Made available in DSpace on 2014-12-17T15:37:18Z (GMT). No. of bitstreams: 1 EzequielBN_DISSERT.pdf: 1434271 bytes, checksum: ec339b7b0edd61a2480b5454f9c82167 (MD5) Previous issue date: 2013-07-12 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The exposure to stressors produces physiological changes of the organism in order to adapt the individual to the environment. Depending on the type, intensity and duration, stress can affect some cognitive functions, particularly processes of learning and memory. Several studies have also proposed that some level of anxiety would be necessary for memory formation. In this context, memories of previously aversive experiences may determine the manner and intensity with which are expressed fear responses, which explains the great interest in analyzing both anxiety and memory in animals. In addition, males and females demonstrate different reactions in relation to stressful stimuli, showing different levels of anxiety and differences in processing of the acquisition, retention and recall of information. Based on this information, the present study aimed to verify the effect of stress on learning, memory and anxiety behavioral parameters in rats exposed at different types of stressors of long duration (seven consecutive days): restraint (4h/day), overcrowding (18h/day) and social isolation (18h/day) in the different phases of the estrous cycle. Our results showed that the stress induced by restraint and social isolation did not cause changes in the acquisition process, but impaired the recall of memory in rats. Furthermore, it is suggested a protective effect of sex hormones on retrieval of aversive memory, since female rats in proestrus or estrus phase, characterized by high estrogen concentrations, showed no aversive memory deficits. Furthermore, despite the increased plasma levels of corticosterone observed in female rats subjected to restraint stress and social isolation, anxiety levels were unaltered, compared to those various stress conditions. Animal models based on psychological and social stress have been extensively discussed in the literature. Correlate behavioral responses, physiological and psychological have contributed in increasing the understanding of stress-induced psychophysiological disorders / A exposi??o a fatores estressantes promove mudan?as fisiol?gicas adaptativas do organismo ao meio ambiente. Dependendo do tipo, da intensidade e dura??o, o estresse pode afetar algumas fun??es cognitivas, particularmente o processo de aprendizagem e de mem?ria. Alguns estudos tamb?m t?m proposto que a ansiedade, em certa medida, seria necess?ria para que ocorresse a forma??o da mem?ria. Neste contexto, mem?rias de experi?ncias aversivas anteriores podem determinar a maneira e a intensidade com que s?o expressas as respostas de medo, o que justifica o grande interesse em analisar simultaneamente ansiedade e mem?ria em animais. No mais, machos e f?meas apresentam rea??es distintas em rela??o a est?mulos estressores, mostrando diferentes n?veis de ansiedade e diferen?as no processamento da aquisi??o, reten??o e evoca??o de informa??es mnem?nicas. Frente a essas informa??es, o presente estudo teve como objetivo verificar o efeito do estresse em par?metros comportamentais de aprendizagem, mem?ria e ansiedade de ratas submetidas a diferentes tipos de estressores de longa dura??o, (sete dias consecutivos): conten??o (4h/dia), alta densidade populacional (18h/dia) e isolamento social (18h/dia), nas diferentes fases do ciclo estral. Nossos resultados mostraram que o estresse promovido pela conten??o e pelo isolamento social n?o promoveram altera??es no processo de aquisi??o, mas promoveu preju?zos na evoca??o da mem?ria de ratas. Al?m disso, sugere-se um efeito protetor dos horm?nios sexuais sobre a evoca??o da mem?ria aversiva, uma vez que ratas que estavam nas fases proestro ou estro, fase de altas concentra??es plasm?ticas de estr?genos, n?o apresentaram preju?zos na evoca??o dessa mem?ria. No mais, apesar do aumento dos n?veis plasm?ticos de corticosterona observado nas ratas submetidas ao estresse de conten??o e isolamento social, os n?veis de ansiedade permaneceram inalterados frente a essas diferentes condi??es de estresse. Modelos animais baseados em estresse psicol?gico e social t?m sido bastante abordados na literatura. Correlacionar respostas comportamentais, fisiol?gicas e psicol?gicas t?m contribu?do no aumento da compreens?o dos transtornos psicofisiol?gicos envolvidos na resposta de estresse

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-06-14T19:34:21Z No. of bitstreams: 1 2015 - Veronica Cristina Lopes Menezes.pdf: 1388664 bytes, checksum: eb95b2be98ffd5f3a96140f14377f8f2 (MD5) / Made available in DSpace on 2017-06-14T19:34:21Z (GMT). No. of bitstreams: 1 2015 - Veronica Cristina Lopes Menezes.pdf: 1388664 bytes, checksum: eb95b2be98ffd5f3a96140f14377f8f2 (MD5) Previous issue date: 2015-07-30 / CAPES / The distribution of estrogen receptors in brain structures that are envolved in the hidroelectrolyte balance such as the lamina terminalis (LT), subfornical organ (SFO) and dorsal raphe nucleus (DRN) demonstrated that estradiol can modulate important responses in body fluids. In the literature experimental data support that estrogen can increase the triptofan-hydroxilase type 2 , the main enzyme for the serotonin synthesis. The primary question here is whether or not differences in the baseline or stimulated intake are a function of different levels of circulating gonadal hormones in female ovariectomized rats. Female Wistar intact rats (~230 g) were previously aclimated in metabolic cages during 5 days and ad libitum access to water and hypertonic saline (1.8%) bottles and food. Room temperature was maintained at 22?2 ?C with 12:12 h light-dark cycle (lights off at 19:00). Rats were anesthetized with intraperitoneal injections of a mixture of ketamine (75 mg/kg) and xylazine (5 mg/kg) and then bilaterally ovariohysterectomized. There were four experimental groups: OVX (replaced with corn oil), 2,5 ?g/kg (E2 2,5), 10,0 ?g/kg (E2 10,0) and 40,0 ?g/kg (E2 40,0), daily during seven days, s.c. After 24 h of the surgery the hormonal replacement initiated (estradiol cypionate, EC, Pfizer, Animal Health). We did three experimental protocols: baseline evaluations, sodium depletion and fluid replacement. The estrogen replacement exibitted a dose dependent effect in the following parameters under basal conditions: daily body weight, daily urinary volume and daily food intake. After sodium depletion there were no difference in the urinary volume after 2 and 24 hours of the experiment. But after fluid reposition we observed a dose dependent effect in the ingestive behaviour of water and hypertonic saline intake in sodium depleted and control animals. Our data support that estradiol can alter the natriorexigenic and dipsogenic responses especially after sodium depletion depending of the estrogenic status. / A distribui??o de receptores estrog?nicos em estruturas centrais envolvidas na regula??o da homeostase hidroeletrol?tica como o ?rg?o vasculoso da l?mina terminal, n?cleo subfornicial, n?cleo dorsal da rafe indica que o estradiol pode atuar nessas estruturas em resposta a altera??es nos fluidos corporais. Nosso objetivo foi verificar se a reposi??o hormonal pode influenciar de maneira concentra??o-dependente o status hidroeletrol?tico e neuroend?crino de ratas castradas com reposi??o hormonal em diferentes doses de forma comparativa. Ratas Wistar (~230 g) foram previamente adaptadas, por 5 dias, em gaiolas metab?licas, com acesso ad libitum aos bebedouros volum?tricos de ?gua e salina hipert?nica e ao alimento, sendo mantidas sob ciclo claro-escuro de 12 horas em sala com temperatura controlada em 22??2 ?C. Ao final da adapta??o, as ratas previamente anestesiadas com cetamina (75 mg/kg) e xilazina (5 mg/kg) foram submetidas ? cirurgia de ovariectomia bilateral. Os animais foram divididos em 4 grupos: OVX, reposi??o com ?leo de milho), repostos com ?leo de milho cipionato de estradiol (E2) 2,5 ?g/kg (E2 2,5), 10,0 ?g/kg (E2 10,0) e 40 ?g/kg (E2 40,0). O tratamento de reposi??o foi feito pela via subcut?nea, diariamente durante 7 dias tendo sido iniciado no dia seguinte ? cirurgia. Foram realizados tr?s protocolos experimentais: avalia??o sob condi??es basais, deple??o de ?ons s?dio e reapresenta??o de fluidos. Neste estudo o estradiol apresentou efeito dose dependente nos seguintes par?metros sob condi??es basais: peso corporal di?rio, volume urin?rio di?rio, ingest?o de alimento di?rio. Ap?s deple??o de s?dio n?o houve diferen?a em rela??o ao volume urin?rio de 2 e de 24 horas ap?s o experimento. No entanto ap?s a reapresenta??o dos fluidos houve efeito dose-dependente no comportamento ingestivo de ?gua e de salina hipert?nica tanto nos animais depletados de s?dio quanto nos animais controles.Os dados suportam que o estradiol modula o comportamento ingestivo dos animais sob condi??es basais e ap?s a deple??o de s?dio.