Effects of basic fibroblast growth factor on neurogenesis in the subventricular zone of 3-day-old rats following brain ischemia

Abstract

Objective To investigate the effects of exogenous basic fibroblast growth factor (bFGF) on neurogenesis in the subventricular zone (SVZ) of 3-day-old rats following brain ischemia. Methods Seventy-two brain ischemia models of 3-day-old SD rats were established by ligating bilateral common carotid artery. The models were divided into treatment group with 10 ng/g bFGF injection and the control group with saline. Another 36 rats underwent operation without ischemia served as sham-operate group. Proliferating cells were labeled by bromodeoxyuridine (BrdU) through intraperitoneal injection in a cumulative protocol. Rats were killed at 4, 7 and 14 days after ischemic injury. Immunofluoreseence assays, Western blot and real-time PCR were used to observe cellular changes, including the protein expression of nestin, Tuj1, glial fibrillary acidic protein (GFAP) and NG2, and also their mRNA expression in SVZ, respectively. Results (1) Immunofluorescence assay showed that the number of BrdU1/nestin+ cells in SVZ of treatment group was the highest at day 7 after operation [(48. 7±5.9)/field], higher than those in control [(32. 2±3. 1)/field] and sham-operate group [(17.3±1.6)/field] (P<0. 01). The number of BrdU+/Tuj1+ cells, BrdU+/ GFAP+ cells and BrdU+/NG2+ cells in SVZ of treatment group were highest at day 14 after brain ischemia [(92.6±9.7) ,(58.2±6.1) ,(57.3±5.4)/field, respectively], higher than those in control [(65. 8±7. 1), (42. 1 ± 4. 4), (37.8 ± 3. 2)/field, respectively] and sham-operate group [(35.3± 3. 1), (33.6± 3.4), (22.4 ± 2. 1)/field, respectively] (P<0. 01 ). (2) Western blot and real-time PCR analysis found that the expressions of nestin protein and mRNA peaked on day 7, and the expressions of Tuj1, GFAP, and NG2 protein and mRNA peaked on day 14 after operation. The highest expression of nestin, Tuj1, GFAP, and NG2 protein and mRNA were detected in the treatment group. Conclusions bFGF not only increases the proliferation of neural stem cells in SVZ, but also stimulates the differentiation of these cells into neurons, astrocytes, and oligodendroeytes after ischemic injury, bFGF helps repair neonatal ischemic brain injury in rats. Key words: Fibroblast growth factor 2; Brain ischemia; Nerve regeneration; Rats