SLEEP DEPRIVATION INDUCES PATHOLOGIC CHANGES IN RAT MASTICATORY MUSCLES: ROLE OF TOLL-LIKE PATHWAY AND ATROPHY

We evaluated the toll-like signaling pathway and atrophy after sleep deprivation (SD) in masseter and temporal muscles. Twenty-four animals were distributed into 3 groups (n = 8/each): control (CTL), subjected to SD for 96 hours (SD96), and subjected to SD for 96 hours plus 96 hours of sleep recovery (SDR). Histopathologic analysis revealed acute inflammatory cells, congested vessels, fibrosis, and high cellularity in both muscles submitted to SD. These morphologic alterations were not observed in the control group. In rats of SDR, the absence of inflammation was noticed in the masseter. In this group, cyclooxygenase 2 and tumor necrosis factor-α downregulation were detected when comparing with controls. MyD88 and pIKK decreased in SD96 and SDR groups being pNFKBp50 downregulated in SDR. MyD88 expression increased in temporal of rats submitted to SD96 and SDR. On the other hand, pIKK decreased the protein expression in groups SD96 and SDR, while pNFKBp50 showed a decreased protein expression in the SD96 group only. The activation of atrophy by MAFbx upregulation was detected in temporal muscle in SD96 and SDR. Our results show that SD is able to induce morphologic alterations in rat masticatory muscles. Toll-like signaling pathway and atrophy play important roles in etiopathogenesis induced by SD, being dependent on muscle type.