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Over the years, scientific research with fish models has grown at a rapid pace, and issues such as animal welfare are becoming increasingly important in various areas of animal husbandry and experimentation. Here, we evaluated whether Danio rerio behavior is affected by long-term maintenance (75 days) in an enriched environment or a chronic stress (CS) situation. In addition, we evaluated some biochemical parameters related to redox status. We concluded that long-term maintenance of zebrafish in enriched environment might induce an anxiety-like behavior pattern when these fish are faced with an acute subsequent stressor. These anxiety results, the increased school cohesion, and the absence of oxidative damage allow us to hypothesize that the fish maintained in environmental enrichment (EE) situation is more reactive, showing a strong protective reaction to the stress. From an applicable perspective, we show that both too much stress and too little stress are not ideal for zebrafish stocks. In CS situations, fish can habituate and might not respond optimally to test conditions. In opposite, the low stress promoted by environmental enrichment also renders the fish incapable of dealing with occasional stressors optimally, because now even normal conditions appear stressful to them and may elicit fear behaviors they normally would not exhibit.

The consumption of hormone-derived medicines, such as levonorgestrel (LNG), is increasing worldwide, and its discharge into the environment reaches non-target organisms. In our previous study, we exposed the parental generation of zebrafish to environmentally relevant concentrations of LNG during the developmental phase. Subsequently, they had grown in a tank with clean water until adulthood. Now, we allowed this parental generation to reproduce to obtain F1 progeny unexposed to LGN, in order to analyze the transgenerational effects of parental LNG exposure on the survival and hatching of unexposed F1 embryos and the stress and behavior of F1 larvae. Here, we found decreased survival rates with higher LNG concentrations, providing a transgenerational effect. This highlights the environmental impact of exposure to LNG, causing damage at the individual and population level and affecting the next generation at the beginning of development, impacting qualities in the survival of the species., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Numerous chemical compounds are found in aquatic environments; among them are pesticides. Pesticides are widely used worldwide, and this use has progressively increased in recent decades, resulting in the accumulation of potentially toxic compounds in surface waters. Dimethylamine-based herbicides (DBH) and imidacloprid-based insecticides (IBI) have low soil absorption and high water solubility, facilitating the arrival of these compounds in aquatic environments. In this study, our objective was to analyze whether two pesticides, DBH and IBI at environmentally relevant concentrations of 320 μg/L for each compound, and their mixtures impact the behavioral and endocrine parameters of adult zebrafish, verifying the effect of pesticides on exploratory behavior and social and analyzing hormonal parameters related to stress. Acute exposure to the mixture of pesticides reduced fish locomotion. Pesticides alone and in combination did not affect cortisol levels in exposed animals. Pesticides, when tested together, can cause different effects on non-target organisms, and the evaluation of mixtures of these compounds is extremely important., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Methylphenidate (MPH) is a central nervous system stimulant that is mainly used for Attention-Deficit/Hyperactivity Disorder (ADHD). It is well known that there is a high rate of ADHD misdiagnosis, leading to a great number of neurotypical children chronically exposed to MPH in early periods of life. This increase raises concern about possible long-lasting effects of this exposure. We aimed to evaluate whether exposure to MPH during childhood might impact adult behavioral pattern. For this purpose, we used zebrafish as a translational model considering its robustness as experimental model and fast life cycle. Fish were exposed during juvenile period (from 30 to 60 post-natal day) at MPH therapeutic concentration (2 mg L -1 ), and behavioral tests were performed at fish adulthood (120 post-natal day). MPH provoked slight anxiolytic-like effects and hyperlocomotion, and no differences on sociability and cortisol levels were observed. Moreover, sex did not affect any of the parameters evaluated. These results demonstrate that early chronic exposure to MPH leads to neurobehavioral adaptations that persist into adulthood in zebrafish regardless of sex, suggesting that the misuse of MPH during childhood and adolescence can alter neurobehavioral plasticity and these alterations might persist until adulthood., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The growing consumption of psychoactive drugs, such as Venlafaxine (VFX), can negatively affect the organisms. Our main hypothesis is to investigate if VFX at human-used doses could exert effects on the behavioral, nervous, and antioxidant systems of two different organisms, zebrafish and C. elegans. We evaluated the effect of acute exposure to VFX at four concentrations (0, 37.5, 75, and 150 mg L -1 ) using toxicological indicator assessments. We evaluated zebrafish behavior using the novel tank test (NTT), social preference test (SPT), cortisol levels, acetylcholinesterase (AChE) activity, and antioxidant system. In C. elegans, we evaluated body bends, defecation cycles, pharyngeal pumping, AChE activity, and antioxidant system. C. elegans do not show alterations in the behavior analysis of pharyngeal pumping and body bends. Instead, the defecation cycle was increased in the highest dose of VFX. AChE activity also does not have differences compared to the control, the same occurs in lipid peroxidation rates. These results showed that nematodes were more resistant to changes when exposed to VFX. Zebrafish exposed to VFX showed changes in the NTT and SPT test, mainly in the anxiolytic pattern, suggesting that VFX alters this anxiolytic-like behavior. Comparing both organisms, we can observe that zebrafish seems to be more sensitive in this neurotoxicological evaluation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The use of agrichemical pyrethroid-based insecticides to combat crop infestations and ectoparasites in animals is increasing. In this context, two pyrethroid-based insecticides are widely used, λ-cyhalothrin and Cypermethrin. The mechanism of action of these insecticides is characterized by the opening of ion channels and death by neural hyperexcitability. In this study, we evaluated the toxicological effect of two pyrethroid-based insecticides λ-cyhalothrin and Cypermethrin in C. elegans aiming to evaluate the transgenerational (TG), neonatal (NN) and lifespan (LS) effects of these compounds. At the end of each exposure period, were evaluated behavioral biomarkers of body bends, pharyngeal pumping, and feeding behavior. Furthermore, the fluorescent expression of antioxidant enzymes (superoxide dismutase, catalase, and glutathione-S-transferase) and the fluorescent expression of PolyQ40 aggregates were quantified. Lastly, the activity of the enzyme acetylcholinesterase (AChE) was quantified. Changes in TG were more related to changes in AChE enzyme activity that probably were transferred to the offspring, altering behavioral biomarkers in the adult life of offspring from exposed parents. However, alterations in LS were related to the modulation of ion channels in a chronic way, exerting behavioral effects. In addition, both compounds increased the expression of PolyQ40 muscle aggregates in mutant worms. These proteins are related to the increased probability of the senile incidence of Huntington's Disease in genetically predisposed patients., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The trade of aquarium organisms is growing worldwide. This market depends on a continuous supply of healthy and colorful aquatic animals, but this sector has few initiatives. However, in the last decade, there has been a growing interest in researching captive breeding of these animals, aiming to develop a more sustainable aquarium hobby. Larviculture is an important phase in the cultivation process because the larvae are more sensitive to stress and variations in the bulk of variables, such as temperature, salinity, nutritional management, light intensity and spectrum, and environmental background colors. Because background color could be a promoter variable of proper welfare, we tested whether it affects the endocrine response of tomato clownfish Amphiprion frenatus larvae to an acute stress challenge. We show that background color influences the endocrine stress axis responsiveness in tomato clownfish. When fish were subjected to a standard acute stressor of 61 days after hatching, only fish adapted to white walls increased the whole-body cortisol levels. From the results presented herein, we recommend that white tanks be avoided for A. frenatus larviculture. Both, the less stress level and the good welfare condition of larvae reared in colored tanks may have robust, practical applications since almost all clownfish in the ornamental aquarium trade come from captive breeding., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

The use of terpenoid compounds in different neural-related conditions is becoming useful for several illnesses. Another possible activity of these compounds is the reduction of nervous impairment. Cannabis sativa plants are known for their concentration of two important terpenoids, the delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). CBD and THC have central peripheral activities already described and their usage in different brain diseases, such as Alzheimer's and multiple sclerosis. Aluminum (Al) is known as an important neurotoxic compound, the physiological action of Al is not known already, and in high concentrations can lead to intoxication and cause neurotoxicity. Here we evaluated the potential effect of two different doses of CBD- and THC-rich based oils against Al-induced toxicity, in the zebrafish model. We evaluated behavioral biomarkers of the novel tank test (NTT) and social preference test (SPT), and biochemical markers: the activity of the enzyme acetylcholinesterase (AChE) and the antioxidant enzymes-catalase, superoxide dismutase, and glutathione-S-transferase. CBD- and THC-based oils were able to increase the AChE activity helping the cholinergic nervous system actuate against Al toxicity which was reflected by the behavioral biomarkers changes. We concluded that the oils have a protective effect and might be used with proposals for neurological and antioxidant impairment avoidance caused by Al intoxications., (© 2023. The Author(s).)

The imidacloprid-based insecticides (IBIs) are among the most used insecticides worldwide, and chronic and acute toxic effects (days exposure protocols) have been reported in several species in studies of IBIs at lethal concentrations. However, there is little information on shorter time exposures and environmentally relevant concentrations. In this study, we investigated the effect of a 30-min exposure to environmentally relevant concentrations of IBI on the behavior, redox status, and cortisol levels of zebrafish. We showed that the IBI decreased fish locomotion and social and aggressive behaviors and induced an anxiolytic-like behavior. Furthermore, IBI increased cortisol levels and protein carbonylation and decreased nitric oxide levels. These changes were mostly observed at 0.013 and 0.0013 µg·L -1 of IBI. In an environmental context, these behavioral and physiological disbalances, which were immediately triggered by IBI, can impair the ability of fish to evade predators and, consequently, affect their survival., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Despite all efforts to combat the pandemic of COVID-19, we are still living with high numbers of infected persons, an overburdened health care system, and the lack of an effective and definitive treatment. Understanding the pathophysiology of the disease is crucial for the development of new technologies and therapies for the best clinical management of patients. Since the manipulation of the whole virus requires a structure with an adequate level of biosafety, the development of alternative technologies, such as the synthesis of peptides from viral proteins, is a possible solution to circumvent this problem. In addition, the use and validation of animal models is of extreme importance to screen new drugs and to compress the organism's response to the disease. Peptides derived from recombinant S protein from SARS-CoV-2 were synthesized and validated by in silico, in vitro and in vivo methodologies. Macrophages and neutrophils were challenged with the peptides and the production of inflammatory mediators and activation profile were evaluated. These peptides were also inoculated into the swim bladder of transgenic zebrafish larvae at 6 days post fertilization (dpf) to mimic the inflammatory process triggered by the virus, which was evaluated by confocal microscopy. In addition, toxicity and oxidative stress assays were also developed. In silico and molecular dynamics assays revealed that the peptides bind to the ACE2 receptor stably and interact with receptors and adhesion molecules, such as MHC and TCR, from humans and zebrafish. Macrophages stimulated with one of the peptides showed increased production of NO, TNF-α and CXCL2. Inoculation of the peptides in zebrafish larvae triggered an inflammatory process marked by macrophage recruitment and increased mortality, as well as histopathological changes, similarly to what is observed in individuals with COVID-19. The use of peptides is a valuable alternative for the study of host immune response in the context of COVID-19. The use of zebrafish as an animal model also proved to be appropriate and effective in evaluating the inflammatory process, comparable to humans., (© 2023. The Author(s).)

Pyrethroid-based insecticides are largely used for mosquito control. These compounds have household and agricultural applications with different formulations. Two important compounds used as household insecticides are prallethrin and transfluthrin, both from the pyrethroid chemical group. With the mode of action centered on sodium channels, pyrethroids keep the ionic sodium channels open for a long time causing the death of the insect by nervous hyperexcitability. Given the increased use of household insecticides by humans and the incidence of disease outbreaks with unknown etiology such as autism spectrum disease, schizophrenia, and Parkinson's disease we investigate some physiological inputs of these compounds on zebrafish. In this study, we evaluated the social interaction, shoaling formation, and anxiety-like behavior of zebrafish exposed chronically to transfluthrin- and prallthrin-based insecticides (T-BI and P-BI). In addition, we quantified the activity of the enzyme acetylcholinesterase (AChE) in different brain regions. We observed that both compounds caused anxiolytic behavior and reduced shoaling formation and social interaction. Their behavioral biomarkers indicated a harmful ecological effect on the specie as well as a possible impact of these compounds on autism spectrum disorder (ASD) and schizophrenia (SZP). In addition, the AChE activity would change its activity in different brain regions modulating the anxiety-like behavior and social behavior in zebrafish. We conclude that P-BI and T-BI make us alert about the relationship of these compounds with nervous diseases related to cholinergic signaling., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Although the exact mechanism of the pathogenesis of coronavirus SARS-CoV-2 (COVID-19) is not fully understood, oxidative stress and the release of pro-inflammatory cytokines have been highlighted as playing a vital role in the pathogenesis of the disease. In this sense, alternative treatments are needed to reduce the level of inflammation caused by COVID-19. Therefore, this study aimed to investigate the potential effect of red photobiomodulation (PBM) as an attractive therapy to downregulate the cytokine storm caused by COVID-19 in a zebrafish model. RT-qPCR analyses and protein-protein interaction prediction among SARS-CoV-2 and Danio rerio proteins showed that recombinant Spike protein (rSpike) was responsible for generating systemic inflammatory processes with significantly increased levels of pro-inflammatory ( il1b , il6 , tnfa , and nfkbiab ), oxidative stress ( romo1 ) and energy metabolism ( slc2a1a and coa1 ) mRNA markers, with a pattern similar to those observed in COVID-19 cases in humans. On the other hand, PBM treatment was able to decrease the mRNA levels of these pro-inflammatory and oxidative stress markers compared with rSpike in various tissues, promoting an anti-inflammatory response. Conversely, PBM promotes cellular and tissue repair of injured tissues and significantly increases the survival rate of rSpike-inoculated individuals. Additionally, metabolomics analysis showed that the most-impacted metabolic pathways between PBM and the rSpike treated groups were related to steroid metabolism, immune system, and lipid metabolism. Together, our findings suggest that the inflammatory process is an incisive feature of COVID-19 and red PBM can be used as a novel therapeutic agent for COVID-19 by regulating the inflammatory response. Nevertheless, the need for more clinical trials remains, and there is a significant gap to overcome before clinical trials can commence.

Different classes of insecticide compounds have been employed to control insects and mosquitoes; Pyrethroids are one of the most common used in both urban and rural household environments. This study investigated the effects of exposure of two doses of commercial transfluthrin-based insecticide (T-BI) on behavior (body bends, pharyngeal pumping rate, and feeding attributes) and biochemical biomarkers (AChE, PolyQ40 aggregations, HSP, antioxidative SOD, CTL, and GST) following three different protocols (transgenerational, neonatal, and lifespan) in Caenorhabditis elegans model system. The relative calculated dose (RCD) and relative calculated half dose (RCHD) of T-BI were compared with those of the control (water). T-BI reduced the health span of worms treated during their whole life and changed biochemical and behavioral patterns due to progenitors' uterine (transgenerational) and neonatal exposures. It was inferred that the effects of T-BI are transgenerational and persistent and can be harmful to non-target species, including humans. In addition, our findings highlight that T-BI contact by progenitors accelerates the establishment of Huntington's disease and causes a cholinergic outbreak in offspring adulthood., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Highly toxic chemical compounds are present in rivers and lakes, endangering the survival of non-target species. To evaluate the effects of environmental contamination on non-target species, we used the zebrafish as an animal model. Environmental concentrations of the widely used pesticides, glyphosate (GBH) at 4.8 μg·L -1 and 2,4-dichlorophenoxyacetic acid (DBH) at 3.4 μg·L -1 , were used. The animals were exposed during the entire period of organogenesis and evaluated in our previous study regarding initial developmental parameters. In the present study, we evaluate these fish when achieve the adult phase, using the novel tank test (NTT) and the aversivity test. In the second step, the animals were allowed to reproduce, and the initial parameters of development, behavioral parameters in the open field test (OFT) and in the aversivity test (AST), and biochemical biomarkers as acetylcholinesterase (AChE), catalase (CAT), and superoxide dismutase (SOD) in the F1 generation were studied. Fish exposed to GBH showed hypermobility, and their anti-predatory reaction was impaired during adulthood, indicating a persistent effect. We also showed that fish had impaired behavioral and survival changes in the F1 generation as well as effects on AChE activity and antioxidant enzymes, characterizing a transgenerational effect. The fish did not show persistent effects in adulthood due to DBH exposure; however, they were unable to reproduce. Our findings demonstrate the serious impact of pesticides on fish, where the effects of contamination can affect future generations and compromise the species' survival., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Household insecticide is largely used for insect and ectoparasite control, in city centers as well as in the countryside. The pyrethroids are the most used class of insecticide, these compounds in low doses have low toxicity for mammalians, in comparison to other compounds, with insecticide effects. The contact of these compounds in sublethal doses begins in early life and many cases, in intrauterine life. Considerable diseases still with undefined etiology, such as neurodegenerative conditions, and Huntington's Disease (HD) is one of them. HD is related to overexpression of Polyglutamine (PolyQ40), its aggregation, and non-solubilization, which leads to neural, behavioral, and cognitive damage. In our study, we evaluate the effect of two sublethal doses of a prallethrin-based insecticide (P-BI), in three different Caenorhabditis elegans life stages transgenerational, neonatal, and lifespan. We evaluated the Body bends and pharyngeal pumping rate, and social feeding as behavioral biomarkers. As well as acetylcholinesterase activity (AChE), PolyQ40 aggregation, antioxidant enzymes, and heat shock protein (HSP) expression. We observe that the toxic effect of P-BI is more pronounced on transgenerational and lifespan exposure. Both sublethal doses of P-BI decreased the AChE activity and retard the HSP expression as well as increased the PolyQ40 aggregates indicating a clear biomarker for possible effect in the progression of the HD, by the environmental contamination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The endocrine disruptors (ED), even in low concentration, can change the homeostasis of an organism through the biochemical and physiological pathways; and are gaining more relevance due to their well-reported presence in the natural environment. EDs mainly affect non-target animals, which can bioaccumulate, leading to changes in metabolism. Another problem is due to several organisms that compose the aquatic biota serving as a basis of the food chain and transferring it to higher trophic levels. Here we evaluated the dietary transference of 17α-ethinylestradiol (EE2), in adult zebrafish chronically fed by EE2-bioaccumulated brine shrimp (BS). For this, we evaluated behavioral biomarkers such as the novel tank test (NTT), social preference test (SPT), mirror-induced aggressivity (MIA), and biochemical biomarkers such as acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CTL), and glutathione-S-transferase (GST) activity, cortisol, and lipid peroxidation levels in adult zebrafish. The behavioral effects can be explained by the changed effects on acetylcholinesterase activity as well as in the antioxidant system mainly affected by the high levels of EE2 identified by HPLC shown that had occurred during a dietary transfer for fish. EE2 has a potential pattern for bioaccumulation and dietary transfer in biological tissue and EE2 can affect the behavior of fish. The observed effects could be dangerous to the environment, affecting, other animals and even human health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The consumption of progestins has increased considerably in recent decades, as has their disposal into the environment. These substances can negatively affect the reproduction, physiology, and behavior of non-target organisms, such as fish. We aimed to evaluate the effects of exposure to environmentally relevant concentrations of levonorgestrel-control birth based (1.3, 13.3, 133, and 1330 ng/L) on the development and behavior of zebrafish (Danio rerio) in terms of mortality, hatching, spontaneous movement, and larval and adult behavioral tests. Exposure caused anxiogenic-like behavior in larvae, which persisted in adults, as demonstrated by the light-dark test. In contrast, it caused anxiolytic-like behavior in the novel tank test. There was a high mortality rate at all tested concentrations and increases in the hormone cortisol at 13.3 ng/L that affected the sex ratio. These changes may lead to an ecological imbalance, emphasizing the risk of early exposure to progestins in the environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Anthropogenic noises are widespread and affect marine wildlife. Despite the growing knowledge on noise pollution in the marine environment, its effects on fish cognition are scarce. Here, we investigated the effects of sound exposure on anxiety-like behavior and memory retention on dusky damselfish Stegastes fuscus. The animals were trained in a conditioned place aversion task, and exposed to two daily sessions of music at intensities of 60-70 dBA or 90-100 dBA, while the control group was kept at 42-46 dBA (no music) for five days. After that, fish were tested in the novel tank paradigm and tested for the memory of the aversive task. In the novel tank, animals exposed to sound spent more time still and decreased the distance from the bottom of the tank. Animals also spent more time on the aversive side of the conditioning tank. These results suggest that anthropogenic noise applied through high-intensity music can increase anxiety and decrease memory retention in S. fuscus, suggesting the deleterious potential of noise for reef species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Regulation of inflammation is a critical process for maintaining physiological homeostasis. The λ-carrageenan (λ-CGN) is a mucopolysaccharide extracted from the cell wall of red algae ( Chondrus crispus ) capable of inducing acute intestinal inflammation, which is translated into the production of acute phase reactants secreted into the blood circulation. However, the associated mechanisms in vertebrates are not well understood. Here, we investigated the crucial factors behind the inflammatory milieu of λ-CGN-mediated inflammation administered at 0, 1.75, and 3.5% (v/w) by i.p. injection into the peritoneal cavity of adult zebrafish (ZF) ( Danio rerio ). We found that polymorphonuclear leukocytes (neutrophils) and lymphocytes infiltrating the ZF peritoneal cavity had short-term persistence. Nevertheless, they generate a strong pattern of inflammation that affects systemically and is enough to produce edema in the cavity. Consistent with these findings, cell infiltration, which causes notable tissue changes, resulted in the overexpression of several acute inflammatory markers at the protein level. Using reversed-phase high-performance liquid chromatography followed by a hybrid linear ion-trap mass spectrometry shotgun proteomic approach, we identified 2938 plasma proteins among the animals injected with PBS and 3.5% λ-CGN. First, the bioinformatic analysis revealed the composition of the plasma proteome. Interestingly, 72 commonly expressed proteins were recorded among the treated and control groups, but, surprisingly, 2830 novel proteins were differentially expressed exclusively in the λ-CGN-induced group. Furthermore, from the commonly expressed proteins, compared to the control group 62 proteins got a significant ( p < 0.05) upregulation in the λ-CGN-treated group, while the remaining ten proteins were downregulated. Next, we obtained the major protein-protein interaction networks between hub protein clusters in the blood plasma of the λ-CGN induced group. Moreover, to understand the molecular underpinnings of these effects based on the unveiled protein sets, we performed a bioinformatic structural similarity analysis and generated overlapping 3D reconstructions between ZF and humans during acute inflammation. Biological pathway analysis pointed to the activation and abundance of diverse classical immune and acute phase reactants, several catalytic enzymes, and varied proteins supporting the immune response. Together, this information can be used for testing and finding novel pharmacological targets to treat human intestinal inflammatory diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Charlie-Silva, Feitosa, Pontes, Fernandes, Nóbrega, Gomes, Prata, Ferraris, Melo, Conde, Rodrigues, Aracati, Corrêa-Junior, Manrique, Superio, Garcez, Conceição, Yoshimura, Núñez, Eto, Fernandes, Freitas, Ribeiro, Nedoluzhko, Lopes-Ferreira, Borra, Barcellos, Perez, Malafaia, Cunha, Belo and Galindo-Villegas.)

Ilex paraguariensis (Herb mate) is a native plant from South America, widely consumed through the infusion of dried leaves. The presence of antioxidant properties in herb mate may be relevant and contribute to evaluating the effect of its compounds against oxidative stress, which could cause neurodegenerative diseases. Despite having health benefits, there are reports of the presence of heavy metals in extracts obtained from the infusion. One of these metals is iron (Fe), found in large amounts in herb mate. To reverse the cumulative effects of metals and Fe in the body, the use of Deferoxamine (Dfx) is indicated, being a potent chelator of Fe. In this work, we aimed to evaluate the antioxidant potential of the micro-encapsulated extract of I. paraguariensis (MEIP) supplemented with Dfx on zebrafish behavior and biochemical biomarkers. To evaluate the effect per se and the supplementation, four groups were established: the first group was the control (water); the second, fish treated with MEIP; the third group was formed of fish treated with Dfx; while the fourth group was treated with both MEIP and Dfx. When applied alone, Dfx presents an anxiogenic-like pattern on zebrafish ( Danio rerio ), while the MEIP shows an anxiolytic-like behavior. The antioxidant enzymes are re-modulated close to control when the MEIP + Dfx is applied. The cholinergic system shows an activation of the signaling, as well as the heme radical group formation, which is not affected by the Dfx-chelating effect. Thus, the supplementation of MEIP with Dfx is important to transform this extract into one that is safer and healthier for human consumption.

Pesticides reach water bodies through different routes, either owing to incorrect packaging disposal, direct application to control macrophytes, leaching from fields, or natural degradation processes. In the aquatic environment, adverse effects in non-target species that come in contact with these substances are poorly understood. Currently, the most used pesticides are glyphosate (GBH) and 2,4-dichlorophenoxyacetic acid-based herbicides (DBH), as its presence in water bodies is already known, we used environmental concentrations and our exposure time comprised the entire period of organogenesis (3-120 h post-fertilization). We evaluated the response of embryos in their early development with the parameters of mortality, hatching, spontaneous movement, and heart rate; and it's through behavior the open field test and aversive stimulus, as well as biochemical analyzes of acetylcholinesterase activity (AChE), catalase (CTL) and superoxide dismutase (SOD) as a possible mechanism of action. Exposure to GBH decreased survival, caused hypermobility and anxiolytic behavior, negatively affected the anti-predatory behavior of the larvae, and increases acetylcholinesterase activity, whereas exposure to DBH caused only slight hypermobility in the larvae and increases acetylcholinesterase activity. These changes may compromise the perpetuation of the species, the search for partners/food, and facilitate the action of predators, which can result in serious ecological consequences., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The harmful effects of heavy metals on organisms have not been fully described. At present, there is a close relationship between neurodegenerative diseases and copper toxicity. In addition, the copper effect on the central nervous system is followed by high levels of free radicals in different body tissues. An increase in free radical levels leads to aging-related diseases, resulting in the appearance of senile comorbidities. An increase in the consumption of natural compounds that could help to reduce this dangerous effect on organisms was observed. Pitaya (Hylocereus undatus) is a tropical fruit with great antioxidant potential and can help the organism with oxidative damage. This study evaluated the effect of H. undatus on zebrafish organisms in front of copper-induced toxicity. Therefore, the behavior, cholinergic system, antioxidant enzymes, and ALAD activity were evaluated as biomarkers. Our results highlight the great potential of Pitaya's pulp to reduce the levels of anxiety and aggressivity in fish and reduce cortisol levels. It could mediate the normal response of the cholinergic nervous system, antioxidant enzymes, and ALAD activity. Therefore, our data suggest that pitaya might improve the senile aging. PRACTICAL APPLICATIONS: The potential practical application of this study is related to the neuroprotective effect of the Hylocereus undatus microencapsulated pulp extract against metal-induced impairments. The results have shown that this extract is able to reduce the copper-induced damage modulating the antioxidant system and the cholinergic nervous system. One of the implicated potentials of use for this extract is the food supplementation to its fortification., (© 2022 Wiley Periodicals LLC.)

Estrogen is considered to be an endocrine disrupter and is becoming increasingly more prevalent in the daily life of humans. In some cases, estrogen is not fully metabolized by organisms and may be excreted in either its original form or in organic complex forms, into water residue systems reaching concentrations of 0.05 ng.L -1 to 75 ng.L -1 . However, estrogen 17α-ethinylestradiol (EE2), which is used in oral contraceptives, is very difficult to remove from water. Here, we evaluated whether the synthetic hormone, EE2, affects the nervous system and the behavior of adult zebrafish. We established a range of concentrations (0.05, 0.5, 5, 50, and 75 ng.L -1 ), in addition to the control, to evaluate the effect of this compound and its bioaccumulation in zebrafish tissues. Here we show that EE2 bioaccumulates in fish and can change its behavior with an increased time in the upper zone (novel tank test) and far from the shoal segment (social preference test), demonstrating a clear anxiolytic pattern. The anxiolytic effect of EE2 can be harmful as it can affect the stress response of the species. The results presented herein reinforce the idea that the presence of EE2 in environmental water can be dangerous for non-target animals., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The addition of fruit to the diet is very important, and we can use nutraceutical and functional foods for this supplement. A little-known fruit is a red pitaya (Hylocereus undatus) that has been widely reported to have a high antioxidant potential. In this study, we analyzed the in vitro and in vivo antioxidant capacity of microencapsulated pitaya extract on the behavior, antioxidant, and nervous system of the nematode Caenorhabditis elegans. The worms were treated with fruit extract before and after juglone-induced stress, to determine the protective or curative effects of pitaya. We have been evaluated cholinergic, antioxidant, and behavioral biomarkers. We have evidenced that the pulp of pitaya contains antioxidant compounds and can serve as a potential nutraceutical product. In addition, the fruit extract was effective in preventing and/or reverse the stress-induced damages, even at high levels of chemical stress at all evaluated parameters. PRACTICAL APPLICATIONS: The potential applications and uses aimed by this research are related to the supplementation of foods given the antioxidant effect. Our data suggested that the effect of the pitaya fruit microencapsulated pulp extract was effective to prevent and repair the damage caused by oxidative stress. Besides the use of this microencapsulated extract can be an auxiliary in the treatment of diseases related to oxidative damage as well as promoting senescent aging. Another important use is the application of this extract as a dietary supplement to fortify the antioxidant system., (© 2021 Wiley Periodicals LLC.)

Despite the significant increase in the generation of SARS-CoV-2 contaminated domestic and hospital wastewater, little is known about the ecotoxicological effects of the virus or its structural components in freshwater vertebrates. In this context, this study evaluated the deleterious effects caused by SARS-CoV-2 Spike protein on the health of Danio rerio, zebrafish. We demonstrated, for the first time, that zebrafish injected with fragment 16 to 165 (rSpike), which corresponds to the N-terminal portion of the protein, presented mortalities and adverse effects on liver, kidney, ovary and brain tissues. The conserved genetic homology between zebrafish and humans might be one of the reasons for the intense toxic effects followed inflammatory reaction from the immune system of zebrafish to rSpike which provoked damage to organs in a similar pattern as happen in severe cases of COVID-19 in humans, and, resulted in 78,6% of survival rate in female adults during the first seven days. The application of spike protein in zebrafish was highly toxic that is suitable for future studies to gather valuable information about ecotoxicological impacts, as well as vaccine responses and therapeutic approaches in human medicine. Therefore, besides representing an important tool to assess the harmful effects of SARS-CoV-2 in the aquatic environment, we present the zebrafish as an animal model for translational COVID-19 research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Copper (Cu) is an essential metal and it is important for metabolism. However, in high concentrations, it becomes toxic. Metal-induced toxicity is the cause of many neurodegenerative diseases. So it is necessary to search mechanisms to find ways of healthy aging. Natural compounds and diets based on fruits are increasingly common and could lead to a healthy life. Pitaya (Hylocereus undatus) is a tropical and Latin American, fruit that is gaining more popularity due to its antioxidant properties. Here, we evaluate the preventive and curative effect of different doses of microencapsulated pulp H. undatus extract on copper-induced toxicity. For this we use the nematode Caenorhabditis elegans, to investigate the effects of pitaya extract on behavior, lipid peroxidation, antioxidant chaperon, and cholinergic nervous system (ColNS). Results showed behavioral changes, decreased cell death biomarkers, and lipid peroxidation caused by copper, and these toxic effects were prevented and reverted by Pitaya's extract. After all, the extract can be used in diet as a supplement and studied to treat or prevent specific diseases, some of them linked to contamination and senility-related conditions. PRACTICAL APPLICATIONS: This research has been aimed to provide the uses of Hylocereus undatus microencapsulated pulp extract for the prevention and treatment of copper-induced toxicity. We have been shown that Pitaya is a good source of antioxidant compounds that can ameliorate the antioxidant system as well as the cholinergic nervous system avoiding behavior changes before and after the metal toxicity of copper. Therefore, the potential applications and common use of this extract can serve as food supplementation to prevent metal oxidative damage as well as to repair clinical cases of copper poisoning., (© 2022 Wiley Periodicals LLC.)

Genistein is a phytoestrogen, which is structurally similar to 17β-estradiol. It is present in plants, food, and as a contaminant in effluents. In this article, we demonstrate the effects of embryonic exposure to three different concentrations of genistein (10 μg/L, 40 μg/L, and 80 μg/L) which is similar to those found in effluents. Zebrafish eggs were exposed during the first 72 h post-fertilization (hpf). Heart rate was evaluated at 48 hpf and mortality rate was assessed during the first 72 hpf. The light/dark (LDT) and open field (OFT) behavioral tests were applied to the larvae (6 dpf), and the novel tank (NTT), social preference (SPT), light-dark (LDT), and sexing tests were performed on adult fish (90 dpf). Embryonic exposure to genistein caused anxiolytic-like behavior in both larvae and adult animals. In adult stage, we observed an increase in locomotor activity and antisocial behavior in the concentration of 40 μg/L. There was an increase in the mortality rate in all concentrations when compared to the control and an increase in heart rate at the concentration of 80 μg/L. Exposure to 10 μg/L generated a higher frequency of females when compared to the control group. Our results show that exposure to genistein during the embryonic phase brings damage in the short and long term as it increases the mortality rate and leads to behavioral disorders both in the larval stage, with perpetuation until adult stage. The anxiolytic-like effect and less social interaction are effects that harm fish survival., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The zebrafish (Danio rerio) has been considered a suitable model organism to assess the evolutionarily conserved bases of behavioral and neuroendocrine responses to stress. Depending on the nature of the stressor, prolonged stress may elicit habituation or evoke long-term changes in the central nervous systems (CNS) often associated with various neuropsychiatric disorders. Conspecific alarm substance (CAS) and net chasing (NC) constitute chemical and physical stressors, respectively, which cause aversive behaviors and physiological changes in fishes. Here, we investigate whether predictable chronic stress (PCS) using two homotypic stressors differently modulates behavioral and physiological responses in zebrafish. PCS-CAS or PCS-NC were performed for 14 days, 2-times daily, while locomotion, exploratory activity, anxiety-like behaviors, and whole-body cortisol levels were measured on day 15. PCS-CAS reduced distance traveled, the number of transitions and time in top area, as well as increased the latency to enter the top in the novel tank test. In the light/dark test, CAS-exposed fish showed decreased time spent in lit area, shorter latency to enter the dark area, and increased risk assessments. PCS-CAS also increased whole-body cortisol levels in zebrafish. Although PCS-NC reduced the latency to enter the dark area, whole-body cortisol levels did not change. Moreover, acute experiments revealed that both CAS and NC promoted anxiogenesis and increased cortisol levels, suggesting habituation to stress following PCS-NC. Overall, our novel findings demonstrate that PCS induces behavioral and physiological changes in zebrafish depending on the nature of the stressor., (Copyright © 2021. Published by Elsevier Inc.)

The dopaminergic system of zebrafish is complex and the numerous pathways and receptors in the central nervous system (CNS) are being extensively studied. A critical factor for the synthesis, activation and release of catecholamines (CAs) is the presence of tyrosine hydroxylase, an enzyme which converts L-tyrosine into levodopa. Levodopa thus is the intermediary in the synthesis of dopamine (DA) and norepinephrine (NE) and promotes its release; therefore, CAs play an important role in the CNS with hormonal functions. Here, we use levodopa/carbidopa to clarify the involvement of the dopaminergic pathway in the stress response in zebrafish submitted to an acute stress challenge. Acute stress was induced by chasing fish with a net for 2 min and assessed by measuring whole-body cortisol levels. Two experiments were carried out, the first with exposure to levodopa/carbidopa and the second with exposure to AMPT and levodopa/carbidopa. Levodopa/carbidopa balances the stress response through its action on the zebrafish hypothalamic-pituitary-adrenal (HPA) axis. Changes in cortisol levels suggest that DA was related to the balance of the stress response and that NE decreased this response. These effects were specific to stress since levodopa/carbidopa did not induce changes in cortisol in non-stressed fish.

The zebrafish (Danio rerio) is widely used as a promising translational model organism for studying various brain disorders. Zebrafish are also commonly used in behavioral and drug screening assays utilizing individually tested (socially isolated) fish. Various sounds represent important exogenous factors that may affect fish behavior. Mounting evidence shows that musical/auditory environmental enrichment can improve welfare of laboratory animals, including fishes. Here, we show that auditory environmental enrichment mitigates anxiogenic-like effects caused by acute 24-h social isolation in adult zebrafish. Thus, auditory environmental enrichment may offer an inexpensive, feasible and simple tool to improve welfare of zebrafish stocks in laboratory facilities, reduce unwanted procedural stress, lower non-specific behavioral variance and, hence, collectively improve zebrafish data reliability and reproducibility., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Methylphenidate (MPH) is a psychostimulant widely misused to increase wakefulness by drivers and students. Also, MPH can be found in dietary supplements in a clandestine manner aiming to burst performance of physical exercise practitioners. The abusive use of high doses of caffeine (CAF) in these contexts is equally already known. Here, we demonstrate the behavioral, oxidative and mitochondrial effects after acute exposure to high doses of MPH (80 mg/L) and CAF (150 mg/L), alone or associated (80 mg/L + 150 mg/L, respectively). We used zebrafish as animal model due to its high translational relevance. We evaluated the behavioral effects using the Novel Tank Test (NTT), Social Preference Test (SPT) and Y-maze Task and analyzed biomarkers of oxidative stress and activity of mitochondrial respiratory chain complexes. MPH alone induced antisocial behavior. MPH inhibited lipid peroxidation. The association of MPH + CAF presented memory impairment and anxiogenic behavior. In oxidative status, it inhibited lipid peroxidation, increased protein carbonylation and mitochondrial complex II, III and IV activity. Our results demonstrate that MPH and CAF alone negatively impact the typical behavioral of zebrafish. When associated, changes in cognition, memory, oxidative and mitochondrial status are more relevant., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Viticulture plays an important role in generating income for small farms globally. Historically, vineyards use large quantities of phytosanitary products, such as Bordeaux mixture [Ca(OH) 2  + CuSO 4 ], to control plant diseases. These products result in the accumulation of copper (Cu) in the soil and increases the risk of transfer to water bodies. Thus, it is important to evaluate whether the presence of Cu-bearing particles in water is toxic to aquatic fauna. This study conducted chemical, mineralogical, and particle size evaluations on water samples and sediments collected from a watershed predominantly cultivated with old vineyards. The proportion of Cu-rich nanoparticles (<10 nm) in the sediment was ~27%. We exposed zebrafish to different dilutions of water and sediment samples that collected directly from the study site (downstream river) under laboratory conditions. Then, we evaluated their exploratory behavior and the stress-related endocrine parameter, whole-body cortisol. We also carried out two experiments in which zebrafish were exposed to Cu. First, we determined the median lethal concentration (LC 50-96 h ) of Cu and then assessed whether Cu exposure results in effects similar to those associated with exposure to the water and sediment samples collected from the study site. The water and sediment samples directly impacted the exploratory behavior of zebrafish, showing clear anxiety-like behavioral phenotype and stress in terms of cortisol increase (during the second rain event). The Cu exposure did not mimic the same behavioral changes triggered by the water and sediment samples, although it had caused similar stress in the fish. Our results highlight that even at low concentrations, the water and sediment samples from vineyard watershed runoff were able to induce behavioral and endocrine changes that may harm the ecological balance of an aquatic environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

We report the effects of acute and chronic stress on the expression of selective immune-related genes and markers of neuronal function in the brain of the zebrafish ( Danio rerio ). Fish were distributed into three groups: the non-stressed control group; the acute stress (AS) group, submitted to a single stressing episode; and the unpredictable chronic stress (UCS) group, submitted to two daily stressing episodes of alternating times and types of stress. The stressing protocols were applied for a period of 14 days. The UCS protocol triggered the expression of the pro-inflammatory cytokine genes IL-1β and TNF-α, the anti-inflammatory cytokine IL-10 (negative feedback from the immune system), reduction in cFOS gene expression, and caused neuro-inflammation. The AS protocol had no effect on gene expression. Altered expression of cytokine genes, as observed in our study, correlates with several pathologies associated with neuro-inflammation, and the reduction of cFOS gene expression may indicate the occurrence of reduced neuronal plasticity. Our study further extends our knowledge about the interaction of the immune system and the different forms of stress.

Taurine is one of the most abundant amino acids in vertebrates involved in important physiological functions, including osmoregulation, membrane stability, and neuronal activity. The pleiotropic effects of taurine support the existence of different mechanisms of action (e.g., modulation of GABA A , strychnine-sensitive glycine, and NMDA receptors), which can play a role in aggressive-related responses. However, the mechanisms underlying the effects of taurine on aggression are still poorly understood. Because aggression has been associated with diverse central mechanisms, especially serotonergic activity, we aimed to investigate the involvement of this system in taurine-induced aggression in zebrafish. We treated adult zebrafish with ρ-chlorophenylalanine (ρCPA), an inhibitor of the serotonin synthesis, as well as 5-HT 1A receptor antagonist and agonist (WAY100135 and buspirone, respectively). Taurine effects were tested individually at three concentrations (42, 150, and 400 mg/L) for 60 min. We further analyzed the effects on aggression and locomotion using the mirror-induced aggression test. Taurine concentration that changed behavioral responses was selected to the succeeding pharmacological experiments using ρCPA, WAY100135, and buspirone. We found that buspirone did not alter the aggression. Yet, 42 mg/L taurine increased aggression, which was abolished by ρCPA and WAY100135, indicating the involvement of 5-HT 1A receptors in taurine-mediated aggression. These set of data support an indirect mechanism mediating taurine-induced aggression via serotonin release and activation of 5-HT 1A receptors in zebrafish. While the exact mechanisms underlying aggression are still unclear, our novel findings reveal a key role of the serotonergic system in the effects of taurine, supporting the use of zebrafish models to understand the neural basis of aggression in vertebrates., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Residual contamination of water with MPH represents a severe environmental issue because it can affect non-target animals. Here we describe the behavioral effects in zebrafish after chronic contamination of water containing residues of MPH (0.1875, 1.875 and 3 ug/L). These doses are environmentally relevant since they reflect those found in wastewaters. We evaluated the behavioral effect through the novel tank test (NTT) and social preference test (SPT), and after euthanasia we analyzed oxidative stress parameters. Zebrafish exposed to MPH presented a social impairment, avoiding the conspecifics segment in the social preference test. In addition, MPH in the lowest concentration provoked an anxiolytic effect in the novel tank test. Oxidative stress is not related to these changes. Since the maintenance of an intact behavioral repertoire is crucial for species survival and fitness, our results demonstrate that residual contamination of water by MPH can be a threat to zebrafish, impacting directly to its well-being and survival in the aquatic environment., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Due to human activities, there is an increasing presence of agrochemicals residues in water bodies, which could be attributed to an increased use of these chemicals, incorrect disposal of packaging materials, and crop leaching. The effects of these residues on prey-predator relationship of aquatic animals are poorly known. Here, we show that fish acutely exposed to glyphosate, 2,4-D, and methylbenzoate-based agrichemicals have their anti-predatory responses impaired. We exposed zebrafish to sub-lethal concentrations of agrichemicals and evaluated their behavioral reaction against a simulated bird predatory strike. We observed that agrichemical-exposed fish spent more time in a risky area, suggesting that the pesticides interfered with their ability of risk perception. Our results highlight the impairment and environmental consequences of agrochemical residues, which can affect aquatic life and crucial elements for life (food web) such as the prey-predator relationship.

Stress is known to modulate behavioral responses and rapid decision-making processes, especially under challenging contexts which often occur in social and cooperative interactions. Here, we evaluated the effects of acute stress on cooperative behavior of the Indo-Pacific cleaner wrasse (Labroides dimidiatus) and the implications of pre-treatment with monoaminergic compounds: the selective serotonin reuptake inhibitor - fluoxetine, the 5-HT 1A receptor antagonist - WAY-100,635, the D 1 receptor agonist - SKF-38393, and the D 1 receptor antagonist - SCH-23390. We demonstrated that stress decreased the predisposal to interact and increased cortisol levels in cleaners, which are alleviated by fluoxetine and the dopaminergic D 1 antagonist. Overall, our findings highlight the crucial influence of stress on cooperative behavior., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Zebrafish has become an animal model in research and articles have established ideal conditions for their maintenance. However, little is known regarding the influence of gender and other cues on zebrafish behavior. Thus, here we analyzed the exploratory and social behavior of different sexes (male and female, mixed or segregated) under different housing conditions with various types of stimuli (visual or/and chemical cues and structural environmental enrichment). Segregated females and males were more active than mixed individuals and females were more anxious. Fish that visualized and smelled the opposite sex presented higher activity and were less anxious than individuals that only smelled or visualized the opposite sex. Fish segregated by sex while being allowed to visualize and smell the opposite sex with the presence of structural environmental enrichment exhibited lower activity and anxiety-like behavior than fish without structural environmental enrichment. Thus, we emphasized that these variables should be taken into account in housing conditions and should be detailed for better replicability and reproducibility of experiments performed with zebrafish., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The synthetic estrogen, 17-α-ethinylestradiol (EE2), present in contraceptive pills, is an endocrine-disrupting chemical (EDC) that can be found in the aquatic environment. We examined the impacts of EE2 on zebrafish behavioral and physiological responses through the novel tank test (NTT), which measures anxiety-like behavior; the mirror-induced aggression (MIA) test, which measures aggressiveness; and the social preference test (SPT), which measures social cohesion. The steroid hormone levels were also measured. Here, we show that exposure to EE2 impairs stress responses by regulating the levels of specific hormones and eliciting an anxiolytic response, increasing aggression, and reducing social preference in zebrafish. In nature, these changes in behavior compromise reproduction and anti-predator behaviors, which, in turn, affects species survival. The maintenance of an intact behavioral repertoire in zebrafish is essential for their survival. Thus, our results point to the danger of environmental contamination with EE2 as it may alter the dynamics of the prey-predator relationship.

Acute and chronic stressors are common triggers of human mental illnesses. Experimental animal models and their cross-species translation to humans are critical for understanding of the pathogenesis of stress-related psychiatric disorders. Mounting evidence suggests that both pharmacological and non-pharmacological approaches can be efficient in treating these disorders. Here, we analyze human, rodent and zebrafish (Danio rerio) data to compare the impact of non-pharmacological and pharmacological therapies of stress-related psychopathologies. Emphasizing the likely synergism and interplay between pharmacological and environmental factors in mitigating daily stress both clinically and in experimental models, we argue that environmental enrichment emerges as a promising complementary therapy for stress-induced disorders across taxa. We also call for a broader use of novel model organisms, such as zebrafish, to study such treatments and their potential interplay., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Environmental pollution caused by antipsychotic residues is a relevant ecological problem. Studies revealed that residues of these drugs are present in a wide range of different ecosystems and can have adverse effects on non-target organisms even in low environmental concentrations. Among these antipsychotic drugs, aripiprazole (APPZ) is a second-generation atypical antipsychotic that is a partial agonist of dopaminergic and serotoninergic receptors. APPZ is used to treat schizophrenia, bipolar disorder, autism, obsessive-compulsive disorder, and anxiety or panic disorders. Thus, in this study we posed the following question: "What will be the behavioral effects of waterborne APPZ on fish?" To answer this question, we exposed adult zebrafish to different APPZ concentrations (0.556, 5.56, and 556 ng/L) for 15 min and evaluated their exploratory, anxiety-like, social, and anti-predatory behaviors. Our results showed that, despite the apparent beneficial reversal of stress-induced social impairment and anxiety-like behavior, APPZ exposure impaired the anti-predatory reaction of adult zebrafish. Taken altogether, our results show that APPZ-exposed zebrafish may have a decreased perception of predators, even at concentrations lower than those already detected in the environment. A failure to exhibit an antipredatory response may favor the predator, decrease the fitness of the prey species, and, consequently, affect the food chain. Our results highlight the risks and consequences associated with APPZ residues in water, which may affect aquatic life and endanger species that depend on appropriate behavioral responses for survival., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Stressful experiences are related to the triggering of anxiety and mood disorders. Tryptophan (amino acid precursor of serotonin synthesis) emerges as important treatment of these disorders. Here, we evaluate the effects of pre-treatment with tryptophan (300 mg/L) and fluoxetine (50 μg/L) in response to acute stress in zebrafish. Overall, acute stress decreased the distance traveled, entries and time in top of tank, as well as increased the cortisol levels, demonstrating an anxiogenic behavior. Tryptophan and fluoxetine prevented anxiogenic effects. This study showed the importance of tryptophan and fluoxetine in the regulation of stress and anxiety-like behavior in adult zebrafish. Collectively, our data support tryptophan effects on stress responses in zebrafish and reinforce the growing utility of this aquatic model to screen CNS therapies., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Environmental contamination caused by the human occupancy and economic activities that generate a wide range of contaminated effluents that reach natural water resources, is a current reality. Residues of agrichemicals used in plant production were detected in different environments and in different countries. Among these agrochemicals, we studied a glyphosate-based herbicide (GBH), a fipronil-based insecticide (FBI), and their mixtures (GBH + FBI). Zebrafish exposed to 3 and 5 mg/L of GBH spend more time in the top zone and less time in the bottom zone. Fish exposed to 0.009 and 0.018 mg/L of FBI spent less time in the bottom zone, whereas zebrafish exposed to the three GBH + FBI mixtures spend more time in the top zone compared with unexposed control fish. This clear anxiolytic pattern, in an environmental context, can directly impair the ability of fish to avoid or evade predators. We concluded that both glyphosate-based herbicide and fipronil-based insecticide and their mixtures alter zebrafish behavior, which may result in significant repercussions on the maintenance of the species as well as on the food chain and the ecosystem.

Since behavior is the connection between the internal physiological processes of an animal and its interaction with the environment, a complete behavioral repertoire is crucial for fish survival and fitness, at both the individual and population levels. Thus, unintended exposure of non-target organisms to antipsychotic residues in the environment can impact their normal behavior, and some of these behavioral changes can be seen during the entire life of the animal and passed to subsequent generations. Although there are some reports related to transgenerational toxicology, little is known of the long-term consequences of exposure to pharmaceutical compounds such as risperidone. Here, we show that zebrafish exposed to risperidone (RISP) during embryonic and larval stages presented impaired anti-predatory behavior during adulthood, characterizing a persistent effect. We also show that some of these behavioral changes are present in the following generation, characterizing a transgenerational effect. This suggests that even short exposures to environmentally relevant concentrations, at essential stages of development, can persist throughout the whole life of the zebrafish, including its offspring. From an environmental perspective, our results suggested possible risks and long-term consequences associated with drug residues in water, which can affect aquatic life and endanger species that depend on appropriate behavioral responses for survival.

Predators are an important selective pressure for prey, and responses to visual exposure to non-predators and to allopatric and sympatric predators may assist the understanding of how prey animals recognize and distinguish potential threats. Here, we visually exposed predator-naïve Nile tilapia (Oreochromis niloticus) to aquaria with only water (handling-negative control), a non-predator fish (Cyprinus carpio), a South American catfish (Pseudoplatystoma coruscans, allopatric predator), and an African catfish (Clarias gariepinus; sympatric predator). We found that Nile tilapia displayed antipredator responses to both predator catfish but not to non-predator fish or negative control conditions. These antipredator responses, however, were stronger to the sympatric catfish in comparison to the allopatric animal. We concluded that Nile tilapia is able to innately distinguish between a sympatric and an allopatric predator based on visual cues. We assume that the innate recognition of the allopatric predator could be attributed to similarities in the body morphology and movement (key stimuli) of the South American and African catfish. Although this is plausible, the mechanism of the innate allopatric recognition remains unknown and deserves future investigation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The zebrafish (Danio rerio) is used as an emergent model organism to investigate the behavioral and physiological responses to stress. The anxiolytic-like effects of taurine in zebrafish support the existence of different mechanisms of action, which can play a role in preventing stress-related disorders (i.e., modulation of GABA A , strychnine-sensitive glycine, and NMDA receptors, as well as antioxidant properties). Herein, we investigate whether taurine modulates some behavioral and biochemical responses in zebrafish acutely submitted to chemical and mechanical stressors. We pretreated zebrafish for 1 h in beakers at 42, 150, and 400 mg/L taurine. Fish were later acutely exposed to a chemical stressor (conspecific alarm substance) or to a mechanical stressor (net chasing), which elicits escaping responses and aversive behaviors. Locomotion, exploration, and defensive-like behaviors were measured using the novel tank and the light-dark tests. Biochemical (brain oxidative stress-related parameters) and whole-body cortisol levels were also quantified. We showed that taurine prevents anxiety/fear-like behaviors and protein carbonylation and dampens the cortisol response following acute stress in zebrafish. In summary, our results demonstrate a protective role of taurine against stress-induced behavioral and biochemical changes, thereby reinforcing the growing utility of zebrafish models to investigate the neuroprotective actions of taurine in vertebrates., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The production of captive fish is only possible through artificial reproduction, but manipulation is a known stressor stimulus. Thus, the objective of the present study was to evaluate the effects of different eugenol concentrations (0, 30, 40, 50 and 60 mg/L) during reproductive management of Rhamdia quelen. Seventy-five mature male R. quelen were randomly distributed among the five treatments, and blood samples were collected at the time of semen collection to measure plasma cortisol. The following parameters were evaluated in the fresh semen samples: motility, motility duration, concentration and fertilization rate. The following parameters were evaluated in the frozen semen samples: motility, motility duration, morphology, membrane integrity, DNA integrity and mitochondrial functionality. The animals anesthetized with eugenol at concentrations of 40 and 50 mg/L had lower levels of plasma cortisol (88.4 and 83.3 ng/mL, respectively) than the control (147.1 ng/mL). For fresh semen, the control treatment presented the highest rate and time of motility but differed (P < 0.05) only from the animals treated with 60 mg/L eugenol. For the cryopreserved semen the highest rates and motility time were observed in the control treatment and in the animals anesthetized with 40 mg/L eugenol, differing (P < 0.05) from anesthetized animals with 50 and 60 mg/L. Mitochondrial functionality was higher in fish anesthetized with 30 mg/L eugenol differing only for animals anesthetized with 60 mg/L. There was no difference between treatments for sperm concentration and fertilization rate of fresh semen. There were no differences (P > 0.05) between treatments in the parameters of membrane integrity, DNA integrity and% of normal spermatozoa after thawing of the cryopreserved semen samples. The use of 30, 40 and 50 mg/L eugenol maintained the seminal quality of the fresh semen, and the quality of the thawed semen was maintained with 30 and 40 mg/L eugenol. These results show that stress reduction can be reconciled with reproductive management without compromising reproductive performance., (Copyright © 2018 Elsevier Inc. All rights reserved.)

In a previous study we showed a clear relationship between immune system and behavior in zebrafish and we hypothesized that the immune system is capable of inducing behavioral changes. To further investigate this subject and to address our main question, here we induced an inflammatory response in one group of fish by the inoculation of formalin-inactivated Aeromonoas hydrophila bacterin and compared their social and exploratory behavior with control groups. After the behavioral tests, we also analyzed the expression of cytokines genes and markers of neuronal activity in fish brain. In the bacterin-inoculated fish, the locomotor activity, social preference and exploratory behavior towards a new object were reduced compared to the control fish while the expression of proinflammatory cytokines in the brain was upregulated. With this study we demonstrated for the first time that the immune system is capable of causing behavioral changes that are consistent with the sickness behavior observed in mammals., (Copyright © 2018 Elsevier Inc. All rights reserved.)