The morphologic changes of dorsal root ganglion after lumbar nerve root being under chronic compression and inflammatory stimulation in rabbits / 中华物理医学与康复杂志

ABSTRACT

Objective To observe the morphologic changes of dorsal root ganglion in the lumbar region of rabbits after the nerve root was under chronic compression and inflammatory stimulation. Methods Twenty New Zealand rabbits were recruited for this study, of which 5 served as the control (control group), and the rest were randomized into 3 experimental subgroups 10d group, 30d group, 90d group, respectively. The autologous nucleus pulposus from the tails (about 5mg) was put into the silastic tube (inner meter of 1.5mm, external diameter 2.5mm and length 12mm), which was inserted into the left L 7 intervertebral foramen to compress the lumbar nerve root. Sham operation was performed with the rabbits in the control group. The nerve root and the dorsal root ganglia were harvested and processed and observed with light microscope and electron microscope after 10d, 30d, 90d, respectively. Results In the 10d group, obvious hyperemia, edema and infiltration of inflammatory cells in the interspace of the intima of the dorsal root ganglia (DRG) could be observed. Pyknosis, degeneration and necrosis were also found in some of the nerve cells. Electron microscopic observation showed that the number of the rough endoplasmic reticulum and mitochondrion decreased, ribosome exfoliated, mitochondrion swelled. In 30d group, typical degeneration and necrosis became more obvious. Electron microscope showed that the number of lysosome and smooth endoplasmic reticulum increased, mitochondrion swelled and its cristae disappeared, nuclei concentrated and deviated. In 90d group, significant proliferation of fibrocyte could be observed. At the same time, dura mater and arachnoid of spinal cord around the nerve root were notably thickened, and became fibrogenesis. Electron microscope also showed the increment of the lysosome and smooth endoplasmic reticulum, the swelling of mitochondrion, the loss of its cristae and the concentration of the nucleolus in the central part of the nuclei. No significant changes were found in the control group. Conclusion Pathological changes of neural degeneration such as edema, inflammatory infiltration could be observed in dorsal root ganglion after the nerve root was under chronic compression and stimulation by autologous nucleus pulposus.