| Objective:To observe the effects of different radioactivity of 125I seeds on the histomorphology of dorsal root ganglion and the surrounding tissues,pain behavious and movement by implanting radioactive seeds 125I around dorsal root ganglionMethods:The experiment were carried out using forty adult male Sprague-Dawley rats (220-250g), randomly assigned to four groups.the different radioactivity 1251 seeds were implanted around dorsal root ganglion,respectively named OmCi group (n=10),0.4mCi group(n=10),0.6 mCi group(n=10),0.8 mCi group(n=10). CT scan were used to check the seeds whether locating in 1cm range aroud dorsal root ganglion.if not in the range,the rat must be rejected.the two rats were killed at 14 and 60 days randomly to observe the histomorphology of L5 dorsal root ganglion and the surrounding tissues. The pain behavious and movement of every rat was observed before 2 and after 2-,7-,14-,30-and 60- day following the procedure.Results:1. the implantion of 125I seeds was successful around L5 DRG in 40 rats.(2 rats were rejected, then supplement in time), CT scan ensure exact position.2. the pain behavious test results:there were no significant differences for 0mCi group at every time point with regard to MWT and TWL.Compared to 0mCi group, MWT and TWL of 0.6,0.8mCi group were lower than OmCi group at 7,14day(P<0.05),0.4 mCi group were lower than 0 mCi group at 30d.at 60 day, the MWT of 0.8mCi group were signally higher than other groups(P<0.05). About TWL of 0.6,0.8mCi group were higher than 0,0.4mCi group(P<0.05). the CBS of all group had no signally change.3. the DRG under light microscppe:the cellular swelling of the OmCi group was moderate at 14 and 60 day. a small number of DRG cell at 14 day become hydropic degeneration,and loss of nissl bodies. While at 60 day,the cell edema was more severe, the nucleus was not in center and Karyopyknosis,fragmentation in the 0.4 mCi group.In the 0.6 mCi group,some cellular swelling and karyolysis were observed at 14 day, while a large of DRG cell became karyolysis and nuclear condensation at 60 day. In the 0.8 mCi group, karyolysis and nuclear condensation was observed at 14 day,mass DRG cell revealed karyolysis,nuclear condensation and degeneration at 60 day. The ratio of positive cells (the nucleus was not in center or Cytoplasmic was abnormal) and apoptosis rate was correlated positively to radioactive activity and duration of irradiation. were 73.80±2.38%,26.00±2.12% respectively at 60day in 0.8 mCi group.4. muscular tissue change under light microscppe:A:the muscular tissue near the seeds (5mm) In OmCi group,the size of muscle fiber were uniform, muscle gap widened slightly, a few inflammatory infiltrate at 14 day, at 60 day, muscle clearance was obvious, the connective tissue proliferated,muscle fiber were regularly arranged. a qualitatively greater amount of inflammatory cells and proliferated connective tissue were observed in 14 day of 0.4mCi group. At 60 day, Some myofiber became degeneration, swelling. In 0.6 mCi group, The muscle fiber's wither,connective tissue and capillaries remarkable hyperplasia can be seen at 14 day, then Muscle fiber became dissolving, Muscle membrane is not clear at 60d. In 0.8mCi group, dissolving muscle fiber and proliferated connective tissue were observed at 14 day, muscle fiber become disordered and dissolving at 60 day. B:the contralateral muscle tissue:In OmCi group,the size of muscle fiber were uniform, there were not proliferated connective tissue and inflammatory cell at 14 day, muscle gap widened slightly at 60 day. At 14 day,muscle clearance was obvious, the cellular swelling was moderate in 0.4,0.6,0.8 mCi group, muscle was uniform at 60 day.5.cauda equian change under light microscppe:In OmCi group, distribution of Nerve fiber is uniform,Myelin become thinner slightly. Compared to OmCi group distribution of the other groups were nonuniform,especially 0.8 mCi group at 14 day. at 60day, distribution of Nerve fiber were more uniform than at 14day. the axis cylinder and Nerve fiber of the 0.6mCi and 0.8mCi group was seen at 60 day. A few Myelin disintegrated spherical or oval shape, accompanying with vacuolar degeneration. Conclusion1.DRG can be injured after implanting radioactive 125I around DRG, mainly characterized by necrosis,the intensity of which were increased as radiological dose and duration increased.2. Damage to muscular tissue by radioactive 125I were observed, short distance can had a tremendous impact on the severity.3.Radioactive 125I have an effect on cauda equian, the intensity of which were increased as radiological dose and duration increased.4. threshold of 0.8mCi group's mechanical pain and thermo-pain reduced after implanting radioactive I25I, there was no influence on motor function at 60 day. |
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