Efeitos neurohistológicos e comportamentais após hipoperfusão cerebral crônica no rato: influência da idade a do conjunto de vasos ocluídos

• Ano de defesa: 2008
• Autor(a) principal: Barros, Carla Aparecida de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Departamento de Farmácia e Farmacologia; Programa de Pós-Graduação em Ciências Farmacêuticas; UEM; Maringá, PR; Centro de Ciências da Saúde
• Palavras-chave em Português: Hipoperfusão cerebral crônica e progressiva; Lesão de retina; Artérias carótidas; Modelo 4-VO permanente; Aprendizagem; Memória; Danos neurais; Brasil.; Chronic and progressive cerebral hypoperfusion; Retinal degeneration; Neural demage; Learning; Memory; Stepwise 3-stage-4-VO; Brazil.; Ciências da Saúde; Farmácia
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/1931

Continuing with the view to the development of a permanent, 3-stage, 4-vessel occlusion (4-VO) model of chronic and progressive cerebral hypoperfusion in rats, here we evaluated how the set of vessels that are occluded and the age of animal affect (i) the ability for spatial learning, (ii) the hippocampal cell density and (iii) the morfological integrity of retina. Bilateral occlusion of the vertebral arteries (VA) was combined with stepwise ligation of the common carotid arteries (CCA) (4-VO/CCA model) or internal carotid arteries (ICA) (VO/ICA model), with 1-week inter-stage interval. The effects of 4-VO/CCA were evaluated in young rats, while the effects of 4-VO/ICA were assessed in young, adult or old rats. Forthy days after completion of the 4-VO stage, or sham-operation, the rats were tested in the aversive radial maze for 15 consecutive days, after which the brain and eyes were examined for ischemic damage. Compared to sham, the 4-VO/CCA young rats exhibited cognitive impairment (P < 0.0001 - 0.05), hippocampal damage (P < 0.01), and retinal degeneration (P< 0.05). Compared to control, the 4-VO/CCA group did not benefit from the effect of training sessions (P > 0.05). In contrast, neither learning deficit nor hippocampal, or retinal damage were observed in both young and adult rats subjected to the 4-VO/ICA procedure. In old rats, chronic 4-VO/ICA caused a mild learning deficit, expressed significantly for the parameter 'latency' (P < 0.05). A highly significant effect of training was observed for the old, shamoperated rats (P < 0.0001 - 0.001), but not for the old 4-VO/ICA rats (P > 0.05). In average, hippocampal cell density was not changed after 4-VO/ICA in old rats, but when analysed individually, 3 of 10 subjects exhibited reduced pyramidal cells in all hippocampal sectors. The morphology of retina appeared unaffected. These date suggest that the 4-VO/ICA model of chronic cerebral hypoperfusion is a more suitable paradigm given the apparent functional preservation of the visual system, which integrity is important when spatial behavior is to be measured. Moreover, the age at which 4-VO/ICA is imposed represent an important factor for determining the behavioral and neuropatholoical changes.