Characteristics of Muscle Fibers in Rats with Limb Movements during Sleep after Spinal Cord Injury

Background/Aims: Previous studies have demonstrated that spinal cord injury (SCI) results in changes in sleep patterns through increased arousals and limb movements during sleep. Dramatic changes in muscle myosin heavy-chain isoforms have also been reported. the aim of this study was to investigate the characteristics of muscle fibers after SCI in rats with limb movements during sleep. Methods: Forty male Wistar rats were divided into four groups: SHAM, SCI 3, 7 and 15 days. Animals were subjected to electrode insertion surgery, 24-hour baseline sleep recording, SCI, and subsequent sleep recording for 3, 7, or 15 consecutive days. in addition, the gastrocnemius muscle and spinal cord were collected for histopathological/histochemical analyses. Results: Our results indicate a rapid and progressive decrease in the cross-sectional area of type I fibers in the gastrocnemius muscle (35.76-24.74 mu m(2)) after SCI. Additionally, we found SCI-induced changes in sleep patterns. Following SCI, we also observed limb movements in sleeping rats, as well as significant negative moderate correlations between type I fibers and limb movement. Conclusion: Our study strengthened the hypothesis by correlation between changes in types of muscle fiber (decline in type I fibers) and an increase in limb movements during sleep after SCI. Copyright (c) 2012 S. Karger AG, BaselAssociacao Fundo Incentivo a Pesquisa (AFIP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Centro de Estudo Multidiciplinar em Sonolencia e Acidentes (CEMSA)Centro de Estudos em Psicobiologia e Exercicio (CEPE)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Dept Psicobiol, BR-04020050 São Paulo, BrazilFac Ciencias Med Santa Casa São Paulo, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psicobiol, BR-04020050 São Paulo, BrazilFAPESP: 03/06297-3FAPESP: CEPID 98/143033Web of Scienc