title: Hypoxic preconditioning differentially affects GABAergic and glutamatergic neuronal cells in the injured cerebellum of the neonatal rat.
abstract: In this study we examined cerebellar alterations in a neonatal rat model of hypoxic-ischemic brain injury with or without hypoxic preconditioning (Pc). Between postnatal days 7 and 15, the cerebellum is still undergoing intense cellular proliferation, differentiation and migration, dendritogenesis and synaptogenesis. The expression of glutamate decarboxylase 1 (GAD67) and the differentiation factor NeuroD1 were examined as markers of Purkinje and granule cells, respectively. We applied quantitative immunohistochemistry to sagittal cerebellar slices, and Western blot analysis of whole cerebella obtained from control (C) rats and rats submitted to Pc, hypoxia-ischemia (L) and a combination of both treatments (PcL). We found that either hypoxia-ischemia or Pc perturbed the granule cells in the posterior lobes, affecting their migration and final placement in the internal granular layer. These effects were partially attenuated when the Pc was delivered prior to the hypoxia-ischemia. Interestingly, whole nuclear NeuroD1 levels in Pc animals were comparable to those in the C rats. However, a subset of Purkinje cells that were severely affected by the hypoxic-ischemic insult--showing signs of neuronal distress at the levels of the nucleus, cytoplasm and dendritic arborization--were not protected by Pc. A monoclonal antibody specific for GAD67 revealed a three-band pattern in cytoplasmic extracts from whole P15 cerebella. A ∼110 kDa band, interpreted as a potential homodimer of a truncated form of GAD67, was reduced in Pc and L groups while its levels were close to the control animals in PcL rats. Additionally we demonstrated differential glial responses depending on the treatment, including astrogliosis in hypoxiated cerebella and a selective effect of hypoxia-ischemia on the vimentin-immunolabeled intermediate filaments of the Bergmann glia. Thus, while both glutamatergic and GABAergic cerebellar neurons are compromised by the hypoxic-ischemic insult, the former are protected by a preconditioning hypoxia while the latter are not.
authors.affiliation: Laboratory of Neurobiology: Chronobiology Section, Institute of Histology and Embryology of Mendoza (IHEM), School of Medicine, National University of Cuyo, Mendoza, National Scientific and Technical Research Council (CONICET), National Agency for Scientific and Technological Promotion (ANPCyT), Mendoza, Argentina.
authors.forename: Sergio G
authors.initials: SG
authors.lastname: Benitez
authors.affiliation: Laboratory of Neurobiology: Chronobiology Section, Institute of Histology and Embryology of Mendoza (IHEM), School of Medicine, National University of Cuyo, Mendoza, National Scientific and Technical Research Council (CONICET), National Agency for Scientific and Technological Promotion (ANPCyT), Mendoza, Argentina.
authors.forename: Analía E
authors.initials: AE
authors.lastname: Castro
authors.affiliation: Traumatic and Toxic Lesions in the Nervous System Section, Institute of Histology and Embryology of Mendoza (IHEM), School of Medicine, National University of Cuyo, Mendoza, National Scientific and Technical Research Council (CONICET), National Agency for Scientific and Technological Promotion (ANPCyT), Mendoza, Argentina.
authors.forename: Sean I
authors.initials: SI
authors.lastname: Patterson
authors.affiliation: Laboratory of Neurobiology: Chronobiology Section, Institute of Histology and Embryology of Mendoza (IHEM), School of Medicine, National University of Cuyo, Mendoza, National Scientific and Technical Research Council (CONICET), National Agency for Scientific and Technological Promotion (ANPCyT), Mendoza, Argentina.
authors.forename: Estela M
authors.initials: EM
authors.lastname: Muñoz
authors.affiliation: Neonatal Brain Development Section, Institute of Histology and Embryology of Mendoza (IHEM), School of Medicine, National University of Cuyo, Mendoza, National Scientific and Technical Research Council (CONICET), National Agency for Scientific and Technological Promotion (ANPCyT), Mendoza, Argentina.
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Seltzer
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D000911:Antibodies, Monoclonal / Q000276:immunology; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis*; D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation; D002465:Cell Movement; D049109:Cell Proliferation; D002531:Cerebellum / Q000293:injuries / Q000473:pathology; D005260:Female; D059330:GABAergic Neurons / Q000473:pathology; D005968:Glutamate Decarboxylase / Q000096:biosynthesis* / Q000276:immunology; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology*; D019194:Ischemic Preconditioning; D008297:Male; D009457:Neuroglia / Q000473:pathology; D011689:Purkinje Cells / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY
chemical_list: D000911:Antibodies, Monoclonal; D051792:Basic Helix-Loop-Helix Proteins; D015415:Biomarkers; D005968:Glutamate Decarboxylase; C490555:Neurod1 protein, rat; C402565:glutamate decarboxylase 1