IngentaConnect Temporal profile of neural stem cell proliferation in the subvent...

Authors: Iwai, Masanori¹; Ikeda, Tomoaki²; Hayashi, Takeshi¹; Sato, Keiko¹; Nagata, Tetsuya¹; Nagano, Isao¹; Shoji, Mikio¹; Ikenoue, Tsuyomu²; Abe, Koji¹

Source: Neurological Research, Volume 28, Number 4, June 2006 , pp. 461-468(8)

Publisher: Maney Publishing

Abstract:

Objectives: Ischemia/hypoxia (I/H) causes severe neonatal brain injury, such as periventricular leukomaracia and hypoxic/ischemic encephalopathy. Neural stem cell research could lead to a treatment for such disorders. In order to elucidate the dynamic changes in neural stem cells in the neonatal brain after I/H, we investigated the proliferation of new cells in the subventricular zone (SVZ).

Methods: Seven-day-old Wister rats were subjected to ligation of the left carotid artery followed by 2 hours of hypoxic stress (8% O₂ and 92% N₂, at 33°C). In order to elucidate the dynamic change of neural stem cells in the SVZ, single bromodeoxyuridine (BrdU; 50 mg/kg) was administered 2 hours before death 1, 7, 14 and 21 days after I/H. Immunohistochemical and immunofluorescent studies for BrdU and doublecortin (DCX) were carried out. As a control, a group of rats was subjected to sham surgery (incision of skin, but no ligation of the carotid artery) and no I/H.

Results: The numbers of BrdU-labeled cells in the SVZ, for both the ipsilateral side and the contralateral side of the I/H brain, were twice the level of the control at 7 days after I/H, but the numbers for both sides returned to the control level at 21 days. In the ipsilateral side of the I/H brain, the number of BrdU-labeled cells in the SVZb (lining the upper wall of lateral ventricle) was 4-fold at 7 days and 15-fold at 21 days after I/H compared with the control level. This chronological pattern is very similar to the pattern for I/H results of the posterior periventricle (pPV). DCX appeared in most BrdU-labeled cells in the SVZb and pPV.

Discussion: These findings indicate that I/H enhances neural stem cell proliferation in the SVZ, and some newborn cells migrate as neural precursors to the SVZb and pPV after I/H in the neonatal rat brain.

Keywords: ISCHEMIA/HYPOXIA; NEONATAL RAT BRAIN; NEURAL STEM CELLS; PROLIFERATION; SUBVENTRICULAR ZONE

Document Type: Research article

DOI: 10.1179/016164105X49283

Affiliations: 1: Department of Neurology, Graduate School of Medicine and Dentistry, Okayama University, Okayama, 700-8558, Japan 2: Department of Obstetrics and Gynecology, Miyazaki Medical College, Miyazaki, 889-1601, Japan

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Temporal profile of neural stem cell proliferation in the subventricular zone after ischemia/hypoxia in the neonatal rat brain