Neuronal sensitivity to carbon beams; Approach using growth cone collapse assay

Al-Jahdari, W. S.*; Suzuki, Yoshiyuki*; Yoshida, Yukari*; Hamada, Nobuyuki*; Noda, Shinei*; Shirai, Katsuyuki*; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko; Nakano, Takashi*

Dorsal root ganglia (DRG) and sympathetic ganglion chains (SYMP) were isolated from day-16 (mature) and day-8 (immature) chick embryos and cultured for 20 h. Thereafter, neurons were exposed to graded doses of X-rays, or high-LET C ions. Morphological, time- and dose-dependence changes of the neurons were examined quantitatively by GCC assay. Apoptosis induction was examined using TUNEL assay. Carbon-beams induced GCC and neurite destruction in a time and dose dependent manner. Day-8 neurons were more radiosensitive than day-16 neurons (p=0.01). At 12 h post-irradiation, 20 Gy carbon-beams and 30 Gy X-ray induced about 65% and 25% apoptosis, respectively. The carbon-beams were 3.3-4.6-fold more effective than X-rays for GCC and apoptosis induction in both day-16 and day-8 neurons.