Navegando por Autor "NASCIMENTO, Gabriela Souza do"

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Acesso aberto (Open Access)
Desamparo aprendido com o zebrafish (Danio rerio)
(Universidade Federal do Pará, 2014-05-23) NASCIMENTO, Gabriela Souza do; GOUVEIA JUNIOR, Amauri; http://lattes.cnpq.br/1417327467050274
Exposure to uncontrollable aversive events leads to difficulty in learning contingency relations, escape and/or avoidance. Such phenomenon was named learned helplessness and it has been correlated to depression and post-traumatic stress disorder. This thesis is composed by three studies that together have the aim of: producing learned helplessness in Danio rerio (Study I); investigating the effects of light on the escape test (Study II) and evaluating the effects imipramine have on learned helplessness when applied acutely in Danio rerio (Study III). In every experiment it was used an acrylic shutllebox (INSIGHT equipment) which contained a central area (removable) that enabled the isolation of the subjects. The general protocol consisted in two phases: 1) Treatment, each subject of the Uncontrollable shock (USH) treatment was subjected to 60 random and uncontrollable shocks (0.7 – 0.9V, lasting 30 seconds each), in this phase the subjects of the group that didn't receive treatment with electric shock (NSH) only remained in the central area for 60 minutes; and 2) Test, each subject from both groups was subjected to an escape session with 30 shocks (0.7 – 0.9V, maximum duration of 30 seconds each). In Study I, 3 groups were used, one experimental (EGUSH) and two controls, one remaining in the experimental aquarium for 60 minutes without shock (CG-NSH). In Study II, 4 groups were used, a pair from NSH and USH subjected to the light test, another pair (NSH and USH) underwent the test no light condition. In Study III 6 groups were used according to the concentration of imipramine administered during 10 minutes before the test session: 0.0 mg/l NCH; 0.0 mg/CHI; 1.0 mg/l NCH; 1.0 mg/l CHI; 2.0 mg/l NCH; e 2.0 mg/l CHI. The main results show that it is possible to create learned helplessness in Danio rerio (study I), considering light as a variable that can interfere directly in the acquisition of the phenomenon (study II), in addition, it was showed that acute imipramine in the doses administered here did not revert the learned helplessness in Danio rerio.
Acesso aberto (Open Access)
Subchronic effects of fluoxetine on conditioned suppression produced by a hot air blast
(2012-06) NASCIMENTO, Gabriela Souza do; MONTEIRO, Patrícia Caroline Madeira; GOUVEIA JUNIOR, Amauri; CARVALHO NETO, Marcus Bentes de
Conditioned suppression is an animal model of anxiety disorders that has been broadly used to investigate the behavioral effects of different drugs. However, various methodological variables (e.g., the type of aversive stimulus) that supposedly interfere with the acquisition of conditioned suppression may also contribute to conflicting results among the studied drugs. Additionally, few studies have sought to investigate the effects of selective serotonin reuptake inhibitors (SSRIs). The present study investigated the effect of subchronic 5-day administration of 5 mg/kg fluoxetine in the retention of conditioned suppression produced by a hot air blast (HAB). The subjects were 12 albino Wistar rats distributed into an Experimental Group (EG) and Control Group (CG). After sessions were conducted to pair two stimuli, a sound and HAB, fluoxetine (EG) or saline (CG) was administered. Twentyfour hours after the last injection, a test session was conducted. The results showed no difference between groups. Fluoxetine (5 mg/kg) did not exert anxiolytic effects in this model of conditioned suppression produced by a HAB. Keywords: conditioned suppression; fluoxetine; subchronic; hot air blast.
Acesso aberto (Open Access)
Supressão condicionada com diferentes estímulos aversivos: choque elétrico e jato de ar quente
(Universidade Federal do Pará, 2009-07-23) NASCIMENTO, Gabriela Souza do; CARVALHO NETO, Marcus Bentes de; http://lattes.cnpq.br/7613198431695463
A neutral stimulus, once paired to an aversive unconditional stimulus, acquires aversive function of (conditional) and, indirectly, is also able to suppress operant response. This phenomenon was called of "conditioned suppression" and is connected to certain emotional states such as anxiety. The literature shows that, in general, aversive unconditional stimulus used is limited to electric shock: few alternative aversive stimuli tested have been proven effective. However, independently of shock when an aversive unconditional there are other variables that can directly influence the appearance of the phenomenon. In the present study, we examined and compared the production of conditioned suppression with two different aversive stimuli: hot air puff (HAP) and electric shock. Four albino rats were used (Rattus norvegicus, Wistar). The apparatus was two rodent operant conditioning chambers, one for the electric shock and another for a HAP. The subjects were divided into pairs and exposed to the pairing of a neutral stimulus with different aversive stimuli: sound + HAP (J1 and J2 Subject) and sound + electric shock (C1 and C2 Subject). The main results indicated that: when aversive stimulus was electric shock, the suppression was total (suppression ratio equals to 0.0) after 2(C1) or 3(C2) pairings. When aversive stimulus was HAP, the suppression was partial, and were necessary 8 (J1) and 7 (J2) parings to produce suppression ratio equals to 0.5, for one subject, and 0.2 to another. The analysis of other responses showed that on average there was an increase of 83.3% (J1) and 275% (J2) on the frequency of exploratory responses during the presentation of sound, in sessions of pairing with HAP, compared with the presentation of sound in the sessions of habituation, whereas for the subjects exposed to the shock was paired with a deletion of 44.2% (C1) and 57.1% (C2) in such responses. These data show that the suppression caused by the pairing of sound + shock to affect other classes of responses, different from the sound paired with HAP. The suppression produced by HAP seems to have been a result of the increase the in the frequency of exploratory responses. It is possible that the parameter intensity of HAP used in this experiment, was responsible for results. Future researchs are suggested to elucidate this aspect.