[Neurogenesis in the subventricular zone of neonatal rats after ischemic brain injury]

To study the proliferation and differentiation of neural stem cells in the subventricular zone (SVZ) in neonatal rats after bilateral common arteries occlusion.

Ninety-six 3-day-old Sparuge-Dawley rats were randomly divided into two groups: ischemia and control. Rats in the ischemia group were subjected to bilateral common arteries occlusion and the rats in the control group were sham-operated. All rats were administrated with 5-bromodeoxyuridine (BrdU) (50 mg/kg) via intraperitoneal injection. Rats were sacrificed and their brains were removed 1, 4, 7, 10, 14 and 35 days after ischemia. Using brain paraffin sections and immunofluorescence assays, the number of newborn cells in the SVZ was counted. Newborn neural stem cells and oligodendrocytes in the SVZ were observed, and then double marked with BrdU and nestin or osmium tetroxide (O4).

The number of BrdU+ cells (neural stem cells) in the SVZ in the ischemia group was greater than in the control group 4, 7, 10 and 14 days after ischemia, and reached a peak at 4 days after ischemia (253.1+/- 49.3 vs 133.5+/- 17.7; P< 0.01). By 35 days after ischemia, the number of BrdU+/O4+ cells (oligodendrocytes) in the corpus callosum (56.0+/- 7.2 vs 17.0+/- 6.4; P< 0.01), the septal nuclei (45.0+/- 11.9 vs 20.5+/- 5.0; P< 0.01), the striatum (34.5+/- 4.2 vs 14.5+/- 5.8; P< 0.01) and the olfactory bulb (46.5+/- 6.6 vs 23.5+/- 8.4; P< 0.01) in the ischemia group increased significantly as compared to the control group (P< 0.01).

Brain ischemia can activate the proliferation of neural stem cells in the SVZ and promote neural stem cells differentiation into oligodendrocytes. The immature brain may have the capacity for self-repair after ischemic brain injury.