title: Complex pattern of interaction between in utero hypoxia-ischemia and intra-amniotic inflammation disrupts brain development and motor function.
abstract: BACKGROUND
  Infants born preterm commonly suffer from a combination of hypoxia-ischemia (HI) and infectious perinatal inflammatory insults that lead to cerebral palsy, cognitive delay, behavioral issues and epilepsy. Using a novel rat model of combined late gestation HI and lipopolysaccharide (LPS)-induced inflammation, we tested our hypothesis that inflammation from HI and LPS differentially affects gliosis, white matter development and motor impairment during the first postnatal month.
  
  
  METHODS
  Pregnant rats underwent laparotomy on embryonic day 18 and transient systemic HI (TSHI) and/or intra-amniotic LPS injection. Shams received laparotomy and anesthesia only. Pups were born at term. Immunohistochemistry with stereological estimates was performed to assess regional glial loads, and western blots were performed for protein expression. Erythropoietin ligand and receptor levels were quantified using quantitative PCR. Digigait analysis detected gait deficits. Statistical analysis was performed with one-way analysis of variance and post-hoc Bonferonni correction.
  
  
  RESULTS
  Microglial and astroglial immunolabeling are elevated in TSHI + LPS fimbria at postnatal day 2 compared to sham (both P < 0.03). At postnatal day 15, myelin basic protein expression is reduced by 31% in TSHI + LPS pups compared to shams (P < 0.05). By postnatal day 28, white matter injury shifts from the acute injury pattern to a chronic injury pattern in TSHI pups only. Both myelin basic protein expression (P < 0.01) and the phosphoneurofilament/neurofilament ratio, a marker of axonal dysfunction, are reduced in postnatal day 28 TSHI pups (P < 0.001). Erythropoietin ligand to receptor ratios differ between brains exposed to TSHI and LPS. Gait analyses reveal that all groups (TSHI, LPS and TSHI + LPS) are ataxic with deficits in stride, paw placement, gait consistency and coordination (all P < 0.001).
  
  
  CONCLUSIONS
  Prenatal TSHI and TSHI + LPS lead to different patterns of injury with respect to myelination, axon integrity and gait deficits. Dual injury leads to acute alterations in glial response and cellular inflammation, while TSHI alone causes more prominent chronic white matter and axonal injury. Both injuries cause significant gait deficits. Further study will contribute to stratification of injury mechanisms in preterm infants, and guide the use of promising therapeutic interventions.
authors.forename: Lauren L
authors.initials: LL
authors.lastname: Jantzie
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Corbett
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Berglass
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Firl
authors.forename: Julian
authors.initials: J
authors.lastname: Flores
authors.forename: Rebekah
authors.initials: R
authors.lastname: Mannix
authors.affiliation: Departments of Neurology and Neurosurgery, F,M, Kirby Center for Neurobiology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA. Shenandoah.Robinson@childrens.harvard.edu.
authors.forename: Shenandoah
authors.initials: S
authors.lastname: Robinson
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000473:pathology; D001921:Brain / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D004622:Embryo, Mammalian; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology* / Q000503:physiopathology; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology*; D056784:Leukoencephalopathies / Q000209:etiology; D008070:Lipopolysaccharides / Q000633:toxicity; D008840:Microfilament Proteins / Q000378:metabolism; D004676:Myelin Basic Protein / Q000378:metabolism; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000378:metabolism
chemical_list: C100745:Aif1 protein, rat; D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D008070:Lipopolysaccharides; C436006:Mbp protein, rat; D008840:Microfilament Proteins; D004676:Myelin Basic Protein; D017467:Receptors, Erythropoietin; D004921:Erythropoietin
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