| Objective To investigate the expression of Hesl in adult mouse brain and the cell types of Hesl positive cells; and futher study the expression changes of Hesl in hippocampus of adult mouse with different degrees of traumatic brain injury (TBI). Through these studies clarify the expression of Hesl in adult mouse brain which is highly expressed in mouse embryonic nervous system; and preliminarilly discuss the relationship between neurogenesis and the repair of traumatic brain injury hoping to be able to promote TBI treatment.Methods Totally 66 adult male C57BL/6 mice and a C57BL/6 pregnant mouse were used.66 mice were randomly divided into immunohistochemical study group (n= 12) and TBI study group (n= 50). The fetal mice in pregnant mouse were used as the positive control group of immunohistochemical study group. Immunohistochemical study group was randomly divided into two groups:single staining group (n= 6) and double staining group (n= 6). For the single staining group, Hesl single staining was carried out to detect the expression of Hesl in adult mouse brain. For the double staining group, (Hesl+NeuN), (Hesl+GFAP) and (Hesl+Brdu) double staining were carried out to observe the cell types of Hesl positive cells in hippocampus. TBI group was randomly divided into mTBI study group (n= 39) and sTBI study group (n= 15). The mTBI study group was further divided into mTBI group (n= 21) and its control group (n= 18). The sTBI study group was further divided into sTBI group (n=9) and its control group (n= 6). The mild injured group and severe injured group were respectively subjected to lateral fluid percussion (LFP) injury of 1.3±0.1 ATM and 2.4±0.1ATM. Their control groups were subjected to the same surgical procedure without receiving fluid pulse.24 hours post injury,3 mice each from the two injury groups were sacrificed and subjected to HE staining to prove the traumatic model was successful. At different time points post injury,6 randomly selected mice were sacrificed from every group for Real Time PCR or Western blotting assay to observe the expression level of Hes1 in hippocampus.Results①Including olfactory bulb, cerebral cortex, hippocampus, deep brain nuclei, brainstem, cerebellum and other parts, Hesl was expressed in all the observed anatomical site.②Brdu positive cells nearly all expressed Hesl, NeuN positive cells all expressed Hesl, whereas GFAP positive cells did not express Hesl completely. The expression and distribution trends of Hesl in hippocampus were almost exactly the same as that of NeuN.③The results of mild traumatic brain injury group showed that compared with the corresponding control group, the expression of Hesl mRNA in traumatic lateral hippocampus on day 1 (P<0.05), day 3 (P< 0.001) and day 7 (P<0.001) post traumatic brain injury were significantly higher; meanwhile, the expression of Hesl on day 3 was a peak, and it was significantly higher (P<0.01) than that on day 1 and day 7.④The results of severe traumatic brain injury group showed that compared with the corresponding control group, the expression of Hesl protein in traumatic lateral hippocampus was significantly decreased (P<0.01) 3 days post traumatic brain injury.Conclusion①Hesl was expressed in all the observed anatomical site and The expression and distribution trends of Hesl in hippocampus were almost exactly the same as that of NeuN.②Hesl was expressed in newborn cells and mature neurons, but didn't expressed in astrocytes.③The expression of Hesl in traumatic lateral hippocampus post traumatic brain injury was increased on the first day, reached a peak on day 3, and declined on day 7 but still higher than that on day 1. And the expression of Hesl protein in traumatic lateral hippocampus on day 3 post traumatic brain injury was significantly decreased. So we can conclude that, when suffered from mild traumatic brain injury, the expression of Hesl in adult mouse hippocampus was increased at early stage, so as to promote the divison and proliferation of neural stem cells, the expression reached a peak on day 3 and declined on day 7 so as to promote the differentiation and maturation of neural stem cell; but when suffered from severe traumatic brain injury, the expression of Hesl in adult mouse hippocampus declined, and that resulted in the deficiencies of the divison and proliferation of neural stem cells, therefore, it was relatively more difficult to repair. |
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