Effects of Oestrogen on Ischemia-induced Neurogenesis in the Dentate Gyrus of Rats

To study the effects of oestrogen on ischemia?induced neurogenesis in the hippocampal dentate gyrus, thirty-two adult male rats were randomly divided into four groups:the control surgery group with oestrogen administration (SE), the control surgery group with normal saline administration (SN), the middle cerebral artery occlusion (MCAO) group with oestrogen administration (ME) and the MCAO group with normal saline administration (MN). The MCAO rats were occluded for 90 min by an intraluminal filament and then recirculated. After 1, 3, 12, 24 and 28 h of MCAO, the rats of the four groups were killed to investigate the infarct volume, apoptosis and neurogenesis. The cerebral infarct volume in the ME group was significantly smaller than that of the MN group (P<0.05). No significant cell loss was seen in the dentate gyrus. Cerebral ischemia led to increased neurogenesis, which is independent of cell death in the ipsilateral dentate gyrus (P<0.05). BrdU-positive cells in the ipsilateral dentate gyrus of the ME group were significantly increased when compared with those of the MN group(P<0.05). In the SE group, BrdU-positive cells in both the ipsilateral and contralateral dentate gyrus, were increased when compared with those of the SN group (P<0.05). We concluded that oestrogen plays an important role in neurogenesis, which is independent of ischemia-induced by MCAO in the hippocampal dentate gyrus of rats.

Keywords
Cerebral ischemia; Infarct volume; Neurogenesis; Oestrogen; Cell death; Dentate gyrus