RESUMO
High ethanol (EtOH) consumption is a serious condition that induces tremors, alcoholic psychosis, and delirium, being considered a public health problem worldwide. Prolonged EtOH exposure promotes neurodegeneration, affecting several neurotransmitter systems and transduction signaling pathways. Glutamate is the major excitatory amino acid in the central nervous system (CNS) and the extracellular glutamatergic tonus is controlled by glutamate transporters mostly located in astrocytes. Here, we explore the effects of prolonged EtOH exposure on the glutamatergic uptake system and its relationship with astroglial markers (GFAP and S100B), neuroinflammation (IL-1ß and TNF-α), and brain derived neurotrophic factor (BDNF) levels in the CNS of adult zebrafish. Animals were exposed to 0.5% EtOH for 7, 14, and 28 days continuously. Glutamate uptake was significantly decreased after 7 and 14 days of EtOH exposure, returning to baseline levels after 28 days of exposure. No alterations were observed in crucial enzymatic activities linked to glutamate uptake, like Na,K-ATPase or glutamine synthetase. Prolonged EtOH exposure increased GFAP, S100B, and TNF-α levels after 14 days. Additionally, increased BDNF mRNA levels were observed after 14 and 28 days of EtOH exposure, while BDNF protein levels increased only after 28 days. Collectively, our data show markedly brain astroglial, neuroinflammatory and neurotrofic responses after an initial impairment of glutamate uptake following prolonged EtOH exposure. This neuroplasticity event could play a key role in the modulatory effect of EtOH on glutamate uptake after 28 days of continuous exposure.
Assuntos
Encéfalo/efeitos dos fármacos , Etanol/efeitos adversos , Gliose/induzido quimicamente , Ácido Glutâmico/metabolismo , Doenças Neuroinflamatórias/induzido quimicamente , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Feminino , Gliose/patologia , Interleucina-1beta/metabolismo , Masculino , Doenças Neuroinflamatórias/patologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , ATPase Trocadora de Sódio-Potássio/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Peixe-Zebra , Proteínas de Peixe-Zebra/metabolismoRESUMO
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 30â¯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 (WEEI), 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.
Assuntos
Encéfalo/patologia , Depressores do Sistema Nervoso Central/toxicidade , Neurônios Dopaminérgicos/efeitos dos fármacos , Etanol/toxicidade , Animais , Química Encefálica/efeitos dos fármacos , Dopamina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Neurônios Dopaminérgicos/patologia , Masculino , Monoaminoxidase/metabolismo , Norepinefrina/metabolismo , Transmissão Sináptica/efeitos dos fármacos , Peixe-ZebraRESUMO
Valproic acid (VPA) is an antiepileptic drug (AED) that has the broadest spectrum across all types of seizures and epileptic syndromes. Unfortunately, approximately 30% of epileptic patients are refractory to the classical AED. Metal ions have been frequently incorporated into pharmaceuticals for therapeutic or diagnostic purposes and research. In this preliminary study, we assess the embryo toxicity and the anticonvulsant activity of 4 novel metallodrugs, with Zn+2 and Cu+2, a derivative of valproic acid and the N-donor ligand in an adult zebrafish epileptic seizure model induced by pentylenetetrazole. The most toxic complex was [Cu(Valp)2Bipy], in which the LC50 was 0.22⯵M at 48â¯h post fertilization (HPF) and 0.12⯵M at 96 HPF, followed by [Zn(Valp)2Bipy] (LC50â¯=â¯10⯵M). These same metallodrugs ([Cu(Valp)2Bipy] 10â¯mM/kg and [Zn(Valp)2Bipy] 30â¯mM and 100â¯mM/kg) displayed superior activity, thus reducing the seizure intensity by approximately 20 times compared to sodium valproate (175â¯mM/kg). Overall, [Cu(Valp)2Bipy] showed the best anticonvulsant effects. However, because of the toxicity of copper, [Zn(Valp)2Bipy] is considered the most promising anticonvulsant for future studies.
Assuntos
Anticonvulsivantes/farmacologia , Cobre/farmacologia , Teratogênicos/farmacologia , Ácido Valproico/farmacologia , Compostos de Zinco/farmacologia , Animais , Anticonvulsivantes/química , Anticonvulsivantes/toxicidade , Cobre/química , Cobre/toxicidade , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/patologia , Epilepsia/tratamento farmacológico , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Compostos Organometálicos/toxicidade , Pentilenotetrazol , Dados Preliminares , Convulsões/tratamento farmacológico , Teratogênicos/química , Teratogênicos/toxicidade , Ácido Valproico/química , Ácido Valproico/toxicidade , Peixe-Zebra , Compostos de Zinco/química , Compostos de Zinco/toxicidadeRESUMO
Fetal Alcohol Spectrum Disorders (FASD) is a syndrome characterized by neurological and behavioral impairments. A recently discovered hallmark of FASD is impaired social behavior. Avoidance of social interaction typical of FASD may be the result of increased anxiety. Previously, the zebrafish was successfully used to model embryonic alcohol induced social abnormalities. Here, we analyzed both anxiety and social responses using a zebrafish FASD model, in adult fish. We exposed zebrafish embryos to low concentrations of ethanol (0.1%; 0.25%; 0.5% and 1% v/v) for 2h at, 24h post-fertilization, to mimic the most prevalent milder FASD cases, and investigated the ensuing alterations in adult, 4-month-old, zebrafish. We studied social interaction in the social preference task and anxiety in the novel tank task. We observed an ethanol dose dependent reduction of time spend in the conspecific zone compared to control, corroborating prior findings. We also found significant changes in the novel tank (e.g. increased bottom dwell time, increased distance to top) suggesting elevated anxiety to control, but we also found, using an anxiolytic drug buspirone, that reduction of anxiety is associated with reduced shoaling. Our results confirm that embryonic alcohol exposure disrupts social behavior, and also show that its effects on anxiety related phenotypes may be genotype, alcohol administration method, experimental procedure and test-context dependent.
Assuntos
Ansiedade/etiologia , Transtornos do Espectro Alcoólico Fetal/psicologia , Comportamento Social , Animais , Ansiolíticos/farmacologia , Ansiedade/tratamento farmacológico , Aprendizagem da Esquiva/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Buspirona/farmacologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Embrião não Mamífero/efeitos dos fármacos , Etanol/toxicidade , Feminino , Masculino , Distribuição Aleatória , Peixe-ZebraRESUMO
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 2h (concentrations of 0.0%, 0.1%, 0.25%, 0.50%, and 1.00%) in embryos at 24h 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.
Assuntos
Comportamento Animal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Embrião não Mamífero/efeitos dos fármacos , Etanol/farmacologia , Ácido Glutâmico/metabolismo , Animais , Transporte Biológico , Encéfalo/metabolismo , Embrião não Mamífero/metabolismo , Fatores de Tempo , Peixe-Zebra/embriologiaRESUMO
BACKGROUND: Step-down inhibitory avoidance task has been widely used to evaluate aversive memory, but crucial parameters inherent to traditional devices that may influence the behavior analysis (as stimulus frequency, animal's bioimpedance) are frequently neglected. NEW METHOD: We developed a new device for step-down inhibitory avoidance task by modifying the shape and distribution of the stainless steel bars in the box floor where the stimuli are applied. The bars are 2 mm wide, with rectangular shape, arranged in pairs at intervals of 1cm from the next pairs. Each pair makes an electrical dipole where the polarity inverts after each pulse. This device also presents a component that acquires and records the exact current received by the animal foot and precisely controls the frequency of stimulus applied during the entire experiment. RESULT: Different from conventional devices, this new apparatus increases the contact surface with bars and animal's paws, allowing the electric current pass through the animal's paws only, drastically reducing the influence of animal's bioimpedance. The analysis of recorded data showed that the current received by the animal was practically the same as applied, independent of the animal's body composition. Importantly, the aversive memory was observed at specific stimuli intensity and frequency (0.35 or 0.5 mA at 62 and 125 Hz but not at 0.20 mA or 20 Hz). Moreover, with this device it was possible to observe the well-known step-down inhibitory avoidance task memory impairment induced by guanosine. CONCLUSION: This new device offers a substantial improvement for behavioral analysis in step-down inhibitory avoidance task and allows us to precisely compare data from different animals with distinct body composition.
Assuntos
Aprendizagem da Esquiva/fisiologia , Comportamento Animal/fisiologia , Composição Corporal/fisiologia , Memória/fisiologia , Animais , Impedância Elétrica , Eletrochoque , Ratos , Ratos WistarRESUMO
Pentylenetetrazole (PTZ) is a common convulsant agent used in animal models to investigate the mechanisms of seizures. Although adult zebrafish have been recently used to study epileptic seizures, a thorough characterization of the PTZ-induced seizures in this animal model is missing. The goal of this study was to perform a detailed temporal behavior profile characterization of PTZ-induced seizure in adult zebrafish. The behavioral profile during 20 min of PTZ immersion (5, 7.5, 10, and 15 mM) was characterized by stages defined as scores: (0) short swim, (1) increased swimming activity and high frequency of opercular movement, (2) erratic movements, (3) circular movements, (4) clonic seizure-like behavior, (5) fall to the bottom of the tank and tonic seizure-like behavior, (6) death. Animals exposed to distinct PTZ concentrations presented different seizure profiles, intensities and latencies to reach all scores. Only animals immersed into 15 mM PTZ showed an increased time to return to the normal behavior (score 0), after exposure. Total mortality rate at 10 and 15 mM were 33% and 50%, respectively. Considering all behavioral parameters, 5, 7.5, 10, and 15 mM PTZ, induced seizures with low, intermediate, and high severity, respectively. Pretreatment with diazepam (DZP) significantly attenuated seizure severity. Finally, the brain PTZ levels in adult zebrafish immersed into the chemoconvulsant solution at 5 and 10 mM were comparable to those described for the rodent model, with a peak after a 20-min of exposure. The PTZ brain levels observed after 2.5-min PTZ exposure and after 60-min removal from exposure were similar. Altogether, our results showed a detailed temporal behavioral characterization of a PTZ epileptic seizure model in adult zebrafish. These behavioral analyses and the simple method for PTZ quantification could be considered as important tools for future investigations and translational research.