Biology subjects

Reis, C. G.

Publications and source records attributed to Reis, C. G..

7 recordsLinked to original sources

bioRxiv2025

Linalool and trans-nerolidol prevent pentylenetetrazole-induced seizures in adult zebrafish

BackgroundLinalool (LIN) and trans-nerolidol (NER) are terpene alcohols found in plant-derived essential oils commonly used in traditional systems of medicine. Both compounds have shown antiseizure, sedative, and antioxidant effects in rodent and in vitro models. Due to their structural similarity, a comparative evaluation of their antiseizure profiles is warranted. This study examined the effects of acute LIN and NER exposure in a pentylenetetrazole (PTZ)-induced seizure model in zebrafish (Danio rerio). MethodsA total of 240 adult zebrafish were randomly assigned to the following groups: blank control (dechlorinated water), vehicle control (1% DMSO), positive control (50 {micro}M diazepam, DZP), and three concentrations of LIN or NER (4, 40, 400 {micro}M). Fish were exposed to treatments for 10 minutes, transferred to a washout beaker with dechlorinated water for 5 minutes, and then transferred to PTZ (10 mM) for 20-minute behavioral recording. Seizure activity was scored by blinded observers (BORIS(R)), and locomotion was analyzed with ANY-maze software. ResultsLIN at 400 {micro}M and NER at 40 and 400 {micro}M significantly prolonged latency to clonic- and tonic-like seizures and reduced seizure severity. Notably, 400 {micro}M NER exceeded DZP in effect size, and 40 {micro}M NER also enhanced locomotor activity. ConclusionLIN and NER delayed progression to severe seizure stages and reduced seizure severity, supporting their antiseizure potential. NER consistently outperformed LIN, demonstrating stronger efficacy than DZP at the highest concentration. Consistent with rodent studies, these findings position both as promising leads for drug development.

neuroscience↗

bioRxiv2024

Exposure to epoxiconazole induces hyperlocomotion in adult zebrafish

Global agricultural production is sustained by an elevated use of pesticides. Their application in crops results in environmental contamination, which is demonstrated by widespread detections of these chemicals in aquatic ecosystems. This presence poses a risk to non-target organisms and ecological balance since the effects of potential exposure are misunderstood. Epoxiconazole (EPX) is a widely employed triazole fungicide, which has been frequently reported as a contaminant in superficial waters. However, the behavioral effects of EPX exposure in non-target organisms such as fish remain unexplored. We aimed to investigate the effects of EPX exposure on behavioral and biochemical outcomes, using zebrafish as a model organism. For this purpose, a static system was set with concentrations (24, 144, 240 g/L) based on the fungicide environmental detection. The novel tank test (NTT) was performed after 96 h of exposure. The social preference test (SPT) was executed after 120 h, as well as the biochemical assays. In the NTT, the animals increased distance traveled, crossings, entries in the top area, and mean speed, indicating hyperlocomotion. No significant effects were observed in the SPT and the biochemical analyses. We suggest that the increased locomotion is related to the stimulant properties of EPX. Our results contribute to an in-depth understanding of this fungicide effects in zebrafish, which is essential for environmental contamination monitoring and management.

neuroscience↗

bioRxiv2023

N-acetylcysteine and acetyl-L-carnitine did not prevent acute PTZ-induced seizure in adult and larvae zebrafish

Epilepsy is a prevalent neurological disorder, affecting approximately 1 to 2% of the global population. The hallmark of epilepsy is the occurrence of epileptic seizures, which are characterized by predictable behavioral changes reflecting the underlying neural mechanisms of the disease. Unfortunately, around 30% of patients do not respond to the current available pharmacological treatments. Consequently, it is crucial to explore alternative therapeutic options for managing these seizures. Two potential candidates for attenuating seizures are N-acetylcysteine (NAC) and Acetyl-L-carnitine (ALC), as they have shown promising neuroprotective effects through the modulation of the neurotransmitter glutamate. Therefore, this study aims to assess the effects of varying concentrations (0.1, 1.0, and 10 mg/L) of NAC and ALC on acute PTZ-induced seizures in zebrafish, in both adult and larval stages. The evaluation of behavioral parameters such as seizure intensity and latency to the crisis can provide insights into the efficacy of these substances. However, our results indicate that both drugs at any of the tested concentrations were not able to reduce PTZ-induced epileptic seizures. On the other hand, the administration of diazepam demonstrated a notable reduction in seizure intensity and an increase in latencies to higher scores of epileptic seizures. Consequently, we conclude that, under the conditions employed in this study, NAC and ALC do not exhibit any significant effects on acute seizures in zebrafish.

neuroscience↗

bioRxiv2023

Chemically-induced epileptic seizures in zebrafish: a systematic review

The use of zebrafish as a model organism is gaining evidence in the field of epilepsy as it may help to understand the mechanisms underlying epileptic seizures. As zebrafish assays became popular, the heterogeneity between protocols increased, making it hard to choose a standard protocol to conduct research while also impairing the comparison of results between studies. We conducted a systematic review to comprehensively profile the chemically-induced seizure models in zebrafish. Literature searches were performed in PubMed, Scopus and Web of Science, followed by a two-step screening process based on inclusion/exclusion criteria. Qualitative data were extracted and a sample of 100 studies was randomly selected for risk of bias assessment. Out of the 1058 studies identified after removing duplicates, 201 met the inclusion criteria. We found that the most common chemoconvulsants used in the reviewed studies were pentylenetetrazole (n = 180), kainic acid (n = 11), and pilocarpine (n = 10), which increase seizure severity in a dose-dependent manner. The main outcomes assessed were seizure scores and locomotion. Significant variability between the protocols was observed for administration route, duration of exposure, and dose/concentration. Of the studies subjected to risk of bias assessment, most were rated as low risk of bias for selective reporting (94%), baseline characteristics of the animals (67%), and blinded outcome assessment (54%). Randomization procedures and incomplete data were rated as unclear in 81% and 68% of the studies, respectively. None of the studies reported the sample size calculation. Overall, these findings underscore the need for improved methodological and reporting practices to enhance reproducibility and reliability of zebrafish models for studying epilepsy. Our study offers a comprehensive overview of the current state of chemically-induced seizure models in zebrafish, highlighting the common chemoconvulsants used and the variability in protocol parameters. This may be particularly valuable to researchers interested in understanding the underlying mechanisms of epileptic seizures and screening potential drug candidates in zebrafish models. HIGHLIGHTS- We systematically reviewed the effects of chemically-induced seizures in zebrafish; - PTZ is the most used epileptic seizure inducer in zebrafish; - More than 50% of the studies fail to report data such as outlier exclusion criteria and sample size estimation; - The results showed a need for better standardization of protocols.

neuroscience↗

bioRxiv2023

Neurobehavioral effects of fungicides in zebrafish: a systematic review and meta-analysis

With the aim of yielding high productivity levels, pesticides are widely used in global agriculture. Among them, fungicides are compounds intended to inhibit fungal proliferation in crops and seeds. Their application often leads to environmental contamination, with these chemicals persistently being detected in surface waters. This presence may threaten non-target organisms that dwell in the affected ecosystems, including humans. In toxicologic research, the zebrafish (Danio rerio) is the most used fish species to assess the potential effects of fungicide exposure, generating numerous and sometimes conflicting findings. We conducted a systematic review and meta-analysis aiming to synthesize the neurobehavioral effects of fungicides in zebrafish. The search was performed in three databases (PubMed, Scopus, and Web of Science) and the screening was based on a two-stage process guided by pre-defined inclusion/exclusion criteria. Qualitative and quantitative data, as well as reporting quality, were extracted from the included studies (n = 60). Meta-analyses were performed for the outcomes of distance traveled in larvae and adults, and spontaneous movements in embryos. We found an overall significant effect of fungicide exposure on distance, which was lower in exposed versus control groups (SMD -0.44 [-0.74; -0.13], p = 0.0055). No effect was observed for spontaneous movements. The overall heterogeneity for distance and spontaneous movements was considered high (I2 = 80%) and moderate (I2 = 74%), respectively. This can be explained by substantial methodological variation between protocols, whereas a poor reporting practice hinders the proper critical evaluation of the findings. However, a sensitivity analysis did not indicate any study skewing the meta-analyses. This review demonstrates the need for better-designed and reported experiments in this field. Highlights- We systematically reviewed the behavioral effects of fungicides in zebrafish - Fungicides decrease the distance traveled - Fungicide exposure has no significant effects on spontaneous movements - Moderate to high levels of heterogeneity were found - The results showed a need for better-designed studies with clarity of report

pharmacology and toxicology↗

bioRxiv2021

Micronized curcumin causes hyperlocomotion in zebrafish larvae

Zebrafish larvae have been widely used in neuroscience and drug research and development. In the larval stage, zebrafish present a broad behavioral repertoire and physiological responses similar to adults. Curcumin (CUR), a major component of Curcuma longa L. (Zingiberaceae), has demonstrated the ability to modulate several neurobiological processes relevant to mental disorders in animal models. However, the low bioavailability of this compound can compromise its in vivo biological potential. Interestingly, it has been shown that micronization can increase the biological effects of several compounds. Thus, in this study, we compared the effects of acute exposure for 30 minutes to the following solutions: water (control), 0.1% DMSO (vehicle), 1 M CUR, or 1 M micronized curcumin (MC) in zebrafish larvae 7 days post-fertilization (dpf). We analyzed locomotor activity (open tank test), anxiety (light/dark test), and avoidance behavior (aversive stimulus test). Moreover, we evaluated parameters of oxidative status (thiobarbituric acid reactive substances and non-protein thiols levels). MC increased the total distance traveled and absolute turn angle in the open tank test. There were no significant differences in the other behavioral or neurochemical outcomes. The increase in locomotion induced by MC may be associated with a stimulant effect on the central nervous system, which was evidenced by the micronization process.

neuroscience↗

bioRxiv2020

How do zebrafish respond to MK-801 and amphetamine? Relevance for assessing schizophrenia-relevant endophenotypes in alternative model organisms

Background and PurposeSchizophrenia pathophysiology has been associated with dopaminergic hyperactivity, loss of parvalbumin-positive GABAergic interneurons, NMDA receptor hypofunction, and redox dysregulation. Most behavioral assays and animal models to study this condition were developed in rodents, leaving room for species-specific biases that could be avoided by cross-species approaches. As MK-801 and amphetamine are largely used in mice and rats to mimic schizophrenia features, this study aimed to investigate the effects of these drugs in zebrafish. Experimental ApproachAdult zebrafish were exposed to MK-801 (1, 5, and 10 M) or amphetamine (0.625, 2.5, and 10 mg{middle dot}L-1) and observed in paradigms of locomotor activity and social behavior. Oxidative parameters relevant to schizophrenia were quantified in brain tissue. Key ResultsMK-801 disrupted social interaction, an effect that resembles the negative symptoms of schizophrenia. It also altered locomotion in a context-dependent manner, with hyperactivity when fish were tested in the presence of social cues and hypoactivity when tested alone. On the other hand, exposure to amphetamine was devoid of effects on locomotion and social behavior, while increased lipid peroxidation in the brain. Conclusion and ImplicationsKey outcomes induced by MK-801 in rodents were replicated in zebrafish, which suggests this species is suitable as an alternative model animal to study psychotic disorders. More studies are necessary to further develop preclinical paradigms with this species and ultimately optimize the screening of potential novel treatments.

neuroscience↗