title: Implanting iodine-125 seeds into rat dorsal root ganglion for neuropathic pain: neuronal microdamage without impacting hind limb motion.
abstract: The use of iodine-125 ((125)I) in cancer treatment has been shown to relieve patients' pain. Considering dorsal root ganglia are critical for neural transmission between the peripheral and central nervous systems, we assumed that (125)I could be implanted into rat dorsal root ganglia to provide relief for neuropathic pain. (125)I seeds with different radioactivity (0, 14.8, 29.6 MBq) were implanted separately through L4-5 and L5-6 intervertebral foramen into the vicinity of the L5 dorsal root ganglion. von Frey hair results demonstrated the mechanical pain threshold was elevated after implanting (125)I seeds from the high radioactivity group. Transmission electron microscopy revealed that nuclear membrane shrinkage, nucleolar margination, widespread mitochondrial swelling, partial vacuolization, lysosome increase, and partial endoplasmic reticulum dilation were visible at 1,440 hours in the low radioactivity group and at 336 hours in the high radioactivity group. Abundant nuclear membrane shrinkage, partial fuzzy nuclear membrane and endoplasmic reticulum necrosis were observed at 1,440 hours in the high radioactivity group. No significant difference in combined behavioral scores was detected between preoperation and postoperation in the low and high radioactivity groups. These results suggested that the mechanical pain threshold was elevated after implanting (125)I seeds without influencing motor functions of the hind limb, although cell injury was present.
authors.affiliation: Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Tianjin, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Jiao
authors.affiliation: Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Tianjin, China.
authors.forename: Tengda
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Second Affiliated Hospital of Tianjin Medical University, Tianjin, China.
authors.forename: Huixing
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Tianjin, China.
authors.forename: Wenyi
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Tianjin, China.
authors.forename: Saijun
authors.initials: S
authors.lastname: Fan
authors.affiliation: Second Affiliated Hospital of Tianjin Medical University, Tianjin, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Huo
authors.affiliation: Second Affiliated Hospital of Tianjin Medical University, Tianjin, China.
authors.forename: Baosen
authors.initials: B
authors.lastname: Zheng
authors.affiliation: Second Affiliated Hospital of Tianjin Medical University, Tianjin, China.
authors.forename: Wenting
authors.initials: W
authors.lastname: Ma
keywords: analgesia; dorsal root ganglion injury; iodine-125; nerve regeneration; neural regeneration; neuropathic pain; pain threshold; radioactive seeds; ultrastructure