椎间孔植入125I粒子对大鼠背根神经节神经元形态学及痛行为学的影响

Effects of implantation of iodine-125 seeds in the intervertebrai foramina on histological changes in dorsal root ganglion and pain threshold in rats

目的评价椎间孔植入125I粒子对大鼠背根神经节（DRG）神经元形态学及痛行为学的影响。方法成年雄性SD大鼠36只，6月龄，体重220～250g，采用随机数字表法，将其随机分为3组（n=12）：假手术组（A组）和低、高活度125I粒子组（B组和C组）。3组分别于L4,5和L5,6椎间孔植入1粒放射活度为0、0．4、0．8mCi 125I粒子。分别于粒子植入前2d（基础状态，T1）、植入后2、7、14、30、60d（T2-6）时取6只大鼠，测定机械缩足反射阈值（MWT）和热缩足潜伏期（TWL）。3组分别于粒子植入后14、60d时取6只大鼠，取kDRG，光镜下观察病理学结果。结果与A组比较，B组T4,5时MWT降低，L时阿L缩短，C组T3,4时MWT降低，T6时MWT升高,TWL延长（P〈0．05）。与B组比较，C组R时MWT升高，TWL延长（P（0．05）。A组T4,6时DRG神经元胞体形态和结构未见异常。B组和C组T4,6时DRG神经元损伤明显，且随着植入后时间延长，损伤更明显，C组DRG神经元损伤更明显。结论椎间孔植入高活度125I粒子可达到DRG放射切除术的效果。

Objective To evaluate the histologic changes of dorsal root ganglion （DRG） and pain thresh- old following implantation of iodine-125 （125 I） seeds in the lumbar intervertebral foramina in rats. Methods Thirty- six adult male SD rats aged 6 months weighing 220-250 g were randomly assigned into 3 groups（ n = 12 each）： group sham operation （group A） and groups low and high radioactive 125I seeds （groups B and C）. 125I seeds of 0.4 and 0.8 mCi were implanted in L4.5 and L5,6 intervertebral foramina in groups B and C respectively. Paw with- drawal threshold to von Frey filament stimulation （MWT） and paw withdrawal latency to thermal nociceptive stimuli （TWL） were measured 2 days before （T1 ,baseline） and at 2, 7, 14, 30 and 60 days after implantation （T2.6） in 6 animals in each group. The remaining 6 animals in each group were sacrificed at 14 and 60 days after 125I seeds implantation for microscopic examination of Ls DRG. Results MWT and TWL were significantly decreased after 1251 seeds implantation at T4 compared with the baseline values at T1 in both groups, and returned to the baseline in group B and were significantly increased in group C at T6 . The neurons were severely injured in DRG in groups B and C in a time-and dose-dependent manner. Conclusion Implantation of 125I seeds in intervertebral foramen can induce radiation resection of DRG.