Dynamic changes of Notch1 protein expression in the subventricular zone after traumatic cerebral injury of the rats

Objective To observe the dynamic changes of Notch1 protein expression in the subventricular zone (SVZ) after traumatic cerebral injury (TBI) in rats, and to explore the correlation between Notch signaling pathway and neural stem cells (NSCs) proliferation after TBI. Methods Ninety-six SD rats were randomly divided into sham-operated group (only opening the scalp and skull window, n=16), control group (without any treatment, n=16) and experimental group (establishing medium-sized TBI models with Feeney's free fall method, n=64); rats in the experimental group were divided into 4 sub groups according to the execution times (one, three, 7 and 14 d after TBI, n=16). Immunofluorescence staining was performed to detect the Notch1/nestin labeled cell expressions in SVZ of rats, and Notch1 protein expression was detected by Western blotting. Results Immunofluorescence results showed that the Notch1/nestin double staining positive cells in the right SVZ brain tissues of the experimental group on the first day of TBI had peak level, which was 2-3 times of the control group; and then, it gradually declined and basically returned to normal on 14th day of TBI; the differences between the 4 subgroups were statistically different (P<0.05). The positive cell counts in the subgroups of first, third, and 7th d after TBI were statistically different as compared with those in the control group and sham operated group (P<0.05). Western blotting results indicated that there was no significant difference in the Notch1 protein expression between control group and sham operated group; Notch1 protein expression in SVZ of the experimental group had peak level on the first day of TBI, gradual decline was noted after that, and normal level was noted on the 14th d of TBI. Conclusion TBI can activate the Notch1 protein expression, which induces the opening of Notch signaling pathway so as to affect the regulation of NSCs proliferation. Key words: Traumatic cerebral injury; Notch1 protein; Notch signaling pathway; Neural stem cell