continuous group, the discontinuous group received volumes closer to those prescribed, equal or higher calories, and more protein. The capillary glucose values were within the reference range in the discontinuous group, while the continuous group presented elevated values. Both groups presented hypoalbuminaemia, haemoglobin, and haematocrit below the reference values; however, in the discontinuous group, the serum albumin values improved during hospitalisation relative to the continuous. CONCLUSIONS: The method involving discontinuation of EN for 4h was more effective in meeting nutrient recommendations compared with the continuous method. Additionally, in the discontinuous group, we observed a better control of glycaemia when compared to that of the continuous group.

Effect of Prepartum Maternal Supplementation with Diphenyl Diselenide on Biochemical, Immunological, and Oxidative Parameters of the Offspring.

This study aimed to assess the impact of prepartum maternal diphenyl diselenide (PhSe)2 supplementation on the development, biochemical, immune, and antioxidant parameters of calves. Eighteen Holstein breed calves were used, born to females who were or were not subjected to supplementation, at 42, 28, and 14 days prior to calving. The (PhSe)2 group (DDG) was administered 3 µmol/kg of (PhSe)2 in 4 mL of dimethyl sulfoxide (DMSO), while the DMSO and NaCl groups were administered 4 mL of DMSO and 0.9% NaCl, subcutaneously. The calves were evaluated based on their weight, withers height, body condition score 24 h post-birth (0), as well on days 14, 28, 42, 56, 70. Blood samples were also taken to determine serum variables. Calves on the DDG showed higher average levels of total protein, albumin, and globulins on day 0, and the immunoglobulin G level was significantly higher than the other groups on days 0, 14, 56, 70. Maternal supplementation showed immunomodulatory effect on calves, evidenced by the exceptional rates of passive immunity transfer, as well as the enhancement of humoral immunity. Our research offers fresh insights into the immunomodulatory potential of (PhSe)2, making it a viable alternative in facing this challenging phase, rearing dairy calves.

The Drosophila melanogaster ACE2 ortholog genes are differently expressed in obesity/diabetes and aging models: Implications for COVID-19 pathology.

The Spike glycoprotein of SARS-CoV-2, the virus responsible for coronavirus disease 2019, binds to its ACE2 receptor for internalization in the host cells. Elderly individuals or those with subjacent disorders, such as obesity and diabetes, are more susceptible to COVID-19 severity. Additionally, several SARS-CoV-2 variants appear to enhance the Spike-ACE2 interaction, which increases transmissibility and death. Considering that the fruit fly is a robust animal model in metabolic research and has two ACE2 orthologs, Ance and Acer, in this work, we studied the effects of two hypercaloric diets (HFD and HSD) and aging on ACE2 orthologs mRNA expression levels in Drosophila melanogaster. To complement our work, we analyzed the predicted binding affinity between the Spike protein with Ance and Acer. We show for the first time that Ance and Acer genes are differentially regulated and dependent on diet and age in adult flies. At the molecular level, Ance and Acer proteins exhibit the potential to bind to the Spike protein in different regions, as shown by a molecular docking approach. Acer, in particular, interacts with the Spike protein in the same region as in humans. Overall, we suggest that the D. melanogaster is a promising animal model for translational studies on COVID-19 associated risk factors and ACE2.

The Insecticidal Activity of Rhinella schneideri (Werner, 1894) Paratoid Secretion in Nauphoeta cinerea Cocroaches.

Rhinella schneideri is a common toad found in South America, whose paratoid toxic secretion has never been explored as an insecticide. In order to evaluate its insecticidal potential, Nauphoeta cinerea cockroaches were used as an experimental model in biochemical, physiological and behavioral procedures. Lethality assays with Rhinella schneideri paratoid secretion (RSPS) determined the LD50 value after 24 h (58.07µg/g) and 48 h exposure (44.07 µg/g) (R2 = 0.882 and 0.954, respectively). Acetylcholinesterase activity (AChE) after RSPS at its highest dose promoted an enzyme inhibition of 40%, a similar effect observed with neostigmine administration (p < 0.001, n= 5). Insect locomotion recordings revealed that RSPS decreased the distance traveled by up to 37% with a concomitant 85% increase in immobile episodes (p < 0.001, n = 36). RSPS added to in vivo cockroach semi-isolated heart preparation promoted an irreversible and dose dependent decrease in heart rate, showing a complete failure after 30 min recording (p < 0.001, n ≥ 6). In addition, RSPS into nerve-muscle preparations induced a dose-dependent neuromuscular blockade, reaching a total blockage at 70 min at the highest dose applied (p < 0.001, n ≥ 6). The effect of RSPS on spontaneous sensorial action potentials was characterized by an increase in the number of spikes 61% (p < 0.01). Meanwhile, there was 42% decrease in the mean area of those potentials (p < 0.05, n ≥ 6). The results obtained here highlight the potential insecticidal relevance of RSPS and its potential biotechnological application.

Molecular docking and in vitro evaluation of a new hybrid molecule (JM-20) on cholinesterase activity from different sources.

The main function of AChE is the hydrolysis of the neurotransmitter acetylcholine (ACh) at the neuromuscular and in cholinergic brain synapses. In some pathologies, loss of cholinergic neurons may be associated with a deficiency of ACh in specific brain areas. Consequently, the study of new safe drugs that inhibit AChE is important, because they can increase ACh levels in the synaptic cleft without adverse effects. Here, we evaluated the effects of JM-20 (a benzodiazepine-dihydropyridine hybrid molecule) on cholinesterase (ChE) activities from distinct sources (AChE from Electrophorus electricus (EeAChE), human erythrocyte membranes (HsAChE (ghost)), total erythrocyte (HsAChE (erythrocyte)) and BChE from plasma (HsBChE) and purified enzyme from the horse (EcBChE)). Kinetic parameters were determined in the presence of 0.05-1.6 mM of substrate concentration. The interactions ChEs with JM-20 were performed using molecular docking simulations. JM-20 inhibited all tested AChE but not BChE. The IC50 values were 123 nM ± 0.2 (EeAChE), 158 nM ± 0.1 (ghost HsAChE), and 172 nM ± 0.2 (erythrocytic HsAChE). JM-20 caused a mixed type of inhibition (it altered Km and Vmax of AChE). The molecular docking indicated the binding poses and the most plausible active isomer of JM-20. Besides giving important data for future drug design, our results help us understand the mode of action of JM-20 as a specific inhibitor of AChE enzymes.

Biochemical and nutritional profile of patients with exclusive enteral nutrition during hospitalization / Perfil bioquímico y nutricional de pacientes con nutrición enteral exclusiva durante hospitalización

BACKGROUND: Enteral nutrition therapy (ENT) is intended to restore the nutritional status of patients. OBJECTIVE: The objective of this study was to evaluate the biochemical and nutritional profile of hospitalized patients with exclusive enteral nutrition. METHODS: It is a longitudinal study, with a sample of 42 hospitalized young and elder adults, with exclusive ENT, for at least seven days. The patients were submitted to nutritional, anthropometric (Body Mass Index, corrected arm muscle area and arm muscle circumference) and biochemical evaluation as albumin, hemoglobin, C-reactive protein, vitamin C, Iron, Zinc and Copper serum. Results and DISCUSSION: It was observed that anthropometric parameters such as weight, BMI, muscle area and circumference increased during hospitalization time only in the elderly (P= 0.016; P=0.018; P = 0.021; P = 0.020). The percentage of adequacy in energy, protein and micronutrients with vitamin C, iron, zinc and copper were adequate during hospitalization for both age groups, according to the estimated average needs. Serum levels of these micronutrients were within normal values for both age groups, with the exception of zinc, which decreased during hospitalization in the elderly. This may be associated with the greater need for this mineral in this age group or with a implicate in its absorption. CONCLUSION: The ENT influence the weight and muscle mass gain in hospitalized elderly patients and, although the appropriate administration of micronutrients, the absorption of zinc was affected. Therefore, monitoring of enteral nutrition is essential in order to avoid worsening nutritional status during hospitalization

INTRODUCCIÓN: La terapia de nutrición enteral (TNE) tiene la finalidad de recuperar el estado nutricional de los pacientes. Objectivo: Se evaluó el perfil bioquímico y nutricional de pacientes hospitalizados con nutrición enteral exclusiva. MÉTODOS: Estudio longitudinal, con muestra compuesta por 42 adultos y ancianos hospitalizados, con TNE exclusiva, por lo menos siete días. Los pacientes fueron sometidos a evaluación nutricional, antropométrica (Índice de Masa Corporal, área muscular del brazo corregida y circunferencia del brazo) y bioquímica como albúmina, proteína C-reactiva, vitamina C, hierro zinc y cobre sérico. Resultados y DISCUSIÓN: Se observó que los parámetros antropométricos como el peso, IMC, área y circunferencia muscular del brazo aumentaron durante el tiempo de internación solo en los ancianos (P= 0.016; P=0.018; P = 0.021; P = 0.020). El porcentaje de adecuación de energía, proteica y micronutrientes como vitamina C, hierro, zinc y cobre fueron adecuados durante el tiempo de internación para ambos grupos de edad, de acuerdo con las necesidades medias estimadas. Los niveles séricos de estos micronutrientes se mantuvieron dentro de los valores normales para ambos grupos de edad, a excepción del zinc, que disminuyó durante la hospitalización en ancianos. Esto puede asociarse a la mayor necesidad de este mineral en este grupo de edad o a un deterioro en su absorción. CONCLUSIÓN: La TNE influye en el aumento de peso y la masa muscular en ancianos y, apesar de la administración adecuada de micronutrientes, se observó un deterioro en la absorción de zinc. Por lo tanto, el monitoreo de la nutrición enteral es esencial para evitar el empeoramiento del estado nutricional durante la hospitalización

High-sucrose diet induces diabetic-like phenotypes and oxidative stress in Drosophila melanogaster: Protective role of Syzygium cumini and Bauhinia forficata.

Diet is a key component for development and longevity of organisms. Here, the fruit fly was used to evaluate the detrimental effects caused by consumption of high-sucrose diets (HSD), namely phenotypic responses linked to insulin signaling and oxidative stress. The protective effects of extracts from medicinal plants Syzygium cumini and Bauhinia forficata were investigated. HSD intake (15% and 30%) delayed the time to pupation and reduced the number of white pupae. In adult flies, the intake of diets was associated with mortality and increased levels of glucose+trehalose, triacylglycerols and hydrogen peroxide. Indeed, 30% HSD induced body-weight loss, mitochondrial dysfunction and changes in acetylcholinesterase, δ-aminolevulinate dehydratase and antioxidant enzymes activity. Catalase, superoxide dismutase, keap1, HSP70, dILP-5 and Insulin receptor mRNA levels were over-expressed in flies emerged from 30% HSD. The extract treatments blunted the developmental alterations elicited by diets. Syzygium cumini extract was more efficient than B. forficata in reducing hyperglycaemia, redox disturbances and the changes in mRNA expression of insulin receptor.

Diphenyl diselenide attenuates oxidative stress and inflammatory parameters in ulcerative colitis: A comparison with ebselen.

OBJETIVE: The aim of this study was to evaluate the effects of diphenyl diselenide (PhSe)2 and ebselen (EB) in ulcerative colitis (UC) induced by dextran sulfate sodium (DSS) in rats. METHODS: The effects of (PhSe)2 and EB in rats submitted to DSS-induced colitis were determined by measurement of oxidative stress parameters, inflammatory response and bowel histopathological alterations. RESULTS: Animals developed moderate to severe neutrophil infiltration in histopathology assay in DSS rats and (PhSe)2 improved this response. Moreover, the treatment with (PhSe)2 decreased the oxidative damage in lipids and proteins, as well as reversed the superoxide dismutase (SOD) and catalase (CAT) levels in rats treated with DSS. EB was able only to reverse damage in lipids and the low levels of SOD in this animal model. CONCLUSIONS: The organoselenium compounds tested demonstrated an anti-inflammatory and antioxidant activity reducing the colon damage, being (PhSe)2 more effective than EB.

Effect of antioxidant potential on severity of cirrhosis in humans / Efecto del potencial antioxidante para las complicaciones de la cirrosis en los seres humanos

Background/Aims: to examine the relationship between the antioxidant potential and severity parameters of cirrhosis in humans. Methods: fifteen patients with hepatic cirrhosis (nine subjects - Child group B, and six subjects - Child group C) and nine control subjects were enrolled in the study. The main criteria taken into account to characterize the diagnosis of cirrhosis and its complications were the AST: ALT ratio, AST to platelet ratio index, Bonacini score, Meld score and Child classification. Those parameters were determined based on laboratory results and patient’s clinical records. Se, Zn, ascorbic acid (AA) levels and oxidative stress parameters were measured in blood samples of cirrhotic patients. Results: the analysis of plasma levels of Se and AA showed low concentrations in cirrhotic patients compared with control subjects (P < 0.05). Though, there was a positive correlation between plasma of Se and severity parameters of cirrhosis in patients of Child group B and C. In the activity of the antioxidant enzymes only catalase was lower in patients of Child group C compared with control group. Conclusion: we found low plasma levels of Se and AA among cirrhotic patients. However, is not clear why selenium levels tend to increase with the severity of liver cirrhosis (AU)

Introducción/Objetivos: examinar la relación entre los potenciales antioxidantes y los parámetros de gravedad de la cirrosis en los seres humanos. Métodos: quince pacientes con cirrosis hepática (nueve sujetos - grupo Child B, y seis sujetos - grupo Child C) y nueve sujetos control fueron incluidos en el estudio. Los principales criterios que se tuvieron en cuenta para caracterizar el diagnóstico de la cirrosis y sus complicaciones fueron la AST: relación de ALT, AST índice de la relación de plaquetas, clasificación Bonacini, clasificación MELD y clasificación de Child. Estos parámetros fueron determinados con base en los resultados de laboratorio y los registros clínicos del paciente. Se midieron los niveles de Zn, ácido ascórbico (AA) y los parámetros de estrés oxidativo en muestras de sangre de pacientes cirróticos. Resultados: el análisis de los niveles plasmáticos de Se y AA mostraron bajas concentraciones en los pacientes cirróticos en comparación con los sujetos control (P < 0,05); sin embargo, hubo una correlación positiva entre el plasma de Se y los parámetros de gravedad de la cirrosis en pacientes del grupo Child B y C. En la actividad de las enzimas antioxidantes catalasa solamente fue menor en los pacientes del grupo Child C, en comparación con el grupo control. Conclusión: se encontraron niveles bajos en plasma de Se y AA en pacientes cirróticos. Sin embargo, no está claro por qué los niveles de selenio tienden a aumentar con la gravedad de la cirrosis hepática (AU)

Modulatory effect of diphenyl diselenide in Carioca High- and Low-conditioned Freezing rats.

Diphenyl diselenide ([PhSe]2)is an organoselenium compound that has interesting pharmacological properties, including antioxidant, glutathione peroxidase-mimetic, and neuroprotective effects. The objective of the present study was to investigate the possible modulatory effect of (PhSe)2 in 17th-generation Carioca high-and low-conditioned freezing (CHF and CLF) rats, an animal model of generalized anxiety disorders. (PhSe)2 was administered at three doses (10, 50, and 100mg/kg) in CHF and CLF rats, and their anxiety-like profiles (conditioned freezing patterns) were measured before and 30min after treatment. A significant difference was found in freezing scores between CHF and CLF animals before treatment (t70=12.50, p<0.001). Treatment with (PhSe)2 at 10 and 50mg/kg decreased freezing in CHF rats but significantly increased freezing at 100mg/kg. (PhSe)2 increased freezing in CLF animals at 50 and 100mg/kg (p<0.01). These results indicate that (PhSe)2 exerts both anxiolytic- and anxiogenic-like effects in bi-directional rat lines. Distinct genetic profiles of the CHF and CLF lines may influence biochemical functions and lead to differential responses to aversive situations and various drugs like (PhSe)2.

Antioxidant properties of Taraxacum officinale fruit extract are involved in the protective effect against cellular death induced by sodium nitroprusside in brain of rats.

CONTEXT: Taraxacum officinale Weber (Asteraceae), known as dandelion, is used for medicinal purposes due to its choleretic, diuretic, antitumor, antioxidant, antiinflammatory, and hepatoprotective properties. OBJECTIVE: We sought to investigate the protective activity of T. officinale fruit extract against sodium nitroprusside (SNP)-induced decreased cellular viability and increased lipid peroxidation in the cortex, hippocampus, and striatum of rats in vitro. To explain the mechanism of the extract's antioxidant activity, its putative scavenger activities against NO, DPPH·, OH·, and H(2)O(2) were determined. METHODS: Slices of cortex, hippocampus, and striatum were treated with 50 µM SNP and T. officinale fruit ethanolic extract (1-20 µg/mL) to determine cellular viability by MTT reduction assay. Lipid peroxidation was measure in cortical, hippocampal and striatal slices incubates with SNP (5 µM) and T. officinale fruit extract (1-20 µg/mL). We also determined the scavenger activities of T. officinale fruit extract against NO·, DPPH·, OH·, and H(2)O(2), as well as its iron chelating capacity. RESULTS: The extract (1, 5, 10, and 20 µg/mL) protected against SNP-induced decreases in cellular viability and increases in lipid peroxidation in the cortex, hippocampus, and striatum of rats. The extract had scavenger activity against DPPH· and NO· at low concentrations and was able to protect against H(2)O(2) and Fe(2+)-induced deoxyribose oxidation. CONCLUSION: T. officinale fruit extract has antioxidant activity and protects brain slices against SNP-induced cellular death. Possible mechanisms of action include its scavenger activities against reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are attributed to the presence of phenolic compounds in the extract.

In vivo and in vitro genotoxicity studies of aqueous extract of Xanthium spinosum

The use of plants as a source of palliative or cure for pathological conditions is quite common worldwide. Xanthium spinosum (Asteraceae), popularly known in Brazil as 'espinho de carneiro', is an annual weed from South America, which has been used by empiric medicine to treat neoplasias. Owing to the extensive use of the above-mentioned plant and to the lack of reports about the real effects of its infusion, current study evaluated the genotoxic potential of its aqueous extract at concentrations 0.02 g L-1, 0.1 g L-1 and 0.2 g L-1 by fish micronucleus test and by comet human leukocytes assay. The micronucleus test featured at least 50 cells with micronuclei to every 2,000 cells scored, as a mutagenic parameter. The comet assay was used as a parameter for assessing the level of cell damage and the damage index. Since no significant changes in strain cells exposed to the aqueous extract in the comet and micronucleus assays were reported, it seems that no genotoxicity evidence is extant at the concentrations and in the assays performed.

Em diversos lugares do mundo a utilização de plantas como fonte paliativa ou de cura para determinadas condições patológicas é bastante comum. No Brasil, essa prática não se torna diferente devido à ampla biodiversidade da fauna e flora presentes no País. Nesse contexto, surge a Xanthium spinosum (Asteraceae), conhecida popularmente como "espinho-de-carneiro", um arbusto anual introduzido na América do Sul, o qual tem sido utilizado empiricamente no tratamento de neoplasias. Sabendo do extensivo uso dessa planta em contrapartida com nenhum estudo reportando os reais efeitos de sua infusão, o objetivo do estudo foi avaliar a genotoxicidade do extrato aquoso nas concentrações de 0,02 g L-1, 0,1 g L-1 e 0,2 g L-1, através do ensaio do micronúcleo písceo e do ensaio cometa em leucócitos de sangue humano. O ensaio do micronúcleo tem como parâmetro mutagênico a presença de no mínimo 50 células com micronúcleo em uma contagem de 2.000 células por amostra, enquanto o ensaio cometa utiliza como parâmetro o nível de dano e o índice de dano. Os resultados mostram que não foi possível observar mudanças significativas nas células expostas ao extrato aquoso, em ambos os testes, o que sugere não existir evidência de genotoxicidade nas concentrações utilizadas no ensaio.

Effect of repeated restraint stress and clomipramine on Na+/K+-ATPase activity and behavior in rats.

Activation of the limbic-hypothalamic-pituitary-adrenal axis (LHPA) and the release of glucocorticoids are fundamental for the adaptive response and immediate survival of an organism in reaction to acute stimuli. However, high levels of glucocorticoids in the brain may produce neuronal injury and a decrease of Na(+)/K(+)-ATPase activity, with effects on neurotransmitter signaling, neural activity, as well as the whole animal behavior. Clomipramine is a tricyclic antidepressant that inhibits the reuptake of serotonin and norepinephrine by indirect actions on the dopaminergic system and LHPA axis. Its chronic use increases the body's ability to cope with stress; however, high doses can potentiate its side effects on memory, learning, and sensory motor function. The purpose of the present study was to compare the effect of repeated restraint stress and clomipramine treatment on Na(+)/K(+)-ATPase activity and on the behavior of male rats. Changes in the behavioral response were evaluated by measuring the memory, learning, anxiety, and exploratory responses. Our results showed that exposure to repeated restraint stress reduced levels of Na(+)/K(+)-ATPase in brain structures and changed short and long-term memory, learning, and exploratory response when compared to the control group. Exposure to clomipramine treatment increased anxiety levels and reduced Na(+)/K(+)-ATPase activity in the cerebral cortex as well as short term memory, learning, and exploratory response. In conclusion, the present results provide additional evidence concerning how repeated restraint stress and clomipramine chronically administered at higher dose levels affect the neural activity and behavior of male rats.

Effects of in vivo treatment with diphenyl ditelluride on the phosphorylation of cytoskeletal proteins in cerebral cortex and hippocampus of rats.

In this work, we investigated the effect of a single subcutaneous injection of diphenyl ditelluride (PheTe)(2) in 15-day-old Wistar rats (0.3 micromol/kg body weight) on the phosphorylation of intermediate filament (IF) proteins in cerebral cortex and hippocampus, 1, 3 or 6 days after injection. Results showed that 3 and 6 days after injection with (PheTe)(2), animals presented loss of body weight and cortical hyperphosphorylation of neurofilament subunits, glial fibrillary acidic protein (GFAP) and vimentin (Vim), the neuronal and glial intermediate filaments, respectively. Otherwise, in hippocampus, only GFAP and Vim were hyperphosphorylated and this effect was evidenced 6 days after injection. In cerebral cortex, hyperphosphorylation was accompanied by increased immunocontent of these proteins both in tissue homogenate and in cytoskeletal fraction, while in hippocampus only the immunocontent of cytoskletal-associated GFAP was increased. Moreover, hyperphosphorylation of cortical IF proteins, induced by (PheTe)(2), was totally reversed by a single subcutaneous injection of diphenyl diselenide (PheSe)(2) (5mumol/kg body weight) 24h after (PheTe)(2) administration. Taken together, our results suggest that cortical cytoskeleton is more susceptible to (PheTe)(2) than hippocampal cytoskeleton. Moreover, cytoskeletal dysfunction in cortical and hippocampal cells could be involved in the neurotoxicity induced by acute treatment with (PheTe)(2).

Over-activation of the Drosophila melanogaster hsp83 gene by selenium intoxication

Selenium is an important dietary micronutrient and an essential component of selenoproteins and the active sites of some enzymes, although at high concentrations it is toxic. We investigated diphenyl diselenide ((C6H5)2Se2 ) for its effects on the developmental stages of Drosophila melanogaster and found that in the larval and pupae stages the toxic threshold for this compound when added to the banana-agar medium on which the larva were fed was 350 µmol. In adult flies, fed on the same media, there were no observable toxic effects below 500 µmol but there were toxic effects above 600 µmol, indicating that adult flies were more resistant to selenium intoxication. In larvae, a when diphenyl diselenide was present above the toxic threshold there was increased activation of the hsp83 heat shock protein gene. Selenium promotes oxidation of sulfhydryl groups and affects the folding of proteins and this could explain the over-expression of hsp83 because the product of this gene is involved in protein folding and defense responses, including the response to heat shock.