Avaliação Do Comportamento Social, Do Tipo-Ansioso E Da Resposta De Corticosterona Em Ratos Machos E Fêmeas Adolescentes Submetidos À Privação Materna No Período Neonatal

• Ano de defesa: 2017
• Autor(a) principal: Ceschim, Viviane Cortes [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: Maternal Deprivation; Neonatal Stress; Adolescence; Anxiety; Social Behavior; Privação Materna; Estresse Neonatal; Comportamento Social; Adolescência; Ansiedade; Corticosterona
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5077817; http://repositorio.unifesp.br/handle/11600/50415

Introduction: Early life adversity represents major risk factors for stress-related psychiatric disorders, such as anxiety and depression. These pathological conditions are characterized by impairment of social behavior, reflected by avoidance of social interaction. Among the numerous models of childhood adversity, 24 h of maternal deprivation can be considered a transient loss of maternal care, displaying the advantage of pointing out to the importance of age and, consequently, of the ontogenesis, for the outcomes of this manipulation on the brain and behavior developmental trajectory. Objectives: In the present study, anxiety-like behavior was evaluated in the open field, social interest and corticosterone response to the social investigation test, in male and female adolescent rats that were either non-manipulated – control (CTL), maternally-deprived on postnatal day (PND) 3 (DEP3) or on PND 11 (DEP11), tested between PNDs 40 and 45. Methods: Twenty four litters were distributed throughout the three groups, CTL, DEP3 and DEP11. Each litter was standardized to contain four males and four females on PND 1. On the day of maternal deprivation (PND 3 or PND 11), whole litters were removed from the maternity-cage and placed in another cage containing clean sawdust, mixed with nest material. This cage was placed on a heating pad adjusted to 30 to 33oC, in order to mimic the nest temperature, for 24 h. At the end of the deprivation period, the litters were reunited with their dams and remained together, without any disruption, except from routine cage cleaning, until weaning on PND 21. Between PNDs 40 and 45, two males and two females from each litter were assigned to non-tested animals, in order to provide for basal corticosterone plasma levels, whereas the remainder were exposed to the open field, for 10 min, for habituation to and assessment of anxiety-like behavior and during the session locomotion in the central and peripheral segments was counted. On the next day, 24 h after the anxiety-like behavior assessment, the same animals were exposed to the social investigation test, which consisted of placing them, individually, in the center of the open field, containing two metal baskets: one was empty and the other enclosed a target rat, of the same sex and age as the experimental animal. During the 10 min session, the experimental animal could explore the baskets and the environment and the ratio of empty:target baskets exploration was calculated. All session were videorecorded and analyzed offline. Thirty min after the social investigation test, or at the corresponding moment for non-tested rats, animals were blood sampled by decapitation, in order to provide basal and post-test corticosterone plasma levels. After the blood sampling, the phase of the estrous cycle was checked. Results: DEP3 females in proestrous ambulated less in the center of the open field than CTL and DEP11 females in the same estrous phase. Males, on the other hand, displayed reduced social investigation ratio, when compared with CTL and DEP11 counterparts. The social test elicited a hormonal response that was similar for all groups and sexes, e.g., regardless of the group and sex, post-test corticosterone plasma levels were higher than basal. Conclusion: These results suggest that maternal deprivation had a higher impact on anxiety-like behavior when it happened earlier than later in development, with an evident sexual dimorphism.