In vitro effects of antiepileptic drugs on acetylcholinesterase and ectonucleotidase activities in zebrafish (Danio rerio) brain

Neurotoxic effects of carbamazepine on the mosquitofish Gambusia affinis

In recent years, the presence of pharmaceuticals in the aquatic environment has gained a significant attention. Carbamazepine, a commonly prescribed antiepileptic drug, has been consistently found in aquatic environments at concentrations ranging from nanograms to micrograms, raising concerns about its potential negative impacts on aquatic organisms. The study examined the acute and chronic neurotoxic effects of environmentally relevant and sublethal concentrations of carbamazepine in the mosquitofish Gambusia affinis. After a 96-hour exposure period, the median lethal concentration (LC50) of carbamazepine for G. affinis was determined as 24 mg L - 1. For the current study, sublethal concentrations i.e., one-tenth (2.4 mg L - 1) and one-fifth (4.8 mg L - 1) of the LC50 value were chosen for assessing the neurotoxic effects along with the environmentally relevant concentration (13 ng L - 1). The research findings indicated that carbamazepine had a disruptive impact on the typical growth and behavior of the fish. During the acute exposure phase, physical deformities were observed in the fish, resulting in neonatal and postneonatal fatalities. Furthermore, the neurotoxic effects of carbamazepine were clearly demonstrated through alterations in various neurological parameters, including acetylcholinesterase, dopamine, gamma-aminobutyric acid, serotonin, monoamine oxidase, 5-hydroxyindole acetic acid, adrenaline, and nor-adrenaline. These findings raise concerns about the survival of fish populations in their natural environment.

Multilevel assessment of carbamazepine effects: An integrative approach using zebrafish early-life stages

Carbamazepine (CBZ) is the most commonly used drug in epilepsy treatment, and its metabolites are commonly detected among persistent pharmaceuticals in the aquatic environment. This study aimed to investigate CBZ effects on early-life-stage zebrafish (Danio rerio) (from 2 to 168 hpf) by employing of an integrative approach linking endpoints from molecular to individual level: (i) development; (ii) locomotor activity; (iii) biochemical markers (lactate dehydrogenase, glutathione-S-transferase, acetylcholinesterase and catalase) and (iv) transcriptome analysis using microarray. A 168 h - LC50 of 73.4 mg L-1 and a 72 h - EC50 of 66.8 mg L-1 for hatching were calculated while developmental effects (oedemas and tail deformities) were observed at CBZ concentrations above 37.3 mg L-1. At the biochemical level, AChE activity proved to be the most sensitive parameter, as evidenced by its decrease across all concentrations tested (∼25% maximum reduction, LOEC (lowest observed effect concentration) < 0.6 μg L-1). Locomotor behaviour seemed to be depressed by CBZ although this effect was only evident at the highest concentration tested (50 mg L-1). Molecular analysis revealed a dose-dependent effect of CBZ on gene expression. Although only 25 genes were deregulated in organisms exposed to CBZ when compared to controls, both 0.6 and 2812 μg L-1 treatments impaired gene expression related to development (e.g. crygmxl1, org, klf2a, otos, stx16 and tob2) and the nervous system (e.g. Rtn3, Gdf10, Rtn3), while activated genes were associated with behavioural response (e.g. prlbr and taar). Altogether, our results indicate that environmentally relevant CBZ concentrations might affect biochemical and genetic traits of fish. Thus, the environmental risk of CBZ cannot be neglected, especially in a realistic scenario of constant input of domestic effluents into aquatic systems.

Mixtures of environmental pharmaceuticals in marine organisms: Mechanistic evidence of carbamazepine and valsartan effects on Mytilus galloprovincialis

Unravelling the adverse outcomes of pharmaceuticals mixture represents a research priority to characterize the risk for marine ecosystems. The present study investigated, for the first time, the interactions between two of the most largely detected pharmaceuticals in marine species: carbamazepine (CBZ) and valsartan (VAL), elucidating mechanisms that can modulate bioaccumulation, excretion and the onset of toxicity. Mytilus galloprovincialis were exposed to environmental levels of CBZ and VAL dosed alone or in combination: measurement of drug bioaccumulation was integrated with changes in the whole transcriptome and responsiveness of various biochemical and cellular biomarkers. Interactive and competing mechanisms between tested drugs were revealed by the much higher CBZ accumulation in mussels exposed to this compound alone, while an opposite trend was observed for VAL. A complex network of responses was observed as variations of gene expression, functional effects on neurotransmission, cell cycle, immune responses and redox homeostasis. The elaboration of results through a quantitative Weight of Evidence model summarized a greater biological reactivity of CBZ compared to VAL and antagonistic interactions between these compounds, resulting in a reduced effect of the antiepileptic when combined with valsartan. Overall, new perspectives are highlighted for a more comprehensive risk assessment of environmental mixtures of pharmaceuticals.

Multi-biomarker approach to evaluate the neurotoxic effects of environmentally relevant concentrations of phenytoin on adult zebrafish Danio rerio

Several studies have reported the presence of phenytoin (PHE) in wastewater treatment plant effluents, hospital effluents, surface water, and even drinking water. However, published studies on the toxic effects of PHE at environmentally relevant concentrations in aquatic organisms are scarce. The present study aimed to determine the effect of three environmentally relevant concentrations of PHE (25, 282, and 1500 ng L^-1) on behavioral parameters using the novel tank test. Moreover, we also aimed to determine whether or not these concentrations of PHE may impair acetylcholinesterase (AChE) activity and oxidative status in the brain of Danio rerio adults. Behavioral responses suggested an anxiolytic effect in PHE-exposed organisms, mainly observed in organisms exposed to 1500 ng L^-1, with a significant decrease in fish mobility and a significant increase in activity at the top of the tank. Besides the behavioral impairment, PHE-exposed fish also showed a significant increase in the levels of lipid peroxidation, hydroperoxides, and protein carbonyl content compared to the control group. Moreover, a significant increase in brain AChE levels was observed in fish exposed to 282 and 1500 ng L^-1. The results obtained in the present study show that PHE triggers a harmful response in the brain of fish, which in turn generates fish have an anxiety-like behavior.

The Biological Effects of Pharmaceuticals in the Marine Environment

Environmental pharmaceuticals represent a threat of emerging concern for marine ecosystems. Widely distributed and bioaccumulated, these contaminants could provoke adverse effects on aquatic organisms through modes of action like those reported for target species. In contrast to pharmacological uses, organisms in field conditions are exposed to complex mixtures of compounds with similar, different, or even opposing therapeutic effects. This review summarizes current knowledge of the main cellular pathways modulated by the most common classes of environmental pharmaceuticals occurring in marine ecosystems and accumulated by nontarget species-including nonsteroidal anti-inflammatory drugs, psychiatric drugs, cardiovascular and lipid regulator agents, steroidal hormones, and antibiotics-and describes an intricate network of possible interactions with both synergistic and antagonistic effects on the same cellular targets and metabolic pathways. This complexity reveals the intrinsic limits of the single-chemical approach to predict the long-term consequences and future impact of pharmaceuticals at organismal, population, and community levels.

Human Drug Pollution in the Aquatic System: The Biochemical Responses of Danio rerio Adults

Simple Summary

The release of medicinal products for human use in the aquatic environment is now a serious problem, and can be fatal for the organisms that live there. Danio rerio is a freshwater fish that provides the possibility to study the effects of these pollutants on the health of aquatic organisms. The results of the various existing scientific studies are scarce and conflicting. Here, we review the scientific studies that have analyzed these effects, highlighting that the impacts of drugs are evident in the biochemical responses of these animals.

Abstract

To date, drug pollution in aquatic systems is an urgent issue, and Danio rerio is a model organism to study the toxicological effects of environmental pollutants. The scientific literature has analyzed the effect of human drug pollution on the biochemical responses in the tissues of D. rerio adults. However, the information is still scarce and conflicting, making it difficult to understand its real impact. The scientific studies are not consistent with each other and, until now, no one has grouped their results to create a baseline of knowledge of the possible impacts. In this review, the analysis of literature data highlights that the effects of drugs on adult zebrafishes depend on various factors, such as the tissue analyzed, the drug concentration and the sex of the individuals. Furthermore, the most influenced biochemical responses concern enzymes (e.g., antioxidants and hydrolase enzymes) and total protein and hormonal levels. Pinpointing the situation to date would improve the understanding of the chronic effects of human drug pollution, helping both to reduce it in the aquatic systems and then to draw up regulations to control this type of pollution.

Pharmaceutical Products and Pesticides Toxicity Associated with Microplastics (Polyvinyl Chloride) in Artemia salina

Pharmaceutical products, as well as insecticides and antimicrobials, have been extensively studied, but knowledge of their effects-especially those caused by their mixtures with microplastics-on aquatic organisms remains limited. However, it should be borne in mind that the state of knowledge on acute and chronic effects in aquatic organisms for pharmaceuticals and pesticides is not similar. In response, this investigation analyzed the presence of microplastics (polyvinyl chloride) and their impacts on the toxicity of chlorpyrifos (an insecticide) and triclosan (an antibacterial) when they coincide in the environment, alongside the two most consumed drugs of their type (hypolipemic and anticonvulsant, respectively), namely simvastatin and carbamazepine, in Artemia salina. LC₅₀ and cholinesterase enzyme activity were calculated to determine the possible neurotoxicity associated with emergent contaminants in the treatments. The LC₅₀ values obtained were 0.006 mg/dm³ for chlorpyrifos, 0.012 mg/dm³ for chlorpyrifos associated with microplastics, 4.979 mg/dm³ for triclosan, 4.957 mg/dm³ for triclosan associated with microplastics, 9.35 mg/dm³ for simvastatin, 10.29 mg/dm³ for simvastatin associated with microplastics, 43.25 mg/dm³ for carbamazepine and 46.50 mg/dm³ for carbamazepine associated with microplastics in acute exposure. These results indicate that the presence of microplastics in the medium reduces toxicity, considering the LC₅₀ values. However, exposure to chlorpyrifos and carbamazepine, both alone and associated with microplastics, showed a decline in cholinesterase activity, confirming their neurotoxic effect. Nevertheless, no significant differences were observed with the biomarker cholinesterase between the toxicant and the toxicant with microplastics.

Environmental pharmaceuticals and climate change: The case study of carbamazepine in M. galloprovincialis under ocean acidification scenario

Contaminants of emerging concern and ocean changes are key environmental stressors for marine species with possibly synergistic, but still unexplored, deleterious effects. In the present study the influence of a simulated ocean acidification scenario (pH = 7.6) was investigated on metabolism and sub-lethal effects of carbamazepine, CBZ (1 µg/L), chosen as one of the most widely diffused pharmaceuticals in marine organisms. A multidisciplinary approach was applied on mussels, M. galloprovincialis, integrating measurement of drug bioaccumulation with changes in the whole transcriptome, responsiveness of various biochemical and cellular biomarkers including immunological parameters, lipid and oxidative metabolism, onset of genotoxic effects. Chemical analyses revealed a limited influence of hypercapnia on accumulation and excretion of CBZ, while a complex network of biological responses was observed in gene expression profile and functional changes at cellular level. The modulation of gamma-aminobutyric acid (GABA) pathway suggested similarities with the Mechanism of Action known for vertebrates: immune responses, cellular homeostasis and oxidative system represented the processes targeted by combined stressors. The overall elaboration of results through a quantitative Weight of Evidence model, revealed clearly increased cellular hazard due to interactions of CBZ with acidification compared to single stressors.

Zebrafish models: Gaining insight into purinergic signaling and neurological disorders

Zebrafish (Danio rerio) has been considered a complementary model for biomedical studies, especially due to advantages such as external and rapid development, and genetic manipulation. There is growing interest in this model in neuroscience research since the species has morphological and physiological similarities to mammals and a complex behavioral repertoire. The purinergic signaling has been described in zebrafish, and purinoceptors and nucleotide- and nucleoside-metabolizing enzymes have already been identified in the central nervous system (CNS) of this species. The involvement of the purinergic system in several models of neurological disorders, such as Alzheimers disease, Parkinson's disease, epilepsy, schizophrenia, and autism has been investigated in zebrafish. This mini review presents several studies describing purinergic signaling in the zebrafish CNS and the action of this neurotransmitter system in models of neurological disorders using this species as a biological model. The use of pharmacological approaches at different stages of development may be a useful tool for preclinical assays and the testing of purinergic compounds as new alternatives for the treatment of neurological disorders.

A transcriptomics-based analysis of the toxicity mechanisms of gabapentin to zebrafish embryos at realistic environmental concentrations

Gabapentin (GPT) has become an emerging contaminant in aquatic environments due to its wide application in medical treatment all over the world. In this study, embryos of zebrafish were exposed to gabapentin at realistically environmental concentrations, 0.1 μg/L and 10 μg/L, so as to evaluate the ecotoxicity of this emergent contaminant. The transcriptomics profiling of deep sequencing was employed to illustrate the mechanisms. The zebrafish (Danio rerio) embryo were exposed to GPT from 12 hpf to 96 hpf resulting in 136 and 750 genes differentially expressed, respectively. The results of gene ontology (GO) analysis and the Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis illustrated that a large amount of differentially expressed genes (DEGs) were involved in the antioxidant system, the immune system and the nervous system. RT-qPCR was applied to validate the results of RNA-seq, which provided direct evidence that the selected genes involved in those systems mentioned above were all down-regulated. Acetylcholinesterase (AChE), lysozyme (LZM) and the content of C-reactive protein (CRP) were decreased at the end of exposure, which is consistent with the transcriptomics results. The overall results of this study demonstrate that GPT simultaneously affects various vital functionalities of zebrafish at early developmental stage, even at environmentally relevant concentrations.

Assessing the ecological status of fluvial ecosystems employing a macroinvertebrate multi-taxon and multi-biomarker approach

Biomarkers are recognised sensitive early-warning tools of biological effects in aquatic organisms. In this scope, the main aim of this study was to investigate the potential usefulness of a battery of biomarkers, evaluated in different benthic macroinvertebrate taxa, to discriminate aquatic ecosystems with different levels of ecological status and to provide further clues supporting environmental management. The study took place during the autumn of 2013 and the spring and summer of 2014, and the study cases were two Mediterranean rivers (Âncora and Ferreira rivers), differing in their ecological status. The biomarkers determined are widely employed and comprise a large set of biochemical responses: the activity of enzymes (cholinesterases, glutathione S-transferases, catalase and lactate dehydrogenase) and the levels of lipid peroxidation. They were assessed seasonally and in different macroinvertebrate taxa. Thirteen water physico-chemical parameters were also seasonally determined, and the concentration of seven organophosphorus pesticides and the percentage of 32 trace metals in sediments were determined in the spring. This is particularly useful for water management. Based on this, authorities can take actions to prevent further damage in the ecological status. Multivariate analyses showed distinct patterns of biological response for the Calopteryx spp., Chironomidae and Baetis spp. taxa. Calopteryx spp. and Chironomidae, in particular, showed distinct response patterns for the two rivers, which were fairly stable across seasons. This study sets the foundations for future cost-effective biomonitoring campaigns in Mediterranean rivers, allowing to establish historical data important to understand ecosystem evolution, as well as baseline levels of diagnostic biomarkers in informative macroinvertebrate taxa.

Effects of low concentrations of psychiatric drugs (carbamazepine and fluoxetine) on the freshwater planarian, Schmidtea mediterranea

There is increasing knowledge about the presence of psychiatric pharmaceutical substances in the aquatic environment due to increasing number of ecotoxicological studies with sensitive species in addition to improved methods of analysis. Here, we assessed the effects of two psychiatric substances carbamazepine and fluoxetine in the planarian Schmidtea mediterranea using endpoints such as survival, behaviour (feeding, locomotion), DNA damage and regeneration. Also, planarian asexual reproduction by fissioning was used to assess the reproductive effects of these compounds. Whereas for survival, no effect was observed for carbamazepine exposure, fluoxetine exposure was toxic to planarians with an LC₅₀ of 357.93 and 160.01 μg L^-1 at 48 and 96 h, respectively. Time for head regeneration in decapitated planarians was not affected by either fluoxetine or carbamazepine exposures. Fluoxetine was more toxic than carbamazepine and caused concentration dependent increase in locomotor activity and DNA damage (LOEC's of 0.1-1.0 μg L^-1), and decrease in feeding and fissioning. Despite some alteration on planarian locomotion observed under exposure to intermediate concentrations, no significant effects were observed in the other endpoints in response to carbamazepine. The observations in the present study showed that freshwater planarians such as Schmidtea mediterranea, animal models in neuropharmacology, are sensitive to low concentrations of psychiatric drugs, displaying an array of sensitive sub-lethal endpoints that can be used for the ecological risk assessment of psychiatric substances. Future studies to determine effects of these psychiatric drugs on the levels of neurotransmitters and other biochemical biomarkers in planarians are recommended.

Sociodemographic, Electrophysiological, and Biochemical Profiles in Children with Attention Deficit Hyperactivity Disorder and/or Epilepsy

Attention deficit hyperactivity disorder (ADHD) is among the most prevalent neurobehavioral disorders affecting children worldwide. The prevalence of ADHD is higher in children with epilepsy. Despite the plethora of conducted work, the precise cause of ADHD is not identified yet. We studied here the sociodemographic, clinical, electrophysiological, and biochemical profiles of children with ADHD, epilepsy, and ADHD with epilepsy. Subjects were divided into 4 groups (25 child/group): I—control, II—ADHD, III—epilepsy, and IV—ADHD with epilepsy. Male to female ratio was significantly (p < 0.05) higher in the ADHD (3.1) and ADHD with epilepsy (2.1) groups when compared to the control (1.08) or epilepsy (1.08) groups. Positive family history was significantly evident in patients with epilepsy and ADHD with epilepsy, but not in the control or ADHD groups. Speech development was significantly delayed in the ADHD and ADHD with epilepsy groups. EEG abnormalities were detected in patients with ADHD (12%) and ADHD with epilepsy (68%). Focal frontal activities were significantly detectable in the ADHD (100%) and ADHD with epilepsy (77.8%) groups, whereas focal temporal activity was significantly present in the epilepsy (83.3%) group. Serum ferritin was significantly lower in the ADHD group (110.27 ± 6.64 ηg/ml) when compared to the control (134.23 ± 14.82 ηg/ml), epilepsy (159.66 ± 33.17 ηg/ml), and ADHD with epilepsy (203.04 ± 50.64 ηg/ml) groups. Serum zinc was significantly higher in the ADHD, epilepsy, and ADHD with epilepsy groups (236.63 ± 20.89, 286.74 ± 43.84, and 229.95 ± 67.34 μg/dl, respectively), when compared to the control group (144.21 ± 17.40 μg/dl). Serum adenosine deaminase was insignificantly different among the groups. Our results indicate that gender and family history are significant moderators in the aetiology of ADHD and epilepsy or their comorbidity. We also demonstrated that EEG could be central in the assessment of ADHD with epilepsy cases. Serum ferritin and zinc alteration may contribute significantly in ADHD and epilepsy pathophysiology.

Toxicological profile and acetylcholinesterase inhibitory potential of Palicourea deflexa, a source of β-carboline alkaloids

Palicourea genus is chemically and taxonomically close to Psychotria genus, a well-known source of neuroactive alkaloids. It has been previously reported the pharmacological potential of these alkaloids in some targets related to the neurodegenerative process. In this context, this study was carried out in order to evaluate the toxic effects and acetylcholinesterase (AChE) inhibitory potential of Palicourea deflexa fraction of total alkaloids (FTA). P. deflexa FTA was analyzed by means of HPLC-DAD and HRMS-ESI. We performed toxicological screening through Fish Embryo Toxicity (FET) test using zebrafish embryo and abnormal developmental phenotypes were recorded daily. For AChE inhibition, zebrafish brains were used as enzymatic source and formation of thiolate dianion of 5,5'-Dithiobis(2-nitrobenzoic acid) (DTNB) was used to monitor acetylthiocholine hydrolysis. Lineaweaver-Burk double reciprocal plots were used to indicate mode of inhibition. Chemical analysis of the P. deflexa FTA allowed the identification of the main compound as harman-3-carboxylic acid. This fraction was evaluated in vivo for its toxicological effect. The zebrafish embryo test indicated that the FTA has a lethal concentration of 50% (LC₅₀)=72.18μg/mL. Further, the FTA was evaluated for its AChE inhibitory profile, demonstrating an inhibitory concentration of 50% (IC₅₀) of 50.65μg/mL. Lineaweaver-Burk double reciprocal plots indicated a mixed mode of inhibition. It is reported for the first time the toxicological and pharmacological profile of the alkaloid fraction of Palicourea deflexa in zebrafish models.

Lower vertebrate and invertebrate models of Alzheimer's disease - A review

Alzheimer's disease is a common neurodegenerative disorder which is characterized by the presence of beta- amyloid protein and neurofibrillary tangles (NFTs) in the brain. Till now, various higher vertebrate models have been in use to study the pathophysiology of this disease. But, these models possess some limitations like ethical restrictions, high cost, difficult maintenance of large quantity and lesser reproducibility. Besides, various lower chordate animals like Danio rerio, Drosophila melanogaster, Caenorhabditis elegans and Ciona intestinalis have been proved to be an important model for the in vivo determination of targets of drugs with least limitations. In this article, we reviewed different studies conducted on theses models for the better understanding of the pathophysiology of AD and their subsequent application as a potential tool in the preclinical evaluation of new drugs.

Effects of emerging contaminants on neurotransmission and biotransformation in marine organisms - An in vitro approach

The effects of gold (ionic form and nanoparticles - AuNPs) and pharmaceuticals (carbamazepine and fluoxetine) on enzymes involved in neurotransmission (acetylcholinesterase - AChE) and biotransformation (glutathione S-transferases - GST) were assessed by their incubation with Mytilus galloprovincialis' hemolymph and subcellular fraction of gills, respectively. AuNPs did not alter enzymatic activities unlike ionic gold that inhibited AChE and GST activities at 2.5 and 0.42mg·L(-1), respectively. Carbamazepine inhibited AChE activity at 500mg·L(-1) and fluoxetine at 1000mg·L(-1). GST was inhibited by carbamazepine at 250mg·L(-1) and by fluoxetine at 125mg·L(-1). Increased AChE activity was found in simultaneous exposures to fluoxetine and bovine serum albumin coated AuNPs (BSA-AuNPs). Concerning GST, in the simultaneous exposures, AuNPs revealed protective effects against carbamazepine (citrate and polyvinylpyrrolidone coated) and fluoxetine (citrate and BSA coated) induced inhibition. However, BSA-AuNPs increased the inhibition caused by carbamazepine. AuNPs demonstrated ability to interfere with other chemicals toxicity justifying further studies.

Effects of short-term exposure to fluoxetine and carbamazepine to the collembolan Folsomia candida

Pharmaceuticals, emerging environmental contaminants, have their ecotoxicological effects to non-target organisms in soil largely unknown. This study assessed short-term effects of two human pharmaceuticals, carbamazepine and fluoxetine, to Folsomia candida. Avoidance to spiked soils was assessed after 48 and 96 h exposure and biochemical changes (acetylcholinesterase and glutathione S-transferase activities, and lipid peroxidation levels) after 96 h. F. candida avoided soils spiked with 0.04, 0.4 and 4 mg carbamazepine kg(-1) after 48 h. However, higher number of organisms were found in soils with 40 mg carbamazepine kg(-1), a behavior also displayed for 40 mg fluoxetine kg(-1) spiked soils. After 96 h, F. candida showed avoidance behavior to soils with 4 and 40 mg carbamazepine kg(-1). Acetylcholinesterase activity decreased in 0.4 mg fluoxetine kg(-1) exposed organisms. Peroxidative damages were detected in organisms exposed to 4 and 40 mg kg(-1) carbamazepine and glutathione S-transferase inhibition was observed at 40 mg kg(-1). Data suggests that carbamazepine and fluoxetine may pose risk to soil collembolan.

Changes in the anti-oxidant system in adult epilepsy patients receiving anti-epileptic drugs

Anti-epileptic drugs (AEDs) have been widely used in patients with epilepsy. This study evaluated the adverse effects of two commonly prescribed AED monotherapies, carbamazepine (CBZ) and valproic acid (VPA). The aim of this study was to evaluate the influence of these anti-epileptic drugs on paraoxonase-1 (PON-1), glutathione S-transferase (GST) and acetyl cholinesterase (AChE) activities in the serum of adult patients with epilepsy. Of the 56 epileptic adults, 28 were given valproate, and the remaining 28 were given carbamazepine. Glutathione (GSH) levels in epilepsy patients receiving anti-epileptic drug treatment were insignificantly higher compared with controls. GST activity in epilepsy patients receiving anti-epileptic drug treatment was insignificantly lower compared with controls. PON1 and AChE activity in epilepsy patients receiving anti-epileptic drug treatment was significantly lower compared with controls. PON1 and AChE activities in the serum of patients treated with carbamazepine monotherapy were lower than in patients treated with valproic acid monotherapy.

Carbamazepine attenuates inducible nitric oxide synthase expression through Akt inhibition in activated microglial cells

Abstract Background: Carbamazepine, which was developed primarily for the treatment of epilepsy, is now also useful for the treatment of non-epileptic disorders and inflammatory hyperalgesia. However, the mechanism of its anti-neuroinflammatory action remains poorly understood.

OBJECTIVE

This study elucidates the anti-neuroinflammatory capacity of carbamazepine on microglial activation and the relative mechanisms involved.

MATERIALS AND METHODS

The microglial BV-2 cells were pretreated with carbamazepine for 15 min before activation by lipopolysaccharide (LPS). After LPS stimulation, the expression of inducible nitric oxide synthase (iNOS) was analyzed by Western blotting (WB) and reverse transcription-polymerase chain reaction. Signaling proteins and cyclooxygenase (COX)-2 were also evaluated by WB. The levels of nitrate and tumor necrosis factor (TNF)-α were analyzed by the Griess method and enzyme-linked immunosorbant assay, respectively. The formation of intracellular reactive oxygen species (ROS) was examined by fluorescent analysis.

RESULTS

Carbamazepine strongly attenuated LPS-induced production of NO and iNOS protein at concentrations of 5, 10, and 20 μM. Consistently, it could markedly suppress iNOS mRNA expression stimulated by LPS. Among the signaling pathways, LPS-mediated IκBα degradation or JNK MAPK phosphorylation was not affected by carbamazepine. Interestingly, it was found that carbamazepine could concentration-dependently inhibit LPS-activated phospho-Akt expression. Nevertheless, LPS-induced ROS production was not affected by carbamazepine. Carbamazepine (20 μM) affected either COX-2 expression or TNF-α production induced by LPS with approximately 70% and 51% inhibition, respectively.

DISCUSSION AND CONCLUSION

Our findings showed that carbamazepine exerted selective inhibition on LPS-induced microglial iNOS expression through the down-regulation of Akt activation, and thus may play a pivotal role of anti-neuroinflammation in its therapeutic efficacy.

Cholinesterase activity in the caddisfly Sericostoma vittatum: Biochemical enzyme characterization and in vitro effects of insecticides and psychiatric drugs

Sericostoma vittatum is a caddisfly species, endemic to the Iberian Peninsula, proposed as a biomonitor species for lotic ecosystems. Since inhibition of cholinesterases׳ (ChE) activity has been used to evaluate the exposure of macroinvertebrates to organophosphates and carbamate pesticides, this work intended to characterize the ChE present in this species so their activity can be used as a potential biomarker of exposure. Biochemical and pharmacological properties of ChE were characterized in this caddisfly species using different substrates (acetylthiocholine iodide, propionylthiocholine iodide, and butyrylthiocholine iodide) and selective inhibitors (eserine sulfate, BW284c51, and iso-OMPA). Also, the in vitro effects of two insecticides (carbaryl and chlorantraniliprole) and two psychiatric drugs (fluoxetine and carbamazepine) on ChE activity were investigated. The results suggest that S. vittatum possess mainly AChE able to hydrolyze both substrates acetylthiocholine and propionylthiocholine since: (1) it hydrolyzes the substrate acetylthiocholine and propionylcholine at similar rates and butyrylthiocholine at a much lower rate; (2) it is highly sensitive to eserine sulfate and BW284c51, but not to iso-OMPA; and (3) its activity is inhibited by excess of substrate, a characteristic of typical AChE. in vitro inhibitions were observed only for carbaryl exposure while exposure to chlorantraniliprole and to relevant environmental concentrations of psychiatric drugs did not cause any significant effect on AChE activity. This study suggests that AChE activity in caddisflies can indeed be used to discriminate the effects of specific insecticides in monitoring programs. The use of non-target species such as caddisflies in ecotoxicological research in lotic ecosystems is also discussed.

Intraperitoneal exposure to nano/microparticles of fullerene (C₆₀) increases acetylcholinesterase activity and lipid peroxidation in adult zebrafish (Danio rerio) brain

Even though technologies involving nano/microparticles have great potential, it is crucial to determine possible toxicity of these technological products before extensive use. Fullerenes C₆₀ are nanomaterials with unique physicochemical and biological properties that are important for the development of many technological applications. The aim of this study was to evaluate the consequences of nonphotoexcited fullerene C₆₀ exposure in brain acetylcholinesterase expression and activity, antioxidant responses, and oxidative damage using adult zebrafish as an animal model. None of the doses tested (7.5, 15, and 30 mg/kg) altered AChE activity, antioxidant responses, and oxidative damage when zebrafish were exposed to nonphotoexcited C₆₀ nano/microparticles during 6 and 12 hours. However, adult zebrafish exposed to the 30 mg/kg dose for 24 hours have shown enhanced AChE activity and augmented lipid peroxidation (TBARS assays) in brain. In addition, the up-regulation of brain AChE activity was neither related to the transcriptional control (RT-qPCR analysis) nor to the direct action of nonphotoexcited C₆₀ nano/microparticles on the protein (in vitro results) but probably involved a posttranscriptional or posttranslational modulation of this enzymatic activity. Taken together these findings provided further evidence of toxic effects on brain after C₆₀ exposure.

From omics to drug metabolism and high content screen of natural product in zebrafish: a new model for discovery of neuroactive compound

The zebrafish (Danio rerio) has recently become a common model in the fields of genetics, environmental science, toxicology, and especially drug screening. Zebrafish has emerged as a biomedically relevant model for in vivo high content drug screening and the simultaneous determination of multiple efficacy parameters, including behaviour, selectivity, and toxicity in the content of the whole organism. A zebrafish behavioural assay has been demonstrated as a novel, rapid, and high-throughput approach to the discovery of neuroactive, psychoactive, and memory-modulating compounds. Recent studies found a functional similarity of drug metabolism systems in zebrafish and mammals, providing a clue with why some compounds are active in zebrafish in vivo but not in vitro, as well as providing grounds for the rationales supporting the use of a zebrafish screen to identify prodrugs. Here, we discuss the advantages of the zebrafish model for evaluating drug metabolism and the mode of pharmacological action with the emerging omics approaches. Why this model is suitable for identifying lead compounds from natural products for therapy of disorders with multifactorial etiopathogenesis and imbalance of angiogenesis, such as Parkinson's disease, epilepsy, cardiotoxicity, cerebral hemorrhage, dyslipidemia, and hyperlipidemia, is addressed.

Microcystin-LR acute exposure increases AChE activity via transcriptional ache activation in zebrafish (Danio rerio) brain

Microcystins (MCs) constitute a family of cyanobacterial toxins, with more than 80 variants. These toxins are able to induce hepatotoxicity in several organisms mainly through the inhibition of protein phosphatases PP1 and PP2A and oxidative stress generation. Since recent evidence shows that MCs can either accumulate in brain or alter behavior patterns of fish species, in this study we tested the in vitro and in vivo effects of MC-LR at different concentrations on acetylcholinesterase (AChE) activity in zebrafish brain. In vivo studies showed that 100 μg/L MC-LR led to a significant increase in the AChE activity (27%) when zebrafish were exposed to the toxin dissolved in water, but did not cause any significant changes when injected intraperitoneally. In addition, semiquantitative RT-PCR analysis demonstrated that 100 μg/L MC-LR exposure also increased ache mRNA levels in zebrafish brain. The in vitro assays did not reveal any significant changes in AChE activity. These findings provide the first evidence that brain AChE is another potential target for MCs and suggest that the observed increases in AChE enzymatic activity and in ache transcript levels after MC-LR exposure depend, at least partially, on branchial uptake or ingestion.

Zebrafish neurotransmitter systems as potential pharmacological and toxicological targets

Recent advances in neurobiology have emphasized the study of brain structure and function and its association with numerous pathological and toxicological events. Neurotransmitters are substances that relay, amplify, and modulate electrical signals between neurons and other cells. Neurotransmitter signaling mediates rapid intercellular communication by interacting with cell surface receptors, activating second messenger systems and regulating the activity of ion channels. Changes in the functional balance of neurotransmitters have been implicated in the failure of central nervous system function. In addition, abnormalities in neurotransmitter production or functioning can be induced by several toxicological compounds, many of which are found in the environment. The zebrafish has been increasingly used as an animal model for biomedical research, primarily due to its genetic tractability and ease of maintenance. These features make this species a versatile tool for pre-clinical drug discovery and toxicological investigations. Here, we present a review regarding the role of different excitatory and inhibitory neurotransmitter systems in zebrafish, such as dopaminergic, serotoninergic, cholinergic, purinergic, histaminergic, nitrergic, glutamatergic, glycinergic, and GABAergic systems, and emphasizing their features as pharmacological and toxicological targets. The increase in the global knowledge of neurotransmitter systems in zebrafish and the elucidation of their pharmacological and toxicological aspects may lead to new strategies and appropriate research priorities to offer insights for biomedical and environmental research.