Abstract: Objective To investigate the effect of traumatic brain injury on the expressions of glial cell line-derived neurotrophic factor (GDNF) and its receptors in brain stem of rats.Methods 55 male Sprague-Dawley rats were divided into the normal control group, sham surgery group and injury groups. The rats of injury groups were subjected to Marmarou's closed traumatic brain injury and then were subdivided into 1 h, 2 h, 4 h, 8 h, 12 h, 24 h, 48 h, 72 h and 5 d groups according to the time elapsed after injury. The expressions of GDNF and its receptors (GFRα-1 and Ret) were tested with immunohistochemistry.Results Mild expressions of GDNF and its receptors were observed in brain stem of rats in the normal control group and sham surgery group. The number of GDNF positive neurons reached the peak level at 2 h in brain stem after injury, and that of GFRα-1 and Ret positive neurons reached the peak level at 4 h after injury.Conclusion The expressions of GDNF and its receptors increase significantly at the early time in brain stem of rats after injury. The similar temporal patterns of expressions of GDNF and its receptors are observed in brain stem after brain injury.

Key words: traumatic brain injury, glial cell line-derived neurotrophic factor (GDNF), receptor, brain stem