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)
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)
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)
Exposure to agrichemicals can have deleterious effects on fish, such as disruption of the hypothalamus-pituitary-inter-renal axis (HPI) that could impair the ability of fish to respond to stressors. In this study, fingerlings of the teleost jundiá (Rhamdia quelen) were used to investigate the effects of the commonly used agrichemicals on the fish response(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)
Due to the proximity of crop and fish culture areas, some agrichemicals that could be harmful for fish could enter into fishponds by different ways, such as by leaching through rain. Rhamdia quelen (Teleostei) were exposed to sublethal concentrations of methyl parathion (MP), a glyphosate based herbicide (Gly), and tebuconazole (Teb). The liver of R. quelen(More)
The jundiá Rhamdia quelen (Quoy and Gaimard) is a teleost species from the Siluridae family and is an important species for aquaculture in temperate and subtropical climates. Gonad and blood tissue samples were taken from cultured jundiá females between 1998 and 1999. Plasma concentrations of 17beta-estradiol (E(2)), testosterone (T), 11-ketotestosterone(More)
The presence of fluoxetine in aquatic environments has been reported for decades. Here, we investigate the effects of exposure to fluoxetine on the stress response and osmoregulation in zebrafish. We show that stress response alters osmoregulation and that fluoxetine inhibits these stress-related changes in osmoregulation. The results suggest that the(More)
Here, we show that individually housed zebrafish presented a reduced cortisol response to an acute stressor (persecution with a pen net for 120 s) compared to zebrafish housed in groups of 10. We hypothesized that the cortisol response to stress was reduced in individually housed zebrafish because they depend solely on their own perceptions of the stressor,(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)