RESUMO
Contextual fear conditioning is a protocol used to assess associative learning across species, including fish. Here, our goal was to expand the analysis of behavioral parameters that may reflect aversive behaviors in a contextual fear conditioning protocol using adult zebrafish (Danio rerio) and to verify how such parameters can be modulated. First, we analyzed the influence of an aversive stimulus (3 mild electric shocks for 5 s each at frequencies of 10, 100 or 1000 Hz) on fish behavior, and their ability to elicit fear responses in the absence of shock during a test session. To confirm whether the aversive responses are context-dependent, behaviors were also measured in a different experimental environment in a test session. Furthermore, we investigated the effects of dizocilpine (MK-801, 2 mg/kg, i.p.) on fear-related responses. Zebrafish showed significant changes in baseline activity immediately after shock exposure in the training session, in which 100 Hz induced robust contextual fear responses during the test session. Importantly, when introduced to a different environment, animals exposed to the aversive stimulus did not show any differences in locomotion and immobility-related parameters. MK-801 administered after the training session reduced fear responses during the test, indicating that glutamate NMDA-receptors play a key role in the consolidation of contextual fear-related memory in zebrafish. In conclusion, by further exploring fear-related behaviors in a contextual fear conditioning task, we show the effects of different shock frequencies and confirm the importance of context on aversive responses for associative learning in zebrafish. Additionally, our data support the use of zebrafish in contextual fear conditioning tasks, as well as for advancing pharmacological studies related to associative learning in translational neurobehavioral research.
Assuntos
Comportamento Animal , Condicionamento Clássico , Maleato de Dizocilpina , Eletrochoque , Antagonistas de Aminoácidos Excitatórios , Medo , Peixe-Zebra , Animais , Medo/efeitos dos fármacos , Medo/fisiologia , Maleato de Dizocilpina/farmacologia , Condicionamento Clássico/efeitos dos fármacos , Condicionamento Clássico/fisiologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Comportamento Animal/efeitos dos fármacos , Masculino , Aprendizagem por Associação/efeitos dos fármacos , Aprendizagem por Associação/fisiologia , Feminino , Locomoção/efeitos dos fármacosRESUMO
Impulse control disorders (ICDs) are characterized by generalized difficulty controlling emotions and behaviors. ICDs are a broad group of the central nervous system (CNS) disorders including conduct disorder, intermittent explosive, oppositional-defiant disorder, antisocial personality disorder, kleptomania, pyromania and other illnesses. Although they all share a common feature (aberrant impulsivity), their pathobiology is complex and poorly understood. There are also currently no ICD-specific therapies to treat these illnesses. Animal models are a valuable tool for studying ICD pathobiology and potential therapies. The zebrafish (Danio rerio) has become a useful model organism to study CNS disorders due to high genetic and physiological homology to mammals, and sensitivity to various pharmacological and genetic manipulations. Here, we summarize experimental models of impulsivity and ICD in zebrafish and highlight their growing translational significance. We also emphasize the need for further development of zebrafish ICD models to improve our understanding of their pathogenesis and to search for novel therapeutic treatments.
Assuntos
Doenças do Sistema Nervoso Central , Transtornos Disruptivos, de Controle do Impulso e da Conduta , Animais , Transtornos Disruptivos, de Controle do Impulso e da Conduta/terapia , Comportamento Impulsivo , Modelos Animais , Peixe-ZebraRESUMO
The organic selenium compound diphenyl diselenide (DD) has been recognized as an antioxidant and neuroprotective agent, exerting an anti-hyperglycemic effect in experimental models of diabetes. However, the precise mechanisms involved in the protection are unclear. Using the zebrafish (Danio rerio) as a model organism, here we investigated biomarkers underlying the protective effects of DD against hyperglycemia, targeting in a transcriptional approach the redox and insulin-signaling pathway. Fish were fed on a diet containing DD (3â¯mg/kg) for 74 days. In the last 14 days, they were exposed to a 111â¯mM glucose solution to induce a hyperglycemic state. DD reduced blood glucose levels as well as normalized the brain mRNA transcription of four insulin receptors-coding genes (Insra1, Insra2, Insrb1, Insrb2), which were down-regulated by glucose. DD alone caused an up-regulation of relative mRNA transcription in both Insra receptors and glucose transporter 3 genes. DD counteracted hyperglycemia-induced lipid peroxidation, protein and thiol depletion. Along with the decreased activity of antioxidant enzymes SOD and GPx, the brain of hyperglycemic fish presented a reduction in mRNA transcription of FoxO3A, FoxO3B, Nrf2, GPx3A, SOD1, and SOD2 genes. Besides normalizing the transcriptional levels, DD caused an up-regulation of relative mRNAs that encode Nrf2, FoxO1A, FOXO3A, GPx4A, PTP1B, AKT and SelP. Collectively, our findings suggest that the antioxidant and anti-hyperglycemic actions of DD in a zebrafish diabetes model are likely associated with the regulation of the oxidative stress resistance and the insulin-signaling pathway and that could be related to the modulation at mRNA level of two important transcription factors, Nrf2 and FoxO.
Assuntos
Antioxidantes , Peixe-Zebra , Animais , Antioxidantes/farmacologia , Derivados de Benzeno , Hipoglicemiantes , Insulina , Compostos Organosselênicos , Oxirredução , Estresse Oxidativo , Transdução de SinaisRESUMO
The object discrimination test allows the testing of different memory retention periods. However, few behavioral endpoints have been measured in fish species such that retention is often assessed using a single parameter (time spent in object area). Here, we aimed to explore the object discrimination test in zebrafish by assessing their behavioral performance after 1 or 24 h retention interval periods. To characterize putative interaction-like behaviors, fish were tested in the absence or presence of scopolamine (1 h before test session). Zebrafish were habituated for 3 consecutive days in the experimental tank, and training session was performed for 10 min using two identical nonpreferred objects (black cube or sphere). After the retention intervals, a familiar object was replaced by a novel object (test session, 10 min). Fish were also exposed to the novel tank diving test to assess locomotion and anxiety-like behaviors. At 1 h retention interval, animals performed more circular-like investigation near the familiar object, whereas 24 h after training session, a prominent rapid investigation was observed when animals explore the nonfamiliar object. Because scopolamine abolished these phenotypes, as well as the increased time spent in the novel object area during the test without changing locomotion and anxiety-related parameters, the behavioral responses described here may predictively reflect interaction-like behaviors involved in object discrimination memory in zebrafish models.
Assuntos
Cognição/efeitos dos fármacos , Transtornos da Memória/fisiopatologia , Nootrópicos/farmacologia , Reconhecimento Visual de Modelos/efeitos dos fármacos , Escopolamina/farmacologia , Peixe-Zebra/fisiologia , Animais , Transtornos da Memória/induzido quimicamenteRESUMO
Epilepsy is characterized by abnormal and recurrent hyperexcitability in brain cells. Various comorbidities are associated with epilepsy, including irritability and aggressive behavior. Aggression is a negative effect observed in epileptic patients that may be harmful to other individuals, impairing social relations. Thus, developing novel experimental models to assess behavioral phenotypes that may comorbid with neurological disorders are of great interest. Here, we investigate whether pentylenetetrazole (PTZ) increases aggression in zebrafish following a single exposure. Animals were exposed to 10 mM PTZ for 20 min and aggression-towards mirror was measured at different time intervals after recovering period (1 h, 3 h, 6 h, 24 h, 48 h, and 72 h). We observed that zebrafish showed exacerbated aggression, as well as an increased number of entries in the virtual conspecific area from 1 h to 48 h after PTZ. However, no behavioral differences were observed after 72 h. Overall, our novel findings show that a single PTZ exposure evokes aggression in a time-dependent manner, reinforcing the use of zebrafish models to explore epilepsy-related comorbidities.
Assuntos
Agressão/efeitos dos fármacos , Antagonistas GABAérgicos/administração & dosagem , Pentilenotetrazol/administração & dosagem , Convulsões/induzido quimicamente , Animais , Comportamento Animal/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Masculino , Peixe-ZebraRESUMO
Epilepsy is a common neurological disorder characterized by recurrent unprovoked seizures, which culminate in various neurobehavioral and neurochemical changes. Taurine (TAU) is an amino sulfonic acid which acts an endogenous inhibitory neuromodulator. Moreover, TAU displays intrinsic antioxidant activity, contributing to its beneficial actions in the CNS. Here, we evaluated whether TAU pretreatment protects from pentylenetetrazole (PTZ)-induced behavioral alterations and oxidative stress-related parameters in zebrafish brain tissue. Fish were pretreated with 42, 150, and 400 mg/L TAU (40 min) and further exposed to 10 mM PTZ (20 min) to analyze the seizure-like behaviors. As a positive control, another group was previously treated with 75 µM diazepam (DZP). Afterwards, biochemical experiments were performed. All TAU concentrations tested decreased seizure intensity in the first 150 s. Importantly, 150 mg/L TAU attenuated seizure-like behavioral scores, decreased seizure intensity, reduced the frequency of clonic-like seizures (score 4), and increased the latency to score 4. TAU (150 mg/L) also prevented oxidative stress in PTZ-challenged fish by decreasing lipid peroxidation and protein carbonylation and preventing changes on nonprotein thiol levels. No significant changes were observed in MTT assay and LDH activity. Differently than observed in DZP group, TAU did not affect the overall swimming activity of fish, suggesting different mechanisms of action. Collectively, we show that TAU attenuates PTZ-induced seizure-like behaviors and brain oxidative stress in zebrafish, suggesting the involvement of antioxidant mechanisms in neuroprotection.
Assuntos
Comportamento Animal/efeitos dos fármacos , Química Encefálica/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Taurina/farmacologia , Peixe-Zebra/metabolismo , Animais , Antioxidantes , Encéfalo/efeitos dos fármacos , Encéfalo/enzimologia , Encéfalo/patologia , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Diazepam/farmacologia , Feminino , Masculino , Neuroquímica , Estresse Oxidativo/efeitos dos fármacos , Pentilenotetrazol , Fenótipo , Carbonilação Proteica/efeitos dos fármacos , Convulsões/patologia , Natação , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Meloxicam is an anti-inflammatory drug that has a potential protective effect in many common diseases. However, this molecule is quickly eliminated from the body due to it short half-life. One way to overcome this problem is to incorporate meloxicam into lipid-core nanocapsules which may increase it anti-inflammatory effects. In view of this, the objective of this work was to evaluate the potential toxicity and safety of these novel nanomaterials both in vitro and in vivo. Here, we evaluated the effects of uncoated meloxicam-loaded nanocapsules (M-NC), uncoated and not loaded with meloxicam or blank (B-NC), PEGylated meloxicam-loaded lipid-core nanocapsules (M-NCPEG), blank PEGylated lipid-core nanocapsules (B-NCPEG) and free meloxicam (M-F) in vitro through the analysis of cell viability, caspase activity assays and gene expression of perforin and granzyme B. Meanwhile, the in vivo safety was assessed using C57BL/6 mice that received nanocapsules for seven days. Thus, no change in cell viability was observed after treatments. Furthermore, M-NC, M-NCPEG and M-F groups reversed the damage caused by H2O2 on caspase-1, 3 and 8 activities. Overall, in vivo results showed a safe profile of these nanocapsules including hematological, biochemical, histological and genotoxicity analysis. In conclusion, we observed that meloxicam nanocapsules present a safe profile to use in future studies with this experimental protocol and partially reverse in vitro damage caused by H2O2.
Assuntos
Anti-Inflamatórios não Esteroides , Caspases/metabolismo , Linfócitos/efeitos dos fármacos , Meloxicam , Nanocápsulas/química , Polietilenoglicóis/química , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Anti-Inflamatórios não Esteroides/toxicidade , Peso Corporal/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Dano ao DNA , Ingestão de Alimentos/efeitos dos fármacos , Humanos , Peróxido de Hidrogênio/toxicidade , Linfócitos/enzimologia , Linfócitos/patologia , Masculino , Meloxicam/farmacologia , Meloxicam/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Especificidade de Órgãos , Baço/efeitos dos fármacos , Baço/patologia , Testes de ToxicidadeRESUMO
The zebrafish (Danio rerio) is an emergent model organism for assessing fear and anxiety-like phenotypes. The short fin wild type (WT), and leopard (leo) are two zebrafish populations that present several behavioral differences, in which leo displays pronounced defensive responses. Mounting evidence suggests a modulatory role for cholinergic and purinergic signaling in fear and anxiety, but the involvement of these neurotransmitter systems in the behavioral profile of zebrafish is obscure. Here we tested whether the acute exposure to conspecific alarm substance (AS), an experimental protocol that induces fear, alters shoaling behavior, diving response, acetylcholinesterase (AChE) activity, and nucleotide hydrolysis in brain tissue of WT and leo. When four fish were concomitantly exposed to AS extracted from a donor fish of similar phenotype, both populations presented a significant increase of erratic movements without changes in freezing bouts. An increased shoal cohesion and a decreased vertical distribution were observed only in WT exposed to AS. The respective population also revealed a significant increase in AChE and ecto-5'-nucleotidase activities after the exposure period. The comparison of basal endpoints between populations showed that leo displays a higher social cohesion, few vertical transitions and enhanced AChE and ecto-5'-nucleotidase activities. In conclusion, we suggest that the effects of AS on defensive behaviors depend on the population, indicating the existence of distinct neurochemical mechanisms involved. Furthermore, this report shows the first evidence of a potential role of cholinergic and purinergic systems in fear- and anxiety-like responses of zebrafish populations.
Assuntos
5'-Nucleotidase/metabolismo , Acetilcolinesterase/metabolismo , Ansiedade/metabolismo , Comportamento Animal/fisiologia , Reação de Fuga/fisiologia , Medo , Análise de Variância , Animais , Animais Geneticamente Modificados , Área Sob a Curva , Feminino , Masculino , Peixe-Zebra , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
Paraquat (PQ) administration consists in a chemical model that mimics phenotypes observed in Parkinson's disease (PD), due to its ability to induce changes in dopaminergic system and oxidative stress. The aim of this study was to evaluate the actions of PQ in behavioral functions of adult zebrafish and its influence on oxidative stress biomarkers in brain samples. PQ (20 mg/kg) was administered intraperitoneally with six injections for 16 days (one injection every 3 days). PQ-treated group showed a significant decrease in the time spent in the bottom section and a shorter latency to enter the top area in the novel tank test. Moreover, PQ-exposed fish showed a significant decrease in the number and duration of risk assessment episodes in the light-dark test, as well as an increase in the agonistic behavior in the mirror-induced aggression (MIA) test. PQ induced brain damage by decreasing mitochondrial viability. Concerning the antioxidant defense system, PQ increased catalase (CAT) and glutathione peroxidase (GPx) activities, as well as the non-protein sulfhydryl content (NPSH), but did not change ROS formation and decreased lipid peroxidation. We demonstrate, for the first time, that PQ induces an increase in aggressive behavior, alters non-motor patterns associated to defensive behaviors, and changes redox parameters in zebrafish brain. Overall, our findings may serve as useful tools to investigate the interaction between behavioral and neurochemical impairments triggered by PQ administration in zebrafish.
Assuntos
Antioxidantes/metabolismo , Comportamento Animal/efeitos dos fármacos , Lesões Encefálicas/patologia , Paraquat/toxicidade , Peixe-Zebra/fisiologia , Agressão/efeitos dos fármacos , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Comportamento Exploratório/efeitos dos fármacos , Feminino , Locomoção/efeitos dos fármacos , MasculinoRESUMO
Alcohol is a potent agent for eliciting aggression in vertebrates. Taurine (TAU) is an amino sulfonic acid with pleiotropic actions on brain function. It is one of the most abundant molecules present in energy drinks frequently used as mixers for alcoholic beverages. However, the combined effects of TAU and ethanol (EtOH) on behavioral parameters such as aggression are poorly understood. Considering that zebrafish is a suitable vertebrate to assess agonistic behaviors using noninvasive protocols, we investigate whether TAU modulates EtOH-induced aggression in zebrafish using the mirror-induced aggression (MIA) test. Since body color can be altered by pharmacological agents and may be indicative of emotional state, we also evaluated the actions of EtOH and TAU on pigment response. Fish were acutely exposed to TAU (42, 150, and 400mg/L), EtOH (0.25%), or cotreated with both molecules for 1h and then placed in the test apparatus for 6min. EtOH, TAU 42, TAU 400, TAU 42/EtOH and TAU 400/EtOH showed increased aggression, while 150mg/L TAU only increased the latency to attack the mirror. This same concentration also prevented EtOH-induced aggression, suggesting that it antagonizes the effects of acute alcohol exposure. Representative ethograms revealed the existence of different aggressive patterns and our results were confirmed by an index used to estimate aggression in the MIA test. TAU did not alter pigment intensity, while EtOH and all cotreated groups presented a substantial increase in body color. Overall, these data show a biphasic effect of TAU on EtOH-induced aggression of zebrafish, which is not necessarily associated with changes in body color.