3-(2-4-dichloro-5-methoxyphenyl)-2-sulfanyl-4(3h)-quinazolinone and Subarachnoid-Hemorrhage

The NLRP3 inflammasome functions as a crucial component of the inflammatory response in early brain injury (EBI) after subarachnoid hemorrhage (SAH). However, the mechanisms underlying the activation of NLRP3 inflammasome has not been well elucidated. In this study, we hypothesized the RIP1-RIP3-DRP1 pathway was involved in the activation of the NLRP3 inflammasome following SAH. SAH was induced by endovascular perforation in rats. Necrostatin-1 (Nec-1) or mitochondrial division inhibitor (Mdivi-1) was administered 1h after SAH by intraperitoneal injection. SAH grade, neurological function, brain water content, Western blot, ROS assay, immunofluorescence and transmission electron microscopy were performed. SAH led to the upregulation of RIP1, RIP3, phosphorylated DRP1 and NLRP3 inflammasome. Nec-1 treatment reduced RIP1, RIP3, phosphorylated DRP1 and NLRP3 inflammasome, subsequently alleviated brain edema and neurological deficits at 24h following SAH. The treatment with Mdivi-1 inhibited the expression of DRP1 protein, attenuated mitochondria damage and the generation of ROS, inhibited NLRP3 inflammasome and ameliorated brain edema and neurological deficits at 24h after SAH. The activation of the NLRP3 inflammasome in EBI after SAH was mediated by RIP1-RIP3-DRP1 pathway. Nec-1 and Mdivi-1 can inhibit inflammation and improve neurological function after SAH.

Topics: Animals; Body Water; Caspase 1; Dynamins; Gene Expression Regulation; Imidazoles; Indoles; Inflammasomes; Male; NLR Family, Pyrin Domain-Containing 3 Protein; Protein Serine-Threonine Kinases; Quinazolinones; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Receptor-Interacting Protein Serine-Threonine Kinases; Signal Transduction; Subarachnoid Hemorrhage

Aberrant modulation of mitochondrial dynamic network, which shifts the balance of fusion and fission towards fission, is involved in brain damage of various neurodegenerative diseases including Parkinson's disease, Huntington's disease and Alzheimer's disease. A recent research has shown that the inhibition of mitochondrial fission alleviates early brain injury after experimental subarachnoid hemorrhage, however, the underlying molecular mechanisms have remained to be elucidated. This study was undertaken to characterize the effects of the inhibition of dynamin-related protein-1 (Drp1, a dominator of mitochondrial fission) on blood-brain barrier (BBB) disruption and neuronal apoptosis following SAH and the potential mechanisms. The endovascular perforation model of SAH was performed in adult male Sprague Dawley rats. The results indicated Mdivi-1(a selective Drp1 inhibitor) reversed the morphologic changes of mitochondria and Drp1 translocation, reduced ROS levels, ameliorated the BBB disruption and brain edema remarkably, decreased the expression of MMP-9 and prevented degradation of tight junction proteins-occludin, claudin-5 and ZO-1. Mdivi-1 administration also inhibited the nuclear translocation of nuclear factor-kappa B (NF-κB), leading to decreased expressions of TNF-ɑ, IL-6 and IL-1ß. Moreover, Mdivi-1 treatment attenuated neuronal cell death and improved neurological outcome. To investigate the underlying mechanisms further, we determined that Mdivi-1 reduced p-PERK, p-eIF2α, CHOP, cleaved caspase-3 and Bax expression as well as increased Bcl-2 expression. Rotenone (a selective inhibitor of mitochondrial complexes I) abolished both the anti-BBB disruption and anti-apoptosis effects of Mdivi-1. In conclusion, these data implied that excessive mitochondrial fission might inhibit mitochondrial complex I to become a cause of oxidative stress in SAH, and the inhibition of Drp1 by Mdivi-1 attenuated early brain injury after SAH probably via the suppression of inflammation-related blood-brain barrier disruption and endoplasmic reticulum stress-based apoptosis.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Blood-Brain Barrier; Claudin-5; Dynamins; Endoplasmic Reticulum Stress; Interleukin-1beta; Interleukin-6; Male; Matrix Metalloproteinase 9; Mitochondria; Mitochondrial Dynamics; NF-kappa B; Occludin; Proto-Oncogene Proteins c-bcl-2; Quinazolinones; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Subarachnoid Hemorrhage; Subarachnoid Space; Survival Analysis; Tumor Necrosis Factor-alpha; Zonula Occludens-1 Protein

Mdivi-1 is a selective inhibitor of mitochondrial fission protein, Drp1, and can penetrate the blood-brain barrier. Previous studies have shown that Mdivi-1 improves neurological outcomes after ischemia, seizures and trauma but it remains unclear whether Mdivi-1 can attenuate early brain injury after subarachnoid hemorrhage (SAH). We thus investigated the therapeutic effect of Mdivi-1 on early brain injury following SAH. Rats were randomly divided into four groups: sham; SAH; SAH + vehicle; and SAH + Mdivi-1. The SAH model was induced by standard intravascular perforation and all of the rats were subsequently sacrificed 24 h after SAH. Mdivi-1 (1.2 mg/kg) was administered to rats 30 min after SAH. We found that Mdivi-1 markedly improved neurologic deficits, alleviated brain edema and BBB permeability, and attenuated apoptotic cell death. Mdivi-1 also significantly reduced the expression of cleaved caspase-3, Drp1 and p-Drp1

Topics: Animals; Brain Injuries; Dynamins; Male; Mitochondrial Dynamics; Oxidative Stress; Quinazolinones; Rats; Rats, Wistar; Subarachnoid Hemorrhage