Alpha tocopherol treatment reduces the expression of Nogo-A and NgR in rat brain after traumatic brain injury

作者:Yang, Jinfu; Han, Yongfeng*; Ye, Weiwei; Liu, Feng; Zhuang, Kai; Wu, Guangyong
来源:Journal of Surgical Research, 2013, 182(2): E69-E77.
DOI:10.1016/j.jss.2012.11.010

摘要

Background: Neurite outgrowth inhibitor-A (Nogo-A), myelin-associated glycoprotein, and oligodendrocyte myelin glycoprotein are three myelin-associated proteins that act as inhibitors to central nervous system regeneration. Neurite outgrowth inhibitor-A imposes the strongest effect on inhibiting axonal regeneration after traumatic brain injury. Alphatocopherol, a member of the vitamin E family, is recognized as an active antioxidative substance. Its use has not been well studied in brain injury research, especially in axonal regeneration research. Methods: We obtained 99 intact adult male Sprague-Dawley rats (200-250 g) from the Experimental Animal Center of Central South University. We used the modified method of Freeney to generate moderate brain injury in the rats. We injected 600 mg/kg alpha-tocopherol intraperitoneally daily as traumatic brain injury (TBI) treatment. Then, we performed behavioral tests in the corresponding time point, examined brain tissues after hematoxylin-eosin staining to identify changes in cell morphology, and performed immunohistochemical staining and quantitative real-time polymerase chain reaction to detect the expression of NoGo and Nogo receptor (NgR) in brain tissue. Results: For the Neurological Severity Scores of rats, there were obvious differences among the three groups at the corresponding time points. Standard hematoxylin-eosin staining showed that the brain structure of a sham-operated group of rats was clear, uniform, and compact. A TBI group exhibited hemorrhage, edema, inflammatory cell infiltration, condensed nuclei, and necrosis. We also saw glial cells and fibrous tissue proliferation. The alpha-tocopherol-treated TBI group had similar but less severe changes than the TBI group. Expression of Nogo-A and NgR increased after TBI compared with the sham-operated group. However, Nogo-A and NgR expression was significantly lower in the alpha-tocopherol-treated TBI group compared with the TBI group. Similarly, results showed that functional neurological deficits among rats in the alpha-tocopherol-treated TBI group were less pronounced than in the TBI group (model group). Conclusions: Our data demonstrate that alpha-tocopherol-treated rats had reduced microscopic evidence of brain damage. Alpha-tocopherol reduced Nogo-A and NgR expression in brain tissue after traumatic brain injury and promoted nerve regeneration. Alpha-tocopherol treatment of TBI rats had a neuroprotective role in their recovery.