Neurotoxicity Research

, Volume 15, Issue 4, pp 348–358 | Cite as

Neuronal and Glial Alterations Due to Focal Cortical Hypoxia Induced by Direct Cobalt Chloride (CoCl2) Brain Injection

  • Laura Caltana
  • Amalia Merelli
  • Alberto Lazarowski
  • Alicia Brusco
Article

Abstract

Ischemic brain injury is a dynamic process that involves oxidative stress, inflammation, and cell death, as well as activation of endogenous adaptive and regenerative mechanisms depending on activation of transcription factors such as hypoxia inducible factor 1-alpha (HIF-1α). Because CoCl2 activates HIF-1α, we described a new focal-hypoxia model by direct intracerebral CoCl2 injection. Adult male Wistar rats were intracerebrally injected with CoCl2 (2 μl–50 mM), in frontoparietal cortex of right hemisphere, and saline (2 μl) in the contralateral hemisphere. In slides of fixed brains at 1, 6, 9, 24 h or 5 day after treatment, TTC, histochemistry (toluidine blue, Hoescht-33342, TUNEL), immunostaining (HIF-1α, GFAP), Lycopersicon esculentum lectin staining, and electron microscopy (EM) were performed. Immediately after 1 h post CoCl2 injection, HIF-1α stabilization and neuronal nuclear shrinkage and cromathin condensation were observed by immunostaining and EM, respectively. Neuronal apoptotic nuclear morphology and GFAP immunoreactivity and lectin maximal reactivity were detected during 6–9 h. Ultrastructural alterations of morphology included edematous perinuclear cytoplasm, organelles and endoplasmic reticulum (RE) enlargement, mitochondrial swelling with increased matrix density, and deposits of electron-dense material. Neurons showed particular nuclear indentations. Astrocytes and oligodendrocytes presented alterations in both nuclei and RE with dilated lumen and altered mitochondrias, and all these ultrastructural changes became detectable at day 5. CoCl2 cortical injection mimics focal brain ischemia, inducing neuronal death and glial activation. This model brings the opportunity to develop focal ischemia in selected brain areas to study their functional consequences and potential pharmacological therapies for in vivo models of stroke.

Keywords

Focal hypoxia Astrocytes Neuronal death CoCl2 

Notes

Acknowledgments

We thank Mrs. Emerita Jorge Vilela de Bianchieri for her expert technical assistance with the EM studies and Dr. A. Ramos for his help in the interpretation of the results. Sources of Funding: Supported by grants UBACYT M-072, UBACYT M-004, CONICET PIP5034 (to A.B.).

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Laura Caltana
    • 1
  • Amalia Merelli
    • 1
    • 2
  • Alberto Lazarowski
    • 1
    • 2
  • Alicia Brusco
    • 1
  1. 1.Instituto de Biología Celular y Neurociencias “Prof. E. De Robertis”, Facultad de MedicinaUniversidad de Buenos AiresBuenos AiresArgentina
  2. 2.Instituto de Investigaciones en Fisiopatología y Bioquímica Clínica (INFIBIOC)Facultad de Farmacia y Bioquímica (UBA)Buenos AiresArgentina

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