title: Norrin protected blood-brain barrier via frizzled-4/β-catenin pathway after subarachnoid hemorrhage in rats.
abstract: OBJECTIVE
  Norrin and its receptor Frizzled-4 have important roles in the blood-brain barrier development. This study is to investigate a potential role and mechanism of Norrin/Frizzled-4 on protecting blood-brain barrier integrity after subarachnoid hemorrhage (SAH).
  
  
  METHODS
  One hundred and seventy-eight male Sprague-Dawley rats were used. SAH model was induced by endovascular perforation. Frizzled-4 small interfering RNA was injected intracerebroventricularly 48 hours before SAH. Norrin was administrated intracerebroventricularly 3 hours after SAH. SAH grade, neurological scores, brain water content, Evans blue extravasation, western blots, and immunofluorescence were used to study the mechanisms of Norrin and its receptor regulation protein TSPAN12, as well as neurological outcome.
  
  
  RESULTS
  Endogenous Norrin and TSPAN12 expression were increased after SAH, and Norrin was colocalized with astrocytes marker glial fibrillary acidic protein in cortex. Exogenous Norrin treatment significantly alleviated neurobehavioral dysfunction, reduced brain water content and Evans blue extravasation, promoted β-catenin nuclear translocation, and increased Occludin, VE-Cadherin, and ZO-1 expressions. These effects were abolished by Frizzled-4 small interfering RNA pretreated before SAH.
  
  
  CONCLUSIONS
  Norrin protected blood-brain barrier integrity and improved neurological outcome after SAH, and the action of Norrin appeared mediated by Frizzled-4 receptor activation, which promoted β-catenin nuclear translocation, which then enhanced Occludin, VE-Cadherin, and ZO-1 expression. Norrin might have potential to protect blood-brain barrier after SAH.
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Yujie
authors.initials: Y
authors.lastname: Chen
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Junjia
authors.initials: J
authors.lastname: Tang
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Qin
authors.initials: Q
authors.lastname: Hu
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Chunxia
authors.initials: C
authors.lastname: Luo
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Jiping
authors.initials: J
authors.lastname: Tang
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.).
authors.forename: Hua
authors.initials: H
authors.lastname: Feng
authors.affiliation: From the Departments of Neurosurgery (Y.C., H.F.) and Neurology (C.L.), Southwest Hospital, Third Military Medical University, Chongqing, China; and Department of Physiology and Pharmacology, Loma Linda University, CA (Y.C., Y.Z., J.T., F.L., Q.H., J.T., J.H.Z.). johnzhang3910@yahoo.com fenghua8888@vip.163.com.
authors.forename: John H
authors.initials: JH
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D005136:Eye Proteins / Q000008:administration & dosage / Q000096:biosynthesis*; D051157:Frizzled Receptors / Q000096:biosynthesis*; D007276:Injections, Intraventricular; D008297:Male; D009419:Nerve Tissue Proteins / Q000008:administration & dosage / Q000096:biosynthesis*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013345:Subarachnoid Hemorrhage / Q000378:metabolism* / Q000517:prevention & control*; D051176:beta Catenin / Q000096:biosynthesis*
chemical_list: C495268:Ctnnb1 protein, rat; D005136:Eye Proteins; D051157:Frizzled Receptors; C498582:Fzd4 protein, rat; C081848:NDP protein, human; D009419:Nerve Tissue Proteins; D051176:beta Catenin
keywords: Frizzled-4 protein; Norrin; blood–brain barrier; subarachnoid hemorrhage