Expression of p75NTR in cerebrospinal fluid-contacting neurons of rats with spinal cord injury

English Keywords:Spinal cord injury  Cerebrospinal fluid-contacting neurons  P75 neurotrophin receptor

English Abstract:

  【Abstract】 Objectives: To investigate the changes in expression of p75 neurotrophin receptor(p75NTR) in cerebrospinal fluid-contacting neurons(CSF-CNs) of rats with spinal cord injury. Methods: Thirty-six female adult Sprague-Dawley(SD) rats were randomly divided into normal control group(n=6), sham operation group(n=6) and spinal cord injury group(n=24). Allen′s weight-drop method(10g×3cm) was adopted to induce acute spinal cord injury at T10 segment． Rats were sacrificed at 3 days and 1, 2 and 4 weeks respectively after injury． All animals were evaluated on the hind limb behavior with BBB locomotor score. HE staining was performed at different time points. Intracerebroventricular injection of cholera toxin subunit B with horse radish peroxidase(CB-HRP) was performed to specifically mark CSF-CNs at 48h before animals were sacrificed at each time point． After rats were sacrificed, double immunofluorescence staining was performed at spinal site within 10mm away from the injury to detect the expression of p75NTR in CSF-CNs. Software Image-Pro Plus was used to count the positive neurons. Results: The BBB score of sham operation group at each time point was 21.0±0. The BBB score of spinal cord injury group at each time point of 3 days and 1, 2 and 4 weeks after injury was 3.20±0.81, 10.73±1.02, 12.48±1.86, 13.29±1.93 respectively. There were significant differences between the two groups at different time points(P<0.05). HE staining showed that in normal control group and sham operation group, the structure of spinal cord was complete and the cell morphology was normal; in spinal cord injury group, disorder of spinal cord tissue, degeneration and necrosis of nerve cells, proliferation of glial cells, formation of glial scar and spinal cord porosis were found. Double immunofluorescence staining showed that there were a few CB-HRP/p75 double positive cells in normal control group and sham operation group. The number of CB-HRP/p75 double positive cells in these two groups was respectively 5.16±0.55, 4.31±0.61. There was no significant difference between the two groups(P>0.05). The number of CB-HRP/p75 double positive cells in spinal cord injury group at 3 days and 1, 2 and 4 weeks after injury was 13.35±1.53, 21.68±2.15, 16.26±2.09 respectively. Compared with normal control group and sham operation group, the difference was statistically significant(P<0.05). At 4 weeks after injury, the number of CB-HRP/p75 double positive cells was 4.83±0.73. Compared with normal control group and sham operation group, the difference was not statistically significant(P>0.05). Conclusions: p75NTR is expressed in CSF-CNs of the normal rats and its expression increases after acute spinal cord injury． CSF-CNs might participate in the repair of spinal cord injury via p75NTR．