Waterborne atenolol disrupts neurobehavioral and neurochemical responses in adult zebrafish.

Environmental contamination by pharmaceuticals from industrial waste and anthropogenic activities poses adverse health effects on non-target organisms. We evaluated the neurobehavioral and biochemical responses accompanying exposure to ecological relevant concentrations of atenolol (0, 0.1, 1.0, and 10 µg/L) for seven uninterrupted days in adult zebrafish (Danio rerio). Atenolol-exposed fish exhibited anxiety-like behavior, characterized by significant bottom-dwelling with marked reduction in vertical exploration. Atenolol-exposed fish exhibited marked increase in the duration and frequency of aggressive events without altering their preference for conspecifics. Biochemical data using brain samples indicated that atenolol disrupted antioxidant enzyme activities and induced oxidative stress. Exposure to atenolol markedly decreased ATP and AMP hydrolysis without affecting ADP hydrolysis and acetylcholinesterase (AChE) activity. Atenolol significantly upregulated tryptophan hydroxylase 1 (tph1) mRNA expression but downregulated brain-derived neurotrophic factor (bdnf) mRNA. Collectively, waterborne atenolol elicits aggressive and anxiety-like responses in adult zebrafish, accompanied by oxidative stress, reduced nucleotide hydrolysis, altered tph1 and bdnf mRNA expression, which may impact the survival and health of fish in aquatic environment.

Negative impacts of social isolation on behavior and neuronal functions are recovered after short-term social reintroduction in zebrafish.

Recently, social isolation measures were crucial to prevent the spread of the coronavirus pandemic. However, the lack of social interactions affected the population mental health and may have long-term consequences on behavior and brain functions. Here, we evaluated the behavioral, physiological, and molecular effects of a social isolation (SI) in adult zebrafish, and whether the animals recover such changes after their reintroduction to the social environment. Fish were submitted to 12 days of SI, and then reintroduced to social context (SR). Behavioral analyses to evaluate locomotion, anxiety-like and social-related behaviors were performed after SI protocol, and 3 and 6 days after SR. Cortisol and transcript levels from genes involved in neuronal homeostasis (c-fos, egr, bdnf), and serotonergic (5-HT) and dopaminergic (DA) neurotransmission (thp, th) were also measured. SI altered social behaviors in zebrafish such as aggression, social preference, and shoaling. Fish submitted to SI also presented changes in the transcript levels of genes related to neural activity, and 5-HT/DA signaling. Interestingly, most of the behavioral and molecular changes induced by SI were not found again 6 days after SR. Thus, we highlight that SR of zebrafish to their conspecifics played a positive role in social behaviors and in the expression of genes involved in different neuronal signaling pathways that were altered after 12 days of SI. This study brings unprecedented data on the effects of SR in the recovery from SI neurobehavioral alterations, and reinforces the role of zebrafish as a translational model for understanding the neurobiological mechanisms adjacent to SI and resocialization.

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+.

Effect of Solanum vegetables on memory index, redox status, and expressions of critical neural genes in Drosophila melanogaster model of memory impairment.

African eggplant (Solanum macrocarpon L) (AE) and Black Nightshade (Solanum nigrum L) (BN) leaves are green leafy vegetables with nutritional and ethnobotanical values. We have previously characterized the vegetables via HPLC/LC-MS to reveal notable phenolic acids, flavonoids and alkaloids. In this present study, we addressed the efficacy of the two vegetables in mitigating mercuric chloride (HgCl2)-induced neurotoxicity and memory impairment in Drosophila melanogaster. Flies were exposed to HgCl2 (0.30 mg/g) alone or in combination with the vegetables (0.1 and 1.0%) of both samples in their diets for seven days. The results showed that HgCl2 (Hg)-exposed flies had significantly reduced survival rate and memory index, which were ameliorated in the Hg-exposed flies fed AE or BN. This was accompanied by increased reactive oxygen species (ROS) levels, reduced total thiol, as well as catalase, glutathione transferase (GST) and acetylcholine esterase (AChE) activities in Hg-exposed fly heads, but ameliorated in Hg-exposed flies fed dietary inclusions of the vegetables. In addition, the Hg-induced alterations in SOD, NF-ҝB/Relish, Dronc and Reaper mRNA levels were statistically indistinguishable from controls in Hg-treated flies fed diets containing AE or BN. Normalization of cnc/Nrf2 and FOXO were observed only in Hg-treated flies fed BN. These findings suggest that dietary AE or BN leaves offer protection against Hg-induced memory impairment and neurotoxicity in D. melanogaster, and further justify them as functional foods with neuroprotective properties.

Dietary inclusions of Solanum vegetables mitigate aluminum-induced redox and inflammation-related neurotoxicity in Drosophila melanogaster model.

BACKGROUND: This study investigated the modulatory capacity of two Solanum green leafy vegetables; S. macrocarpon L. (African eggplant AE) and S. nigrum L. (Black nightshade BN) on dysregulation of some antioxidant, pro-apoptotic, pro-inflammatory-like, acetylcholinesterase gene expression and redox status in the Drosophila melanogaster model of aluminum-induced neurotoxicity. METHODS: Flies were exposed to AlCl3 (6.7 mM) alone or in combination with the leaves (0.1 and 1.0%) from both samples in their diet for seven days. Thereafter, the fly heads were rapidly separated, homogenized, and used to assay for reactive oxygen species (ROS), total thiol content, catalase, glutathione-S-transferase (GST), acetylcholinesterase (AChE) activities, and the expression of antioxidant-mediators (Hsp70, catalase, cnc/Nrf2, Jafrac1 and FOXO), acetylcholinesterase (Ace1), pro-apoptotic caspase-like (Dronc) and its regulator (reaper), as well as inflammation-related (NF-kB/Relish) genes. RESULTS: Results showed that AlCl3-exposed flies had significantly reduced survival rate which were ameliorated by AlCl3 also elevated ROS, GST and reduced AChE activities in fly heads while dietary inclusions of AE and BN ameliorated survial rate and oxidative stress in AlCl3-exposed flies. In addition, Hsp70, Jafrac1, reaper and NF-kҝB/Relish were significantly upregulated in AlCl3-exposed fly heads, while cnc/Nrf2 and FOXO were significantly downregulated, but catalase, Dronc and Ace were, not significantly modulated. Nevertheless, these impairments in gene expression levels were ameliorated by dietary inclusions of AE and BN during AlCl3 exposure. CONCLUSION: These findings showed that dietary inclusions of AE and BN leaves offer protection against Al-induced neurotoxicity in D. melanogaster and thus, could serve as functional foods with neuroprotective properties.

Toxicology and pharmacology of synthetic organoselenium compounds: an update.

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Modulation of redox and insulin signaling underlie the anti-hyperglycemic and antioxidant effects of diphenyl diselenide in zebrafish.

The organic selenium compound diphenyl diselenide (DD) has been recognized as an antioxidant and neuroprotective agent, exerting an anti-hyperglycemic effect in experimental models of diabetes. However, the precise mechanisms involved in the protection are unclear. Using the zebrafish (Danio rerio) as a model organism, here we investigated biomarkers underlying the protective effects of DD against hyperglycemia, targeting in a transcriptional approach the redox and insulin-signaling pathway. Fish were fed on a diet containing DD (3 mg/kg) for 74 days. In the last 14 days, they were exposed to a 111 mM glucose solution to induce a hyperglycemic state. DD reduced blood glucose levels as well as normalized the brain mRNA transcription of four insulin receptors-coding genes (Insra1, Insra2, Insrb1, Insrb2), which were down-regulated by glucose. DD alone caused an up-regulation of relative mRNA transcription in both Insra receptors and glucose transporter 3 genes. DD counteracted hyperglycemia-induced lipid peroxidation, protein and thiol depletion. Along with the decreased activity of antioxidant enzymes SOD and GPx, the brain of hyperglycemic fish presented a reduction in mRNA transcription of FoxO3A, FoxO3B, Nrf2, GPx3A, SOD1, and SOD2 genes. Besides normalizing the transcriptional levels, DD caused an up-regulation of relative mRNAs that encode Nrf2, FoxO1A, FOXO3A, GPx4A, PTP1B, AKT and SelP. Collectively, our findings suggest that the antioxidant and anti-hyperglycemic actions of DD in a zebrafish diabetes model are likely associated with the regulation of the oxidative stress resistance and the insulin-signaling pathway and that could be related to the modulation at mRNA level of two important transcription factors, Nrf2 and FoxO.

Methyl and Ethylmercury elicit oxidative stress and unbalance the antioxidant system in Saccharomyces cerevisiae.

Methylmercury (MeHg) and Ethylmercury (EtHg) are toxic to the central nervous system. Human exposure to MeHg and EtHg results mainly from the consumption of contaminated fish and thimerosal-containing vaccines, respectively. The mechanisms underlying the toxicity of MeHg and EtHg are still elusive. Here, we compared the toxic effects of MeHg and EtHg in Saccharomyces cerevisiae (S. cerevisiae) emphasizing the involvement of oxidative stress and the identification of molecular targets from antioxidant pathways. Wild type and mutant strains with deleted genes for antioxidant defenses, namely: γ-glutamylcysteine synthetase, glutathione peroxidase, catalase, superoxide dismutase, mitochondrial peroxiredoxin, cytoplasmic thioredoxin, and redox transcription factor Yap1 were used to identify potential pathways and proteins from cell redox system targeted by MeHg and EtHg. MeHg and EtHg inhibited cell growth, decreased membrane integrity, and increased the granularity and production of reactive species (RS) in wild type yeast. The mutants were predominantly less tolerant of mercurial than wild type yeast. But, as the wild strain, mutants exhibited higher tolerance to MeHg than EtHg. Our results indicate the involvement of oxidative stress in the cytotoxicity of MeHg and EtHg and reinforce S. cerevisiae as a suitable model to explore the mechanisms of action of electrophilic toxicants.

Taurine Protects from Pentylenetetrazole-Induced Behavioral and Neurochemical Changes in Zebrafish.

Epilepsy is a common neurological disorder characterized by recurrent unprovoked seizures, which culminate in various neurobehavioral and neurochemical changes. Taurine (TAU) is an amino sulfonic acid which acts an endogenous inhibitory neuromodulator. Moreover, TAU displays intrinsic antioxidant activity, contributing to its beneficial actions in the CNS. Here, we evaluated whether TAU pretreatment protects from pentylenetetrazole (PTZ)-induced behavioral alterations and oxidative stress-related parameters in zebrafish brain tissue. Fish were pretreated with 42, 150, and 400 mg/L TAU (40 min) and further exposed to 10 mM PTZ (20 min) to analyze the seizure-like behaviors. As a positive control, another group was previously treated with 75 µM diazepam (DZP). Afterwards, biochemical experiments were performed. All TAU concentrations tested decreased seizure intensity in the first 150 s. Importantly, 150 mg/L TAU attenuated seizure-like behavioral scores, decreased seizure intensity, reduced the frequency of clonic-like seizures (score 4), and increased the latency to score 4. TAU (150 mg/L) also prevented oxidative stress in PTZ-challenged fish by decreasing lipid peroxidation and protein carbonylation and preventing changes on nonprotein thiol levels. No significant changes were observed in MTT assay and LDH activity. Differently than observed in DZP group, TAU did not affect the overall swimming activity of fish, suggesting different mechanisms of action. Collectively, we show that TAU attenuates PTZ-induced seizure-like behaviors and brain oxidative stress in zebrafish, suggesting the involvement of antioxidant mechanisms in neuroprotection.

Hyperglycemia elicits anxiety-like behaviors in zebrafish: Protective role of dietary diphenyl diselenide.

Diabetes mellitus (DM) is a chronic metabolic disease that may comorbid with various psychiatric disorders, such as anxiety and depression. The search for effective therapeutics to alleviate hyperglycemia and complications resulting from DM is continuous. Here we investigate the effects of diphenyl diselenide (DD), an organoselenium compound with several pharmacological properties, in a zebrafish model of hyperglycemia. Fish were fed for 74 days with a diet containing 3 mg/Kg DD, a concentration chosen after experiments based in a dose-response curve (DD 1, 2 and 3 mg/Kg) that did not cause overt toxicity (mortality, weight loss and neurobehavioral deficits). In the last 14 days of the experimental period, fish were concomitantly exposed to a glucose solution (111 mM). Afterwards, blood glucose levels, brain selenium (Se) content, and behavioral analysis aiming to assess anxiety-like behaviors and locomotor/exploratory activities were performed. In the novel tank diving test, glucose decreased vertical exploration and fish spent less time in the lit area when tested in the light-dark test, suggesting increased anxiety-like behavior. Moreover, DD decreased blood glucose levels in hyperglycemic fish as well as prevented the development of anxiety-related symptoms. DD diet alone did not change glycemia and behavioral parameters, but increased Se levels in the brain without affecting the cellular viability. Collectively, our findings highlight the growing utility of this zebrafish hyperglycemia model as a valuable strategy for further research in DM field and neuroprotective approaches.

Extending the analysis of zebrafish behavioral endophenotypes for modeling psychiatric disorders: Fear conditioning to conspecific alarm response.

Anxiety, trauma- and stressor-related disorders are severe psychiatric conditions that affect human population worldwide. Given their genetic tractability, evolutionarily conserved neurotransmitter systems, and extensive behavioral repertoire, zebrafish have become an emergent model organism in translational neuroscience. Here, we investigate whether a single exposure to conspecific alarm substance (CAS) produces fear conditioning in zebrafish using a conditioned place aversion (CPA) paradigm, as well as the persistence of aversive responses at different time intervals. While CAS elicited freezing and erratic movements at conditioning phase, zebrafish showed a robust avoidance for the CAS-paired compartment and increased risk assessment up to 7 days postconditioning. Additionally, we observed the existence of two behavioral phenotypes (high- and low-avoider fish) that present different fear-like responses at conditioning phase and evasion of the conditioning side at postconditioning trials. Collectively, we show a prolonged conditioned place aversion in zebrafish after a single CAS conditioning session, reinforcing the use of fear conditioning protocols as valuable strategies for modeling psychiatric disorders-related phenotypes in zebrafish.

Syzygium cumini leaf extract inhibits LDL oxidation, but does not protect the liproprotein from glycation.

ETNOPHARMACOLOGICAL RELEVANCE: Syzygium cumini (L.) Skeels is a plant widely used in folk medicine to treat diabetes mellitus (DM). The tea from its leaves is frequently used by diabetics for lowering hyperglycemia. There is a close relationship between DM and atherosclerosis, a chronic immuno-inflammatory disease, were the early stages encompass oxidative and glycative modifications in the structure of low density lipoprotein (LDL). AIM OF THIS STUDY: To investigate the potential protective effects of aqueous-leaf extract from Syzygium cumini (S.cExt) against CuSO4-induced oxidation and methylglyoxal (MG)-induced glycation of human LDL in vitro. MATERIALS AND METHODS: LDL oxidative changes were evaluated by measuring conjugated dienes (CD) formation, thiobarbituric acid reactive substances (TBARS) levels, quenching of tryptophan (Trp) fluorescence and structural modifications in LDL particle. In LDL glycated by MG (glyLDL), we determined the levels of fluorescent advanced glycation end products (AGEs) and mobility by agarose gel electrophoresis. RESULTS: S.cExt blocked oxidative events induced by CuSO4 in human LDL, plasma and serum. Fourier transform infrared spectroscopy (FT-IR) revealed that specific regions of apoB100 were oxidized by CuSO4 in human LDL and that S.cExt reduced these oxidations. Unlike, the increased AGEs levels and eletrophoretic mobility observed in LDL MG-glycated were not modified by S.cExt. CONCLUSION: The findings herein indicate that S.cExt could be tested in atherogenesis models as potential protective agent against LDL oxidation.

Organoselenium compounds as mimics of selenoproteins and thiol modifier agents.

Selenium is an essential trace element for animals and its role in the chemistry of life relies on a unique functional group: the selenol (-SeH) group. The selenol group participates in critical redox reactions. The antioxidant enzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) exemplify important selenoproteins. The selenol group shares several chemical properties with the thiol group (-SH), but it is much more reactive than the sulfur analogue. The substitution of S by Se has been exploited in organic synthesis for a long time, but in the last 4 decades the re-discovery of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) and the demonstration that it has antioxidant and therapeutic properties has renovated interest in the field. The ability of ebselen to mimic the reaction catalyzed by GPx has been viewed as the most important molecular mechanism of action of this class of compound. The term GPx-like or thiol peroxidase-like reaction was previously coined in the field and it is now accepted as the most important chemical attribute of organoselenium compounds. Here, we will critically review the literature on the capacity of organoselenium compounds to mimic selenoproteins (particularly GPx) and discuss some of the bottlenecks in the field. Although the GPx-like activity of organoselenium compounds contributes to their pharmacological effects, the superestimation of the GPx-like activity has to be questioned. The ability of these compounds to oxidize the thiol groups of proteins (the thiol modifier effects of organoselenium compounds) and to spare selenoproteins from inactivation by soft-electrophiles (MeHg+, Hg2+, Cd2+, etc.) might be more relevant for the explanation of their pharmacological effects than their GPx-like activity. In our view, the exploitation of the thiol modifier properties of organoselenium compounds can be harnessed more rationally than the use of low mass molecular structures to mimic the activity of high mass macromolecules that have been shaped by millions to billions of years of evolution.

Scientific Performance of Brazilian Researchers in Pharmacology with grants from CNPq: A comparative study within the Brazilian categories.

In Brazil, scientific performance of researchers is one important criteria for decision-making in grant allocation. In this context, this study aimed to evaluate and compare the profile of 82 seniors' investigators (graded as level 1A-D) which were receiving CNPq (National Council for Scientific and Technological Development) productivity grant in Pharmacology, by analyzing the pattern of citation of their papers and h-index. Total documents, citations (with and without self-citations) and h-index (with and without self-citations) were retrieved from the Scopus database. The results indicated a clear difference among researchers from the higher categories (1A and 1B) in most of the parameters analyzed. However, no noticeable differentiation was found between researchers from grant category 1C and 1D. The results presented here may inform the scientific community and the grant agencies on the profile of PQ 1(A-D) fellows of Pharmacology, and may help to define new differences within CNPq grant categories, and consequently, a better allocation of grants.

Therapeutic cold: An effective kind to modulate the oxidative damage resulting of a skeletal muscle contusion.

Muscular contusions affect the function of the skeletal muscle system. This study investigated the oxidative damage as well as the main morphological changes related to a skeletal muscle contusion in the gastrocnemius muscle of rats and also the capacity of therapeutic cold to modulate these parameters. The therapeutic cold modulated the increase of oxidative stress markers and also modulated the reduction in the antioxidants levels in the injured muscle. In enzyme assays, therapeutic cold was also effective in normalizing the muscle Na(+)/K(+) and Ca(2+) ATPases, lactate dehydrogenase and myeloperoxidase activities. Similarly, the lesioned non-treated animals presented evident impairments in the mitochondrial functions and in the muscle morphology which were diminished by the cold treatment. The therapeutic cold was able to modulate the oxidative damage possibly by its capacity to limit the inflammatory response intensity, to attenuate the impairment of the mitochondrial function and also to preserve the skeletal muscle morphology.