The dose-effect relationship after the exposure of trigeminal nerve to gamma knife irradiation

Objective: To elucidate the potential damage of different doses of gamma knife irradiation to the trigeminal nerve tissues in rats, and to provide theoretical basis for the optimal strategy to treat trigeminal neuralgia pain with gamma knife. Methods: Totally 65 adult male SD rats were irradiated with different doses of 20, 40, 80 and 160 Gy targeting to the trigeminal nerve, and the behaviors of the rats were observed at 1, 2 and 4 weeks post-irradiation. To observe the conditions of cell morphological changes, autophagy, DNA damage and repair, the brain tissues were sectioned after fixing and embedding, followed by staining with HE, Nissl dyes, and immunohistochemical staining was used for MAPLC3B, 53BP1 and XRCC1 molecules. Results: All the rats survived. There was neither behavioral nor cytology abnormality in 20 and 40 Gy groups. In both 80 and 160 Gy groups at 4 weeks post-irradiation, hair loss took place in the irradiated part and the surrounding area, forming the alopecic spots on the rats' head. HE, Nissl, LC3B, 53BP1 and XRCC1 staining showed that neuron cell shrinkage, expansion and other obvious changes occurred in 80 and 160 Gy groups, and the incidence of autophagy and DNA damage were detectable, especially at 160 Gy. DNA repair in neuron cells was obvious at 40 Gy. Conclusions: Gamma knife irradiation to the trigeminal nerve showed a significant dose-effect relationship. (authors)