Padrão de sono em modelo experimental de osteoartrite

• Ano de defesa: 2009
• Autor(a) principal: Silva, Andressa [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: Dor crônica; Gênero; Osteoartrite; Ratos; Sono; Dor/classificação
• Link de acesso: http://repositorio.unifesp.br/handle/11600/9895

Osteoarthritis (OA) is a major health issue and its prevalence has increased in the past decades. OA is characterized by the degeneration of joint cartilage, a condition associated to chronic pain and sleep disturbances. It has been shown that the relation between pain and sleep produces adverse effects in the sleep pattern and in pain perception. Because electrophysiological investigations in animal pain models are still limited the current study purported to examine sleep architecture and sensitivity to thermal stimulation within the framework of an experimental OA model in male rats (Paper 1). And also, to assess how this OA model influences the sleep pattern and hormonal profile (progesterone, estradiol and testosterone) in both genders (Paper 2). Wistar rats were used in all of the experimental protocols. Electrodes were implanted for the recording of electrocortigrams. OA was induced by means of intra-articular administration of iodineacetate in the left knee. Sleep recordings were monitored during the light and dark periods (12h each) and these were analyzed at the beginning of the study before administration iodineacetate and on days 1, 10, 15, 20 and 28 after the injection of iodineacetate. OA animals were compared to SHAM groups (vehicle) and controls (not manipulated). Paper 1 also assessed the threshold of pain in the hot plate test in and additional group of animals on the same days. The results of Paper 1 showed that OA induced a significant reduction in the threshold of thermal pain from the 10th day to the end of the experiment. Analysis of the sleep recordings showed that the male OA rats suffered alteration in the sleep pattern like reduction in the efficiency of sleep, slow wave sleep, paradoxical sleep, but increased number of awakenings during the light period when compared to the baseline period, SHAM groups and controls. Results collected from paper 2 show that OA rats, regardless of the gender, presented fragmentation in the sleep pattern with reduced sleep efficiency, slow wave sleep and paradoxical sleep, as well as shorter paradoxical sleep episodes. However, in the dark period, male rats presented lower sleep efficiency and slow wave sleep in comparison to females. In addition, OA affected concentrations of male hormones, once those of testosterone were significantly reduced in comparison to controls and SHAM. In females, progesterone and estradiol remained unaltered throughout the investigation. Our results suggest that the OA model does promote marked alterations in sleep architecture in males as well as in females, and is associated to lower pain thresholds and smaller levels of hormones in the blood.