Sleep deprivation aggravates brain injury after experimental subarachnoid hemorrhage via TLR4-MyD88 pathway

Subarachnoid hemorrhage (SAH) is a life-threatening cerebrovascular disease, and most of the SAH patients experience sleep deprivation during their hospital stay. It is well-known that sleep deprivation is one of the key components of developing several neurological disorders, but its effect on brain damage after SAH has not been determined. Therefore, this study was designed to evaluate the effect of sleep deprivation using an experimental SAH model in rats. Induction of sleep deprivation for 24 h aggravated the SAH-induced brain damage, as evidenced by brain edema, neuronal apoptosis and activation of caspase-3. Sleep deprivation also worsened the neurological impairment and cognitive deficits after SAH. The results of immunostaining and western blot showed that sleep deprivation increased the activation of microglial cells. In addition, sleep deprivation differently regulated the expression of anti-inflammatory and pro-inflammatory cytokines. The results of immunofluorescence staining and western blot showed that sleep deprivation markedly increased the activation of Toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein 88 (MyD88). Mechanically, treatment with the TLR4 inhibitor TAK-242 or the MyD88 inhibitor ST2825 significantly attenuated the brain damage and neuroinflammation induced by sleep deprivation after SAH. In conclusion, our results indicate that sleep deprivation aggravates brain damage and neurological dysfunction following experimental SAH in rats. These effects were mediated by the activation of the TLR4-MyD88 cascades and regulation of neuroinflammation.