Navegando por Autor "OLIVEIRA, Caio Maximino de"

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Construct validity of behavioral models of anxiety: where experimental psychopathology meets ecology and evolution
(2010-06) OLIVEIRA, Caio Maximino de; BRITO, Thiago Marques de; GOUVEIA JUNIOR, Amauri
In experimental psychopathology, construct validity is usually enhanced by addressing theories from other fields in its nomological network. In the field of anxiety research, this construct is related to antipredator behavior, conserved across phylogeny in its functions and neural basis, but not necessarily on its topography. Even though the relations between behavioral models of anxiety and statements from behavioral ecology and evolutionary biology are commonly made in anxiety research, these are rarely tested, at least explicitly. However, in order to increase construct validity in experimental anxiety, testing predictions from those theories is highly desirable. This article discusses these questions, suggesting a few ways in which behavioral ecological and evolutionary hypotheses of anxiety-like behavior may be tested.
Acesso aberto (Open Access)
Influence of gender and estrous cycle in the forced swim test in rats
(2008-12) GOUVEIA JUNIOR, Amauri; AFONSECA, Taciana Lucas; OLIVEIRA, Caio Maximino de; DOMINGUEZ, Roberto; CARVALHO, Silvio Morato de
The present work aimed at studying the influence of the estrous cycle in the forced swim test, an animal model of depression. For this, 44 male and female Wistar rats were divided into five groups according to the hormonal state in the first day of the study: metaestrus (N = 12), diestrus (N = 8), proestrus (N = 7), estrous (N = 6) and males (N = 11). They were housed in groups of five, with water and food ad libitum under a 12/12 h light/dark cycle. Females were screened daily for the estrous cycle. The animals were subjected to two swimming sessions in a glass cylinder with water up to 15 cm at 28±2º C. The data of the first five minutes of a 15-min first session were compared to those of a 5-min second session 24 h later. The results indicate that the latency to the first immobility was substantially reduced in the second session and was longer for females in diestrus and proestrus in the first session. The results also indicate that females in diestrus and proestrus exhibited less immobility than males in the first session; females in diestrus also exhibited less immobility than females in metaestrus. Females in metaestrus and diestrus, as well as males, did not present the decrease in total immobility times in the second session. The present results are analyzed in terms of differential effects of progesterone and estrogen on a learning component and an affective component.
Acesso aberto (Open Access)
Modulation of nociceptive-like behavior in zebrafish (Danio rerio) by environmental stressors
(2011-06) OLIVEIRA, Caio Maximino de
Zebrafish have been demonstrated to react consistently to noxious chemical stimuli and present reliable phenotypes of stress, fear, and anxiety. In this article, we describe the modulation of nociceptive-like responses of zebrafish to fear-, stress-, and anxiety-eliciting situations. Animals were exposed to an alarm substance, confinement stress, or a novel environment before being injected with 1% acetic acid in the tail. The alarm substance and confinement stress reduced the display of erratic movements and tail-beating behavior elicited by acetic acid. The novelty of the environment, in contrast, increased the frequency of tail-beating behavior. The results suggest that descending modulatory control of nociception exists in zebrafish, with apparent fear- and stress-induced analgesia and anxiety-induced hyperalgesia.
Acesso aberto (Open Access)
Papel da serotonina no comportamento defensivo do paulistinha (Danio rerio Hamilton 1822) adulto: Diferenças entre modelos comportamentais, linhagens, e efeitos do estresse predatório agudo
(Universidade Federal do Pará, 2014-11-14) OLIVEIRA, Caio Maximino de; HERCULANO, Anderson Manoel
Anxiety disorders present the highest incidence in the world population among psychiatric disorders, and the clinical efficacy of anxiolytic drugs is low, partially due to lack of knowledge on the neurochemical bases of these disorders. To reach a more ample and evolutionarily grounded comprehension of these phenomena, the use of phylogenetically older species can be an interesting approach in the field of behavioral modeling; thus, we suggest the use of zebrafish (Danio rerio Hamilton 1822) in the attempt to understand the modulation of these behaviors by the serotonergic system. We demonstrate that extracellular serotonin levels in the brains of adult zebrafish exposed to the light/dark preference test [LDT] (but not to the novel tank test [NTT]) are increased in relation to animals which are handled, but not exposed to the apparatuses. Moreover, serotonin tissue levels levels in the hindbrain and forebrain are elevated by the exposure to the LDT, while tissue levels in the midbrain are elevated by exposure to the NTT. Extracellular serotonin levels correlate positively with scototaxis, thigmotaxis and risk assessment in the LDT and negatively with geotaxis in the NTT. Acute treatment with a low dose of fluoxetine (2.5 mg/kg) increases scototaxis, thigmotaxis, and risk assessment in the LDT, and decreases geotaxis and freezing and facilitates habituation in the NTT. Treatment with buspirone decreases scototaxis, thigmotaxis and freezing at 25 and 50 mg/kg in the LDT and decreases risk assessment at 50 mg/kg; in the NTT, both doses decrease geotaxis, while the highest dose decreases freezing and facilitates habituation. Treatment with WAY 100635 decreases scototaxis at 0.003 and 0.03 mg/kg, while only the highest dose decreases thigmotaxis and risk assessment in the LDT. In the NTT, both doses decrease geotaxis, while only the lower dose facilitates habituation and increases homebase time. Treatment with SB 224289 did not alter scototaxis, but increased risk assessment at 2.5 mg/kg; in the NTT, this drug decreased geotaxis and decreased erratic swimming at 2.5 and 5 mg/kg, while at 2.5 mg/kg it increased homebase time. Treatment with DL-para-clorophenylalanine (2 x 300 mg/kg injections, separated by 24 h) decreased scototaxis, thigmotaxis and risk assessment in the LDT, and increased geotaxis and homebase time and decreased habituation in the NTT. When animals were pre-exposed to a conspecific “alarm substance”, extracellular serotonin levels were raised in association with an increase in scototaxis, freezing and erratic swimming in the LDT; both behavioral and neurochemical effects were blocked by pre-treatment with fluoxetine (2,5 mg/kg), but not with WAY 100,635 (0,003 mg/kg). Animals from the leopard strain show increased scototaxis and risk assessment in the LDT, as well as increased 5-HT tissue levels in the encephalon; the behavioral phenotype is rescued by treatment with fluoxetine (5 mg/kg). These data suggest that the serotonergic system of zebrafish modulates behavior in the LDT and NTT in opposite ways; that the fright response produced by alarm substance seems to increase serotonergic activity, an effect which is possibly mediated by serotonin transporters; and that at least one high-anxiety mutant phenotype is associated with serotonin uptake. It is thus suggested that from a functional point of view serotonin increases anxiety and decreases fear in zebrafish.
Acesso aberto (Open Access)
Parâmetros da escototaxia como modelo comportamental de ansiedade no paulistinha (danio rerio, cyprinidae, pisces)
(Universidade Federal do Pará, 2011-02-24) OLIVEIRA, Caio Maximino de; GOUVEIA JUNIOR, Amauri; http://lattes.cnpq.br/1417327467050274
Certain teleost fishes present a behavioral trait of scototaxis, the preference for dark environ- ments and not bright ones. The present work tried to evaluate some parameters of the explora- tory behavior of the zebrafish (Danio rerio Hamilton 1822) in the black/white tank, aiming to establish the reliability of measures in different contexts. White compartment avoidance presents a biphasic pattern, with an increase in avoidance preceding a decrease (Experiment 1). This same avoidance does not habituate to repeated exposure, independently of the inter- session interval, on the contrary of total locomotion (Experiments 2 and 3); forced exposure to the white compartment does not alter the subsequent exploratory behavior (Experiment 4). These results suggest that novelty is not the controlling dimension of scototaxis; besides, these results also suggest that the preference for the Black compartment is not caused simply by avoidance of the white compartment, although this certainly has an important role. The role of the aversiveness of the white compartment was assessed in a second series of experi- ments. The illumination above the white compartment is an anxiogenic factor, since increas- ing it decreases the time spent in the white compartment without affecting total locomotion (Experiment 5). This phenomenon seems to be due to a decrease in the capacity to camouf- lage with the substrate (crypsis), since altering the color of the white compartment to grey increases its exploration, while altering the color of the black compartment to grey increases the time spent in the white compartment (Experiment 6). Besides, the increase in the propor- tion of the apparatus occupied by the white compartment (from 50% to 75%) decreases the time spent in it (Experiment 7). These results suggest that the white compartment is aversive, and therefore the preference for darkness is not caused simply by positive reinforcing proper- ties of the black compartment. Taken together, the results of both series of experiments sug- gest that scototaxis results from an approach-avoidance conflict. Experiment 8 represents a common environmental manipulation which alters anxiety in rodents, environmental enrich- ment; here, animals raised in an enriched aquarium for two weeks present less white avoid- ance. It is concluded that scototaxis has good construct validity.
Acesso aberto (Open Access)
The effects of diazepam on the elevated T-maze are dependent on the estrous cycle of rats
(2009-12) GOUVEIA JUNIOR, Amauri; ANTUNES, Gabriela; OLIVEIRA, Caio Maximino de; CARVALHO, Silvio Morato de
In order to determine the modulation of anxiolytic and panicolytic-like effects of diazepam by the hormonal cycle of female rats, male and female rats – the latter divided per estrous cycle phase (estrus, diestrus, metaestrus and proestrus) – were tested in the elevated T-maze, a behavioral model of panic and anxiety. Diazepam (0.5, 1.0 and 2.0 mg/kg) or saline solution was injected in individual animals that were submitted to one session in the elevated T-maze 25 min after drug/saline administration. The test consisted of three avoidance trials and one escape trial, separated by a 30 s interval, during which the animals were isolated in individual cages. The avoidance trials began with the animal being placed at the end of the maze's enclosed arm. The time necessary for the animal to leave the central square was considered as the response's latency. The trials that exceeded 300 s were considered as failures. Results demonstrate a decrease in the effects of diazepam in inhibitory avoidance (anxiety) trials in females in diestrus and proestrus, but no relation of gender or estrous cycle on diazepam effects on escape trials (fear). The results support the hypothesis that down-regulation of GABAA receptors by activation of nuclear estrogen receptors and induction of PKC-mediated GABAA receptor phosphorylation by activation of surface estrogen receptors in raphe neurons underlie the modulation of diazepam sensitivity by estrogen.