Carlos Eduardo Leite

Behavioral effects of taurine pretreatment in zebrafish acutely exposed to ethanol.

Taurine (TAU) is an amino sulfonic acid that plays protective roles against neurochemical impairments induced by ethanol (EtOH). Mounting evidence shows the applicability of zebrafish for evaluating locomotor parameters and anxiety-like behavioral phenotypes after EtOH exposure in a large scale manner. In this study, we assess the effects of TAU pretreatment on the behavior of zebrafish in the open tank after acute 1% EtOH (v/v) exposure (20 and 60 min of duration) and on brain alcohol contents. The exposure for 20 min exerted significant anxiolytic effects, which were prevented by 42, 150, and 400 mg/L TAU. Conversely, the 60-min condition induced depressant/sedative effects, in which the changes on vertical activity were associated to modifications on the exploratory profile. Although all TAU concentrations kept locomotor parameters at basal levels, 150 mg/L TAU, did not prevent the impairment on vertical activity of EtOH[60]. Despite the higher brain EtOH content detected in the 60-min exposure, 42, 150, and 400 mg/L TAU attenuated the increase of alcohol content in EtOH[60] group. In conclusion, our data suggest that both protocols of acute EtOH exposure induce significant changes in the spatio-temporal behavior of zebrafish and that TAU may exert a preventive role by antagonizing the effects induced by EtOH possibly due to its neuromodulatory role and also by decreasing brain EtOH levels. The hormetic dose-response of TAU on vertical exploration suggests a complex interaction between TAU and EtOH in the central nervous system.

Anti-inflammatory effects of red pepper (Capsicum baccatum) on carrageenan- and antigen-induced inflammation.

Inflammation is a pivotal component of a variety of diseases, such as atherosclerosis and tumour progression. Various naturally occurring phytochemicals exhibit anti‐inflammatory activity and are considered to be potential drug candidates against inflammation‐related pathological processes. Capsicum baccatum L. var. pendulum (Willd.) Eshbaugh (Solanaceae) is the most consumed species in Brazil, and its compounds, such as capsaicinoids, have been found to inhibit the inflammatory process. However, the anti‐inflammatory effects of C. baccatum have not been characterized. Thus, this study was designed to evaluate the effects of C. baccatum juice in animal models of acute inflammation induced by carrageenan and immune inflammation induced by methylated bovine serum albumin. Pretreatment (30 min) of rats with pepper juice (0.25–2.0 g kg−1) significantly decreased leucocyte and neutrophil migration, exudate volume and protein and LDH concentration in pleural exudates of a pleurisy model. This juice also inhibited neutrophil migration and reduced the vascular permeability on carrageenan‐induced peritonitis in mice. C. baccatum juice also reduced neutrophil recruitment and exudate levels of pro‐inflammatory cytokines TNF‐α and IL‐1β in mouse inflammatory immune peritonitis. Furthermore, we demonstrated that the main constituent of C. baccatum juice, as extracted with chloroform, is capsaicin. In agreement with this, capsaicin was able to inhibit the neutrophil migration towards the inflammatory focus. To our knowledge, this is the first demonstration of the anti‐inflammatory effect of C. baccatum juice and our data suggest that this effect may be induced by capsaicin. Moreover, the anti‐inflammatory effect induced by red pepper may be by inhibition of pro‐inflammatory cytokine production at the inflammatory site.

Rimonabant: an antagonist drug of the endocannabinoid system for the treatment of obesity

Obesity, an ever-increasing problem in the industrialized world, has long been a target of research for a cure or, at least, control of its expansion. In the search for treatment, the recently discovered endocannabinoid system has emerged as a new target for controlling obesity and its associated conditions. The endocannabinoid system plays an important role in controlling weight and energy balance in humans. This system is activated to a greater extent in obese patients, and the specific blockage of its receptors is the aim of rimonabant, one of the most recent drugs created for the treatment of obesity. This drug acts as a blockade for endocannabinoid receptors found in the brain and peripheral organs that play an important role on carbohydrate and fat metabolism. Clinical studies have confirmed that, when used in combination with a low calorie diet, rimonabant promotes loss in body weight, loss in abdominal circumference, and improvements in dyslipidemia. Rimonabant is also being tested as a potential anti-smoking treatment since endocannabinoids are related to the pleasurable effect of nicotine. Thus, rimonabant constitutes a new therapeutic approach to obesity and cardiovascular risk factors. Studies show effectiveness in weight loss; however, side effects such as psychiatric alterations have been reported, including depression and anxiety. These side effects have led the FDA (Food and Drug Administration) to not approve this drug in the United States. For a more complete evaluation on the safety of this drug, additional studies are in progress.

Seizures Induced by Pentylenetetrazole in the Adult Zebrafish: A Detailed Behavioral Characterization

Pentylenetetrazole (PTZ) is a common convulsant agent used in animal models to investigate the mechanisms of seizures. Although adult zebrafish have been recently used to study epileptic seizures, a thorough characterization of the PTZ-induced seizures in this animal model is missing. The goal of this study was to perform a detailed temporal behavior profile characterization of PTZ-induced seizure in adult zebrafish. The behavioral profile during 20 min of PTZ immersion (5, 7.5, 10, and 15 mM) was characterized by stages defined as scores: (0) short swim, (1) increased swimming activity and high frequency of opercular movement, (2) erratic movements, (3) circular movements, (4) clonic seizure-like behavior, (5) fall to the bottom of the tank and tonic seizure-like behavior, (6) death. Animals exposed to distinct PTZ concentrations presented different seizure profiles, intensities and latencies to reach all scores. Only animals immersed into 15 mM PTZ showed an increased time to return to the normal behavior (score 0), after exposure. Total mortality rate at 10 and 15 mM were 33% and 50%, respectively. Considering all behavioral parameters, 5, 7.5, 10, and 15 mM PTZ, induced seizures with low, intermediate, and high severity, respectively. Pretreatment with diazepam (DZP) significantly attenuated seizure severity. Finally, the brain PTZ levels in adult zebrafish immersed into the chemoconvulsant solution at 5 and 10 mM were comparable to those described for the rodent model, with a peak after a 20-min of exposure. The PTZ brain levels observed after 2.5-min PTZ exposure and after 60-min removal from exposure were similar. Altogether, our results showed a detailed temporal behavioral characterization of a PTZ epileptic seizure model in adult zebrafish. These behavioral analyses and the simple method for PTZ quantification could be considered as important tools for future investigations and translational research.

Effects of D-series resolvins on behavioral and neurochemical changes in a fibromyalgia-like model in mice.

This study investigated whether the spinal or systemic treatment with the lipid resolution mediators resolvin D1 (RvD1), aspirin-triggered resolvin D1 (AT-RvD1) and resolvin D2 (RvD2) might interfere with behavioral and neurochemical changes in the mouse fibromyalgia-like model induced by reserpine. Acute administration of AT-RvD1 and RvD2 produced a significant inhibition of mechanical allodynia and thermal sensitization in reserpine-treated mice, whereas RvD1 was devoid of effects. A similar antinociceptive effect was obtained by acutely treating animals with the reference drug pregabalin. Noteworthy, the repeated administration of AT-RvD1 and RvD2 also prevented the depressive-like behavior in reserpine-treated animals, according to assessment of immobility time, although the chronic administration of pregabalin failed to affect this parameter. The induction of fibromyalgia by reserpine triggered a marked decrease of dopamine and serotonin (5-HT) levels, as examined in total brain, spinal cord, cortex and thalamus. Reserpine also elicited a reduction of glutamate levels in total brain, and a significant increase in the spinal cord and thalamus. Chronic treatment with RvD2 prevented 5-HT reduction in total brain, and reversed the glutamate increases in total brain and spinal cord. Otherwise, AT-RvD1 led to a recovery of dopamine levels in cortex, and 5-HT in thalamus, whilst it diminished brain glutamate contents. Concerning pregabalin, this drug prevented dopamine reduction in total brain, and inhibited glutamate increase in brain and spinal cord of reserpine-treated animals. Our data provide novel evidence, showing the ability of D-series resolvins AT-RvD1, and mainly RvD2, in reducing painful and depressive symptoms allied to fibromyalgia in mice.

Cotinine as a biomarker of tobacco exposure: development of a HPLC method and comparison of matrices.

Tobacco dependence reaches one-third of the world population, and is the second leading cause of death around the world. Cotinine, a major metabolite of nicotine, is the most appropriate parameter to evaluate tobacco exposure and smoking status due to its higher stability and half-life when compared to nicotine. The procedure involves liquid-liquid extraction, separation on a RP column (Zorbax XDB C(8)), isocratic pump (0.5 mL/min of water-methanol-sodium acetate (0.1 M)-ACN (50:15:25:10, v/v/v/v), 1.0 mL of citric acid (0.034 M) and 5.0 mL of triethylamine for each liter) and HPLC-UV detection (261 nm). The analytical procedure proved to be sensitive, selective, precise, accurate and linear (r>0.99) in the range of 5-500.0 ng/mL for cotinine. 2-Phenylimidazole was used as the internal standard. The LOD was 0.18 ng/mL and the LOQ was 5.0 ng/mL. All samples from smoking volunteers were collected simultaneously to establish a comparison between serum, plasma, and urine. The urinary cotinine levels were normalized by the creatinine and urine density. A significant correlation was found (p<0.01) between all matrices. Results indicate that the urine normalization by creatinine or density is unnecessary. This method is considered reliable for determining cotinine in serum and plasma of smokers and in environmental tobacco smoke exposure.

The effects of fructose-1,6-bisphosphate and dexamethasone on acute inflammation and T-cell proliferation

Abstract.Objective and designChronic glucocorticoid treatment is associated with pharmacological resistance. We investigated the auxiliary effects of fructose-1,6-bisphosphate (FBP) on dexamethasone (DEX)-related modulation of inflammation and T-cell proliferation.MethodsAcute inflammation (pleurisy) was induced by injection of carrageenan into the pleural cavity of rats that were treated in vivo with DEX s. c. and FBP i. p. Peripheral blood mononuclear cells were isolated and T-cell sensitivity to FBP and DEX was evaluated in vitro.ResultsFBP and DEX reduced the exudate volume, protein concentration and neutrophils in the pleural cavity. However no synergistic effects were observed when these compounds were tested simultaneously. In contrast, both compounds dose-dependently and synergistically suppressed T-cell proliferation.ConclusionThese data suggest that FBP may be beneficial as auxiliary drug for the treatment of patients with acquired glucocorticoid resistance.

First reported outbreak of green tobacco sickness in Brazil

Dermal absorption of nicotine by people harvesting tobacco may cause an acute intoxication called green tobacco sickness. Although Brazil is the second largest producer of tobacco in the world, green tobacco sickness had not been reported in the country to date. We conducted a 1:1 matched case-control study among persons involved in tobacco farming to determine the occurrence of green tobacco sickness in the northeast region of Brazil and to identify the risk factors involved. A case-patient was a person who received a diagnosis by health professional of acute intoxication during the study period and had a cotinine level over 10 ng/mL detected by High Performance Liquid Chromatography. We identified 107 case-patients. The main signs and symptoms observed were dizziness, weakness, vomit, nausea and headache. Independent risk factors identified were being male, a non smoker and having worked in the harvest of tobacco leaves. Case-patients had higher median urinary cotinine levels than controls (p < 0.05). Epidemiological and laboratory data indicate for the first time the occurrence of green tobacco sickness in Brazil.

Hair Cortisol and Stressful Life Events Retrospective Assessment in Crack Cocaine Users

Background: Some evidence suggests that altered hypothalamic–pituitary–adrenal (HPA) axis functioning in cocaine users might play a role in the pathophysiology of substance abuse. This study aimed to investigate the relationship between exposure to negative life events and cortisol hair concentrations in crack cocaine users during the 3 months prior to admission to a detoxification program. Methods: A total of 23 treatment-seeking, crack cocaine-dependent women were selected for this study 1 week after admission to an inpatient treatment at a locked treatment facility. The Paykel Life Events Scale measured the occurrence of stressful life events 3 months before admission. Hair cortisol concentration was measured during these three previous months. Results: The partial correlations, using severity of dependence as control variable, revealed that there is a positive association between hair cortisol concentration and the number of negative life events exposure 90 days (r = .56; p = .007) and 30 days (r = .42; p = .048) prior to admission at the hospital. One-way ANOVA suggests that hair cortisol levels and stress load significantly increase over 3 months prior to hospitalization. Conclusions: The results of this study indicate that there is a positive association between measures of long-term cumulative cortisol secretion and the number of stressful events reported by women receiving inpatient treatment for crack cocaine dependence. Therefore, this study suggests that stress load can be objectively quantified and noninvasively assessed. Scientific Significance: This study is the first to investigate HPA axis functioning using hair cortisol concentrations among crack cocaine-dependent users. It is a promising strategy to assess stress load in substance abusers.

Protective Effects of Resveratrol on Hepatotoxicity Induced by Isoniazid and Rifampicin via SIRT1 Modulation

Acute liver injury was induced in male BALB/c mice by coadministering isoniazid and rifampicin. In this work, the effects of resveratrol (1) were investigated in the hepatotoxicity caused by isoniazid-rifampicin in mice. Compound 1 was administered 30 min prior to isoniazid-rifampicin. Serum biochemical tests, liver histopathological examination, oxidative stress, myeloperoxidase activity, cytokine production (TNF-α, IL-12p70, and IL-10), and mRNA expression of SIRT1-7 and PPAR-γ/PGC1-α were evaluated. The administration of 1 significantly decreased aspartate transaminase and alanine aminotransferase levels, myeloperoxidase activity, and cytokine levels. Furthermore, 1 reverted the decrease of catalase and glutathione activities and ameliorated the histopathological alterations associated with antituberculosis drugs. Modulation of SIRT1 and PPAR-γ/PGC1-α expression is likely involved in the protective effects of 1. The results presented herein show that 1 was able to largely prevent the hepatotoxicity induced by isoniazid and rifampicin in mice, mainly by modulating SIRT1 mRNA expression.