A redução da temperatura corpórea durante a separação materna no período neonatal reduz de modo assimétrico os níveis de dopamina cortical de camundongos adolescentes

• Ano de defesa: 2019
• Autor(a) principal: Cordeiro, Marcelle da Cunha
• Orientador(a): Filgueiras, Cláudio Carneiro
• Banca de defesa: Manhães, Alex Christian , Carvalho, Anderson Ribeiro , Kubrusly, Regina Célia Cussa
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Fisiopatologia Clínica e Experimental
• Departamento: Centro Biomédico::Faculdade de Ciências Médicas
• País: BR
• Palavras-chave em Português: Estresse; Isolamento neonatal; Saúde da criança; Cuidado Pré-Natal; Isolamento de pacientes
• Palavras-chave em Inglês: Stress; Neonatal isolation
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::FISIOLOGIA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/12714

In humans, prenatal stress is associated with a wide range of neurobehavioral disorders that can be observed from infancy to adulthood. Studies in rodents have provided a considerable advance in the understanding of the mechanisms involved with the pathogenesis of these disorders. Particularly, locomotor hyperactivity has been associated with increased neuroapoptosis rate and hypofunction of the dopaminergic mesocorticolimbic pathways. In a recent study in mice submitted to maternal separation stress during the neonatal period, we suggest that hypothermia during the isolation period is a fundamental condition for the manifestation of locomotor hyperactivity at adolescence. The aim of the present study was evaluated, in mice model of maternal separation, whether temperature during the period of isolation affects the levels of catecholamines in the cortex and the population of dopaminergic neurons in the ventral tegument area (VTA). Swiss mice were submitted to daily maternal separation sessions between PN2 to PN10 (PN1 = birth day), varying the isolation temperature of the pup, which remained at the approximate temperature of the nest (37 °C, Heated Group) or maintained at the temperature of the vivarium (between 22 and 25 oC, Unheated Group). Animals that were not manipulated from PN2 to PN10 formed the Control group. At PN35, some animals had the anterior portion of the cortex removed for evaluation of the levels of dopamine, dihydroxyphenylacetic acid (DOPAC) and noradrenaline by high performance liquid chromatography. Another sample of mice had the brains coronally sliced into a vibratome (20 μm thick) for the identification of dopaminergic neurons in the VTA by immunohistochemical tyrosine hydroxylase labeling. Our data show that while the body temperature of the animals in the Heat Group did not change after isolation period, body temperature decreased 6 oC in Unheated Group. The mortality rate of the Unheated Group was higher than that of the Control and Heated Groups. The dopamine levels of the Unheated Group were lower than that the other groups and this effect was more pronounced in the right hemisphere than in the left hemisphere. The DOPAC and noradrenaline levels were not affected by neonatal isolation. The number of dopaminergic neurons in VTA also did not differ between groups. Therefore, our data suggest that hypothermia during neonatal isolation promoted a reduction in cortical dopaminergic function without affecting the number of neurons in VTA. This result corroborates the idea of temperature control is a critical factor for the manifestation of neurobehavioral disorders observed in the model of stress due to maternal separation in the neonatal period.