Leonardo José Gil Barcellos

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Zebrafish (Danio rerio) have emerged as a promising model organism to study development, toxicology, pharmacology, and neuroscience, among other areas. Despite the increasing number of studies using zebrafish, behavioral studies with this species are still elementary when compared to rodents. The aim of this study was to develop a model of unpredictable(More)
This study investigated differences in the cortisol response of fish at different developmental stages after exposure to an acute stressor. Three experiments using 126 fish each were performed using 3 different age groups of jundiá (Rhamdia quelen): fingerlings at 60 days of age, juveniles at 180 days, and adults at 360 days. In each experiment, the fish in(More)
This study investigated the influence of neonatal handling on behavioral and biochemical consequences of chronic mild stress (CMS) in adulthood. Male rat pups were submitted to daily tactile stimulation (TS) or maternal separation (MS), from postnatal day 1 (PND1) to postnatal day 21 (PND21), for 10 min/day. In adulthood, half the number of animals were(More)
In many vertebrate species, including humans, the developmental stage directly influences an organism's reactivity to stress. For instance, fishes appear to exhibit "stress insensitive" periods early in development, which contributes to important alterations in stress responses. This phenomenon raises the important question of whether size or age influences(More)
We investigated whether juveniles of the nocturnal fish jundiá (Rhamdia quelen) and the diurnal fish Nile tilapia (Oreochromis niloticus) are able to chemically communicate stress to conspecifics. Groups of 8 fish were reared in tanks under recirculated water (water exchanged among all the tanks) for each species. Fish were handled in half of the tanks(More)
The effects of ethanol exposure on Danio rerio have been studied from the perspectives of developmental biology and behavior. However, little is known about the effects of ethanol on the prey-predator relationship and chemical communication of predation risk. Here, we showed that visual contact with a predator triggers stress axis activation in zebrafish.(More)
Psychotropic medications are widely used, and their prescription has increased worldwide, consequently increasing their presence in aquatic environments. Therefore, aquatic organisms can be exposed to psychotropic drugs that may be potentially dangerous, raising the question of whether these drugs are attractive or aversive to fish. To answer this question,(More)
The zebrafish (Danio rerio) has become an emergent model organism for translational approaches focused on the neurobiology of stress due to its genetic, neuroanatomical, and histological similarities with mammalian systems. However, despite the increasing number of studies using zebrafish, reports examining the impact of stress on relevant neurochemical(More)
The presence of pharmaceutical products in the aquatic environment has been reported in several studies. However, the impact of these drugs on living organisms is still uncharacterized. Here, we investigated the effects of acute exposure to either diazepam or fluoxetine on the stress response in Danio rerio. We showed that diazepam and fluoxetine inhibited(More)
Living animals exploit information released from dead animals to conduct adaptive biological responses. For instance, a recently published study has shown that avoidance behavior is triggered by death-associated odors in zebrafish. Stress can clearly act as an adaptive response that allows an organism to deal with an imminent threat. However, it has not(More)