125I粒子植入组织间照射对大鼠背根神经节影响的组织形态学研究

目的 探讨125I粒子源照射对SD大鼠背根神经节组织形态学的影响.方法 把体重150～180g的12只成年雄性SD大鼠用随机表法等分成6组；在l～6组大鼠的第5腰背根神经节周围分别植入O(钛质空壳作为健康对照组)、14.8、18.5、22.2、25.9和29.6 MBq的125I粒子源,观察大鼠的行为改变,在植入后不同时期,将大鼠分批处死,用Olympus BX51生物光学显微镜观察植入不同活度粒子,照射不同时间后,神经节及周围肌肉组织的形态学改变,并估算背根神经节受到的剂量.结果 125I粒子源植入后,大鼠的运动功能没有受到影响,7d后体重自然增长.光学显微镜结果显示,钛质空壳植入后引起个别神经节细胞轻度水肿,但核仁清晰,细胞质正常.18.5 MBq的125I粒子源植入30 d后,与植入14 d相比,细胞肿胀更明显,还出现了脱水核固缩、核碎裂现象.29.6 MBq的粒子源植入60d后大量细胞核消失、细胞核溶解、细胞质失水皱缩.同时,活度越大,粒子植入时间越长,神经节周围的肌肉组织纤维化越显著.结论 受到125I粒子源的照射后,背根神经节及周围组织的损伤程度与照射强度存在剂量依赖关系.植入125I粒子源可能对各种难治性疼痛产生一定的镇痛作用.

Histology study on the dorsal root ganglia of rats with 125I seed brachytherapy at intervertebral foramen

Objective To investigate the effect of the histological changes on rat dorsal root ganglia (DRG) after ¹²⁵I seed brachytherapy.Methods Twelve adult male Sprague-Dawley rats (150-180 g each) were randomly divided into 6 groups. ¹²⁵I seeds with different activities of 0 (Titanium shell), 14.8, 18.5, 22.2, 25.9 and 29.6 MBq were implanted to 6 groups of rats respectively and the behavioral changes of rats were observed. The rats were killed in different periods after implantation, the morphological changes in DRG and surrounding muscle tissue were observed with an Olympus BX51 optical microscope and then the irradiation doses were estimated.Results After ¹²⁵I seed implantation, the movement function of rats was not affected and the weight of rats gained after 7 days. After the titanium shell implantation, very few mild swelling was induced in neuroganglion cells that still had clear nucleolus and normal cytoplasm. At 14 days after 18.5 MBq seed implantation, cell swelling was more serious and cell dehydrating, nuclear condensation and nuclear fragmentation appeared after 30 days. At 60 days after 29.6 MBq of seed implantation, nuclear dissolution and cytoplasmic shrinkage were induced in a large number of cells. In general, the severity of fibrosis was aggravated with the time post-irradiation and the dose in the muscles around the ganglion.Conclusions After ¹²⁵I seed implantation, the injury degree of DRG tissue is dose-dependent, and the ¹²⁵I seed irradiation would have analgesic effect on releasing intractable pain.