Disfunção autonômica cardíaca e expressão de FOS em núcleos do bulbo após indução de dor crônica difusa não-inflamatória em ratos

• Ano de defesa: 2013
• Autor(a) principal: Oliveira, Larissa Resende
• Orientador(a): Santana Filho, Valter Joviniano de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Ciências Fisiológicas
• Palavras-chave em Português: Dor crônica; Sistema nervoso central; Pressão arterial; Fibromialgia; Barorreflexo
• Palavras-chave em Inglês: Central nervous system; Chronic pain
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::FISIOLOGIA
• Link de acesso: https://ri.ufs.br/handle/riufs/3970

Fibromyalgia (FM) is characterized by chronic non-inflammatory widespread pain (CWP) and changes in sympathetic function. In attempt to elucidate the pathophysiological mechanisms of FM we used a well-established CWP animal model. We aimed to evaluate changes in cardiac autonomic balance and baroreflex function in response to CWP induction in rats. Therefore, it was used 30 male Wistar rats (250-350 g) with 2 to 3 months. CWP was induced by two injections of acidic saline (pH 4.0, n=16) five days apart into the left gastrocnemius muscle, whereas control animals were injected twice with normal saline (pH 7.2, n = 14). To evaluate changes in cardiovascular responses, one day after the second injection of acidic saline (n=8) or normal saline (n=6) animals were instrumentated to blood pressure recordings and posterior analysis of pulse interval (PI) and systolic arterial pressure (SAP) variability, and spontaneous baroreflex sensitivity (BRS) was performed. To determine the involvement of areas of the CNS (NTS , RVLM and CVLM ), two days after the second injection of acidic saline (n=8) or normal saline (n=8) animals were anesthetized, perfused, the brains removed and cut in a cryostat. The brain sections were subjected to immunofluorescence protocol for Fos protein. Results are expressed as mean ± SEM. Differences between groups were analyzed using by t test, paired and unpaired. Values of p < 0.05 were considered statistically significant. After induction of CWP, there was an increase of power in the low frequency (LF) band of PI spectrum (12.75±1.04 nu), a decrease in the high frequency (HF) band (87.25±1.04 nu) and an increase of LF/HF ratio (0.16±0.01), when compared to control animals (7.83±1.13 nu LF; 92.16±1.13 nu HF; 0.08±0.01 LF/HF). In addition, there was an increase of power in the LF band of SAP spectrum (7.93±1.39 mmHg2) when compared to control animals (2.97±0.61 mmHg2). BRS was lower in acidic saline injected rats (0.59±0.06 ms/mmHg) when compared to control animals (0.71±0.03 ms/mmHg). By immunofluorescence , we found that in all investigated areas the percentage of Fos immunoreactive cells was significantly higher ( p < 0.001) in saline acidic compared to neutral saline group. Our results showed that induction of CWP in rats shifts cardiac sympathovagal balance towards sympathetic predominance and decreases BRS, data which corroborate findings in humans with FM, and also that activation of NTS, CVLM and RVLM appears to indicate the involvement of these areas in an attempt to control the cardiac autonomic dysfunction.