title: Methyl-isobutyl amiloride reduces brain Lac/NAA, cell death and microglial activation in a perinatal asphyxia model.
abstract: Na⁺/H⁺ exchanger (NHE) blockade attenuates the detrimental consequences of ischaemia and reperfusion in myocardium and brain in adult and neonatal animal studies. Our aim was to use magnetic resonance spectroscopy (MRS) biomarkers and immunohistochemistry to investigate the cerebral effects of the NHE inhibitor, methyl isobutyl amiloride (MIA) given after severe perinatal asphyxia in the piglet. Eighteen male piglets (aged < 24 h) underwent transient global cerebral hypoxia-ischaemia and were randomized to (i) saline placebo; or (ii) 3 mg/kg intravenous MIA administered 10 min post-insult and 8 hourly thereafter. Serial phosphorus-31 (³¹P) and proton (¹H) MRS data were acquired before, during and up to 48 h after hypoxia-ischaemia and metabolite-ratio time-series Area under the Curve (AUC) calculated. At 48 h, histological and immunohistochemical assessments quantified regional tissue injury. MIA decreased thalamic lactate/N-acetylaspartate and lactate/creatine AUCs (both p < 0.05) compared with placebo. Correlating with improved cerebral energy metabolism, transferase mediated biotinylated d-UTP nick end-labelling (TUNEL) positive cell density was reduced in the MIA group in cerebral cortex, thalamus and white matter (all p < 0.05) and caspase 3 immunoreactive cells were reduced in pyriform cortex and caudate nucleus (both p < 0.05). Microglial activation was reduced in pyriform and midtemporal cortex (both p < 0.05). Treatment with MIA starting 10 min after hypoxia-ischaemia was neuroprotective in this perinatal asphyxia model.
authors.affiliation: Institute for Women's Health, University College London, London, UK. n.robertson@ucl.ac.uk
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Robertson
authors.forename: Takenori
authors.initials: T
authors.lastname: Kato
authors.forename: Alan
authors.initials: A
authors.lastname: Bainbridge
authors.forename: Manigandan
authors.initials: M
authors.lastname: Chandrasekaran
authors.forename: Osuke
authors.initials: O
authors.lastname: Iwata
authors.forename: Andrew
authors.initials: A
authors.lastname: Kapetanakis
authors.forename: Stuart
authors.initials: S
authors.lastname: Faulkner
authors.forename: Jeanie
authors.initials: J
authors.lastname: Cheong
authors.forename: Sachiko
authors.initials: S
authors.lastname: Iwata
authors.forename: Mariya
authors.initials: M
authors.lastname: Hristova
authors.forename: Ernest
authors.initials: E
authors.lastname: Cady
authors.forename: Gennadij
authors.initials: G
authors.lastname: Raivich
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001237:Asphyxia / Q000188:drug therapy* / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004195:Disease Models, Animal; D020925:Hypoxia-Ischemia, Brain / Q000188:drug therapy* / Q000378:metabolism; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D019344:Lactic Acid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D013552:Swine
chemical_list: D018696:Neuroprotective Agents; D001224:Aspartic Acid; D019344:Lactic Acid; D000584:Amiloride; C056369:5-(N-methyl-N-isobutyl)amiloride; C000179:N-acetylaspartate