Abstract
Background: The forebrain subventricular zone (SVZ) contains oligodendroglial (OL) stem cells. Although some studies suggest acute loss of SVZ OL precursors after hypoxic-ischemic (HI) neonatal brain injury, recovery of myelin basic protein (MBP) immunostaining in the white matter 2 weeks after HI raises the possibility that OL stem cells in the SVZ might proliferate to repopulate injured white matter. As an alternative to using the HI model to study the SVZ response to neonatal brain injury, we developed a model of neonatal brain injury that focuses on a unique mechanism of increased vulnerability of immature OLs, AMPA-receptor mediated excitotoxicity. Intracerebroventricular (icv) injection of the synthetic glutamate analog AMPA in seven-day-old (P7) rats caused reduced expression of two OL-specific genes, proteolipid protein and MBP. We hypothesized that the immature SVZ would respond to injury with cellular proliferation; we used the AMPA icv injection model to test this.
Methods: P7 rats received either left (n=4) or right (n=3) stereotaxic icv injections of S-AMPA, 2.5 nmol in 5 μl sterile water (pH adjusted to 7.2). Controls included right icv injections of sterile PBS 5 μl (n=3) and non-injected littermates (n=3). 4h prior to sacrifice, all animals received an intraperitoneal injection of bromodeoxyuridine (BrdU), 100 mg/kg, to label cells entering the cell cycle. On P14, animals were perfused with 4% paraformaldehyde, cryoprotected in sucrose and sectioned serially at 60 μm. A series of every fourth section was stained immunohistochemically for the novel proliferation marker Ki67. A second series was immunolabeled with anti-BrdU. Bilateral SVZ was outlined and Ki67+ or BrdU+ cells were counted stereologically using the Optical Disector method.
Results: The density of Ki67+ cells was increased in ipsilateral SVZ of AMPA injected rats relative to PBS-injected and normal controls (Mean (±SD) density/mm3 AMPA ipsilateral 111,261±37,197*†, AMPA contralateral 93,698±32,248†, PBS 63,572±18,793, Normal 36,697±15,169; p<0.05 ANOVA with Fisher LSD post-hoc test, compared to * PBS and † Normal). The number of Ki67+ cells/SVZ was increased both ipsi- and contralateral to the icv injection, compared to normals, but Ki67+ cell number was also increased to a lesser, but not significant extent in PBS controls.
Conclusion: This preliminary study suggests that there is a proliferative response in the immature SVZ in response to an AMPA receptor-mediated excitotoxic stimulus.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Barks, J., Xu, G., Ong, J. et al. 18 Subventricular Zone Proliferation After Ampa Receptor-Mediated Neonatal Brain Injury. Pediatr Res 56, 467 (2004). https://doi.org/10.1203/00006450-200409000-00041
Issue Date:
DOI: https://doi.org/10.1203/00006450-200409000-00041