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Ethanol alters the homeostasis between excitatory and inhibitory neurotransmitters and its intoxication reveals adenosine as responsible to modify several responses including signal transduction. Zebrafish has been recently investigated for knowledge the prolonged effect of ethanol on behavioral and biochemical parameters. The aim of this study was to evaluate the soluble and membrane adenosine deaminase activities and gene expression in zebrafish brain. Animals were exposed to 0.5% ethanol for 7, 14, and 28 days. There were no significant changes in ADA activity from soluble fraction after all treatments. However, we verified a decrease of ADA activity in membrane fraction after 28 days (44%) of ethanol exposure. ADA1 was not altered whereas mRNA transcript levels for ADAL presented an increase after 28 days of ethanol exposure (34%). ADA2-1 showed a decrease (26%) followed by an increase (17%) of transcripts after 14 and 28 days of ethanol exposure, respectively. However, ADA2-1 truncated alternative splice isoform (ADA2-1/T) demonstrated a reduction after 28 days (20%). ADA2-2 was decreased (22%) followed by an increase (109%) of transcripts after 14 and 18 days of ethanol exposure, respectively. Altogether, the purine catabolism promoted by ADA may be an important target of the chronic toxicity induced for ethanol. [ABSTRACT FROM AUTHOR]

Ethanol is a widely consumed drug that acts on the central nervous system (CNS), modifying several signal transduction pathways activated by hormones and neurotransmitters. The zebrafish is an experimental model for the study of human diseases and the use of this species in biochemical and behavioral studies on alcoholism and alcohol-dependence has increased recently. However, there are no data concerning the effects of chronic ethanol exposure on the purinergic system, where extracellular nucleotides act as signaling molecules. Purinergic signaling is controlled by a group of enzymes named ectonucleotidases, which include NTPDases and ecto-5′-nucleotidase already characterized in zebrafish brain. The aim of this study was to evaluate nucleotide hydrolysis by NTPDases and ecto-5′-nucleotidase after long-term ethanol exposure. Additionally, the gene expression patterns of NTPDases1–3 and 5′-nucleotidase were determined. Animals were exposed to 0.5% ethanol for 7, 14, and 28 days. There were no significant changes in ATP and GTP hydrolysis after all treatments. However, a decrease in ADP (46% and 34%) and GDP (48% and 36%) hydrolysis was verified after 7 and 14 days, respectively. After 7 and 14 days of ethanol exposure, a significant decrease in AMP hydrolysis (48% and 36%) was also observed, whereas GMP hydrolysis was inhibited only after 7 days (46%). NTPDase2_mv and NTPDase3 mRNA transcript levels decreased after 7 and 14 days, respectively. In contrast, ethanol increased NTPDase1, NTPDase2_mq, and NTPDase3 transcript levels after 28 days of exposure. NTPDase2_mg and 5′-nucleotidase gene expression was not altered. Therefore, the ectonucleotidase pathway may be a target of chronic ethanol toxicity and the regulation of purinergic system could play a key role in the neurochemical mechanisms underlying the effects of ethanol on the CNS. [ABSTRACT FROM AUTHOR]

Abstract: Alcohol abuse is an acute health problem throughout the world and alcohol consumption is linked to the occurrence of several pathological conditions. Here we tested the acute effects of ethanol on NTPDases (nucleoside triphosphate diphosphohydrolases) and 5′-nucleotidase in zebrafish (Danio rerio) brain membranes. The results have shown a decrease on ATP (36.3 and 18.4%) and ADP (30 and 20%) hydrolysis after 0.5 and 1% (v/v) ethanol exposure during 60min, respectively. In contrast, no changes on 5′-nucleotidase activity were observed in zebrafish brain membranes. Ethanol in vitro did not alter ATP and ADP hydrolysis, but AMP hydrolysis was inhibited at 0.5, and 1% (23 and 28%, respectively). Acetaldehyde in vitro, in the range 0.5–1%, inhibited ATP (40–85%) and ADP (28–65%) hydrolysis, whereas AMP hydrolysis was reduced (52, 58 and 64%) at 0.25, 0.5 and 1%, respectively. Acetate in vitro did not alter these enzyme activities. Semi-quantitative expression analysis of NTPDase and 5′-nucleotidase were performed. Ethanol treatment reduced NTPDase1 and three isoforms of NTPDase2 mRNA levels. These findings demonstrate that acute ethanol intoxication may influence the enzyme pathway involved in the degradation of ATP to adenosine, which could affect the responses mediated by adenine nucleotides and nucleosides in zebrafish central nervous system. [Copyright &y& Elsevier]

Abstract: Alcohol abuse is a health problem throughout the world and alcohol consumption is linked to the occurrence of several pathological conditions. Acute ethanol administration exerts a variety of actions on the central nervous system (CNS). Zebrafish has been used as an attractive model system to investigate behavioral and neurochemical changes promoted by alcohol intoxication. Here we investigated the in vitro and in vivo effects promoted by ethanol and its metabolites on zebrafish brain acetylcholinesterase (AChE). There was a significant increase of AChE (33%) activity after acute 1% ethanol exposure. However, ethanol in vitro did not alter AChE activity. Acetaldehyde, the first metabolite of alcohol metabolism, promoted a dose-dependent decrease (15%, 27.5% and 46.5%) at 0.25%, 0.5% and 1%, respectively. Acetate, a product of acetaldehyde degradation, did not change AChE activity. Furthermore, the acute ethanol exposure was able to inhibit AChE transcripts at 0.5% and 1%. These findings suggest that the alterations on zebrafish AChE could reveal molecular mechanisms related to cholinergic signaling in alcoholism. [Copyright &y& Elsevier]

Highlights: [•] EtOH and ALD alter glutamate uptake in zebrafish brain structures. [•] The actions of EtOH and its metabolite are concentration and structure-dependent. [•] ALD induces more severe changes on neurochemical functions in zebrafish brain. [•] Neurotoxic effects of alcohol result in changes on MTT and LDH released. [Copyright &y& Elsevier]

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

Abstract: Ethanol (EtOH) is a drug widely consumed throughout the world that promotes several neurochemical disorders. Its deleterious effects are generally associated with modifications in oxidative stress parameters, signaling transduction pathways, and neurotransmitter systems, leading to distinct behavioral changes. Taurine (2-aminoethanesulfonic acid) is a β-amino acid not incorporated into proteins found in mM range in the central nervous system (CNS). The actions of taurine as an inhibitory neurotransmitter, neuromodulator, and antioxidant make it attractive for studying a potential protective role against EtOH-mediated neurotoxicity. In this study, we investigated whether acute taurine cotreatment or pretreatment (1 h) prevent EtOH-induced changes in acetylcholinesterase (AChE) activity and in oxidative stress parameters in zebrafish brain. The results showed that EtOH exposure (1% in volume) during 1 h increased AChE activity, whereas the cotreatment with 400 mg·L−1 taurine prevented this enhancement. A similar protective effect of 150 and 400 mg·L−1 taurine was also observed when the animals were pretreated with this amino acid. Taurine treatments also prevented the alterations promoted in superoxide dismutase and catalase activities by EtOH, suggesting a modulatory role in enzymatic antioxidant defenses. The pretreatment with 150 and 400 mg·L−1 taurine significantly increased the sulfydryl levels as compared to control and EtOH groups. Moreover, 150 and 400 mg·L−1 taurine significantly decreased thiobarbituric acid reactive species (TBARS) levels, but the cotreatment with EtOH plus 400 mg·L−1 taurine did not prevent the EtOH-induced lipoperoxidation. In contrast, the pretreatment with 150 and 400 mg·L−1 taurine prevented the TBARS increase besides decreased the basal levels of lipid peroxides. Altogether, our data showed for the first time that EtOH induced oxidative stress in adult zebrafish brain and reinforce the idea that this vertebrate is an attractive alternative model to evaluate the beneficial effect of taurine against acute EtOH exposure. [Copyright &y& Elsevier]

• Gallic acid positively modulates cholinergic damage caused by exposure to ethanol. • Gallic acid in isolation increases antioxidant activity in the zebrafish brain. • Oxidative stress induced by ethanol is regulated positively by gallic acid. Gallic acid (GA) is a polyphenolic compound that has attracted significant interest due to its antioxidant action through free radical elimination and metal chelation. Ethanol is a highly soluble psychoactive substance, and its toxicity is associated with oxidative stress. In this context, the purpose of the present study was to investigate the effect of GA on neurochemical changes in zebrafish brains exposed to ethanol. GA was first analyzed in isolation by treating the animals at concentrations of 5, 10, and 20 mg/L for 24 h and 48 h. The results revealed that the group exposed to 20 mg/L over a 24/48 h period exhibited increases in thiobarbituric acid reactive substance (TBA-RS) levels and 2′,7′-dichlorofluorescein (DCFH) oxidation, demonstrating a pro-oxidant profile. Moreover, decrease in acetylcholinesterase (AChE) enzyme activity was observed. To investigate the effects of GA after ethanol exposure, the animals were divided into four groups: control; those exposed to 0.5% ethanol for 7 days; those exposed to 0.5% ethanol for 7 days and treated with GA at 5 and 10 mg/L on day 8. Treatment with GA at 5 and 10 mg/L reversed impairment of choline acetyltransferase activity and the damage to TBA-RS levels, DCFH oxidation, and superoxide dismutase activity induced by ethanol. Results of the present study suggest that GA treatment (20 mg/L) appeared to disrupt oxidative parameters in the zebrafish brain. GA treatment at 5 and 10 mg/L reversed alterations to the cholinergic system induced by prolonged exposure to ethanol in the zebrafish brain, probably through an antioxidant mechanism. [ABSTRACT FROM AUTHOR]

Ethanol is a widely consumed substance throughout the world. During development it can substantially damage the human fetus, whereas the developing brain is particularly vulnerable. The brain damage induced by prenatal alcohol exposure may lead to a variety of long-lasting behavioral and neurochemical problems. However, there are no data concerning the effects of developmental ethanol exposure on the glutamatergic system, where extracellular glutamate acts as signaling molecule. Here we investigated the effect of ethanol exposure for 2 h (concentrations of 0.0%, 0.1%, 0.25%, 0.50%, and 1.00%) in embryos at 24 h post-fertilization (hpf) by measuring the functionality of glutamate transporters in the brain of adult (4 months) zebrafish. However, ethanol 0.1%, 0.25% and 0.50% decreased transport of glutamate to 81.96%, 60.65% and 45.91% respectively, when compared with the control group. Interestingly, 1.00% was able to inhibit the transport activity to 68.85%. In response to the embryonic alcohol exposure, we found impairment in the function of cerebral glutamate transport in adult fish, contributing to long-term alteration in the homeostasis glutamatergic signaling. [ABSTRACT FROM AUTHOR]

Binge drinking is characterized by excessive alcohol consumption in a short period of time and is associated with a poor quality of life. Zebrafish are commonly used to investigate neurochemical, behavioral, and genetic parameters associated with ethanol (EtOH) exposure. However, few studies have used zebrafish as a model to investigate binge EtOH exposure. In order to elucidate the potential neurobehavioral impairments evoked by binge EtOH exposure in zebrafish, animals were immersed in 1.4% EtOH for 30 min three consecutive times with intervals of one week. Neurobehavioral parameters were analyzed immediately following the third exposure, as well as 2 and 9 days later. Brain choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities were reduced 9 days after the treatment. Thiobarbituric acid-reactive species and dichlorodihydrofluorescein levels were increased immediately after the treatment, but both returned to normal levels 2 days after the treatment. Catalase and glutathione reductase were impaired 2 and 9 days after the treatment. No alteration was observed in superoxide dismutase and glutathione peroxidase activities. EtOH treatment did not alter brain expression of inflammatory genes such as il - 1 β, il - 10 , and tnf -α. Zebrafish displayed anxiolytic-like behavior immediately after the last exposure, though there was no behavioral alteration observed 9 days after the treatment. Therefore, binge EtOH exposure in zebrafish leads to long lasting brain cholinergic alteration, probably related to oxidative stress immediately after the exposure, which is independent of classical inflammatory markers. • Brain AChE and ChAT activities were reduced 9 days after weekly-binge EtOH exposure in zebrafish. • Oxidative stress and antioxidant enzymes were altered after weekly-binge EtOH exposure. • Zebrafish behavior was altered 2 days, but not 9 days, after weekly-binge EtOH exposure. [ABSTRACT FROM AUTHOR]

Binge drinking is defined as the infrequent consumption of excessive doses of alcohol in a short period of time. Zebrafish is a reliable model to investigate ethanol consumption impact on the CNS, including reward signaling like dopaminergic neurotransmission system. The aim of this study was to evaluate zebrafish brain dopaminergic parameters after intermittent weekly ethanol exposure (WEE), which mimics binge drinking. Thus, adult zebrafish were exposed to ethanol (1.4% v /v) for 30 min, once a week for three consecutive weeks. The groups were divided according to different time points after the third exposure and name as follow: immediately (WEE I), two days (WEE-2), and nine days (WEE-9) after last exposure to ethanol. Brain dopaminergic function was assessed by the activity of the dopamine transporters (DAT); monoamine oxidase (MAO) activity; dopamine and noradrenaline levels by chromatography. The WEE-I and WEE-2 groups presented a significant increase in DAT activity. The MAO activity was decreased for WEE-2 and WEE-9 groups. The WEE-2 and WEE-9 groups presented an increase in brain dopamine levels, while noradrenaline levels were not affected. Therefore, dopaminergic parameters are still altered two and nine days after the last ethanol exposure in this binge experimental model, resulting in a modulatory event in this neurotransmission pathway. Unlabelled Image • This study investigated the effects of weekly ethanol exposure in a zebrafish model. • Dopamine levels were increase 2 and 9-days after weekly-binge ethanol exposure. • Brain MAO activity was decreased after weekly-binge ethanol exposure. [ABSTRACT FROM AUTHOR]