Estudo comparativo dos modelos animais de hipóxia intermitente e privação de sono em ratos
Arquivos
Data
2007
Autores
Perry, Juliana Cini 
Orientadores
Tufik, Sergio
Tipo
Tese de doutorado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A sindrome da apneia e hipoapneia obstrutiva do sono (SAOS) caracteriza-se por epis6dios recorrentes de obstrucao das vias aereas superiores e esta associada as comorbidades cardiovasculares e cognitivas. Nos pacientes apneicos nao e possivel determinar se essas consequencias estao relacionadas aos efeitos da hipoxia per se ou se ocorrem devido a fragmentacao do sono. Assim, propoe-se neste estudo a avaliacao das alteracoes comportamentais, cognitivas e cardiovasculares em um modelo animal que associa hipoxia a privacao de sono. Ratos Wistar machos adultos foram expostos a hipoxia intermitente (HI-ciclos de 2 min de 21 por cento a 10 por cento de O2) das 7 as 19h e/ou privacao de sono paradoxal (PSP) pelo metodo da plataforma unica durante tres ou quatro dias. Para observar os efeitos cronicos da exposicao a HI e/ou restricao de sono (RS), os animais foram expostos a hipoxia das 10 as 16h e/ou submetidos a RS das 16 as 10h do dia seguinte durante 21 dias. Os resultados obtidos nesse estudo indicam que a PSP induziu alteracoes comportamentais associadas a modificacao da neurotransmissao adrenergica. A exposicao cronica a HI reduziu a concentracao de noradrenalina no estriado, modulando seletivamente os sistemas de neurotransmissao sem modificar o comportamento e a funcao cognitiva dos ratos. No entanto, o aumento da atividade motora nos ratos do grupo RS nao foi associado a alteracoes nas concentracoes de catecolaminas e na expressao da enzima tirosina hidroxilase no sistema nervoso central. A exposicao a RS nao modificou a aquisicao e a retencao da memoria dos animais na tarefa de esquiva inibitoria; entretanto, durante a habituacao foi observado prejuizo cognitivo. A PSP e a RS modificaram os fatores bioquimicos associados ao risco cardiovascular. Embora as alteracoes induzidas pela HI nos parametros bioquimicos sanguineos sejam tempo-dependentes, a exposicao a HI associada a PSP reverteu as modificacoes induzidas pela PSP. Os resultados sugerem que a hipoxia e a privacao de sono modificam os sistemas nervoso central e cardiovascular por vias distintas
Obstructive sleep apnea (OSA) is characterized by repetitive obstruction of the upper airways resulting in pauses in breathing and subsequent oxygen desaturation and is associated with cardiovascular and cognitive comorbidities. However, it is not possible to determine whether such effects in apneic patients are related to hypoxia per se or whether they occur due to the frequency of arousals induced by breathing alterations during sleep. Thus, this study was designed to determine the isolated and combined effects of hypoxia and sleep loss in behavior, cognitive and blood parameters related to cardiovascular risk in rats. Wistar male rats were exposed to intermittent hypoxia (IH) during the light period (2 min room air - 2 min 10% O2 for 12h/day) and/or paradoxical sleep deprivation (PSD - 24h/day) using the single platform method. Consequences of chronic IH and/or sleep restriction (SR) exposure were examined after 21 consecutive days of the hypoxia protocol from 1000-1600h followed by an SR period of 18h (1600 -1000h). Results showed that PSD induced behavioral alterations associated to modification of adrenergic neurotransmission. Chronic exposure to IH reduced the concentration of norepinephine in the striatum, without modifying behavior and cognitive function in rats. Indeed, the increase of motor activity observed in rats of the SR group was not associated with the alterations in the concentration of catecholamine and tyrosine hydroxylase protein expression in the central nervous system. Exposure to SR did not affect acquisition/retention on the inhibitory avoidance task. PSD (4 days) and SR (21 days) modified the biochemical factors associated with cardiovascular risk. Although the alterations that were induced by IH in biochemical parameters of blood are time dependant, exposure to IH associated with PSD reversed the alterations induced by PSD. Our results suggest that hypoxia and sleep loss modify cardiovascular and central nervous systems in distinct ways.
Obstructive sleep apnea (OSA) is characterized by repetitive obstruction of the upper airways resulting in pauses in breathing and subsequent oxygen desaturation and is associated with cardiovascular and cognitive comorbidities. However, it is not possible to determine whether such effects in apneic patients are related to hypoxia per se or whether they occur due to the frequency of arousals induced by breathing alterations during sleep. Thus, this study was designed to determine the isolated and combined effects of hypoxia and sleep loss in behavior, cognitive and blood parameters related to cardiovascular risk in rats. Wistar male rats were exposed to intermittent hypoxia (IH) during the light period (2 min room air - 2 min 10% O2 for 12h/day) and/or paradoxical sleep deprivation (PSD - 24h/day) using the single platform method. Consequences of chronic IH and/or sleep restriction (SR) exposure were examined after 21 consecutive days of the hypoxia protocol from 1000-1600h followed by an SR period of 18h (1600 -1000h). Results showed that PSD induced behavioral alterations associated to modification of adrenergic neurotransmission. Chronic exposure to IH reduced the concentration of norepinephine in the striatum, without modifying behavior and cognitive function in rats. Indeed, the increase of motor activity observed in rats of the SR group was not associated with the alterations in the concentration of catecholamine and tyrosine hydroxylase protein expression in the central nervous system. Exposure to SR did not affect acquisition/retention on the inhibitory avoidance task. PSD (4 days) and SR (21 days) modified the biochemical factors associated with cardiovascular risk. Although the alterations that were induced by IH in biochemical parameters of blood are time dependant, exposure to IH associated with PSD reversed the alterations induced by PSD. Our results suggest that hypoxia and sleep loss modify cardiovascular and central nervous systems in distinct ways.
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Citação
PERRY, Juliana Cini. Estudo comparativo dos modelos animais de hipóxia intermitente e privação de sono em ratos. 2007. 200 f. Tese (Doutorado em Ciências) - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, 2007.