Radiation-induced apoptosis of neural precursors cell cultures: early modulation of the response mediated by reactive oxygen and nitrogen species (ROS/RNS)

GISONE P; DUBNER D; ROBELLO E; MICHELIN S; PÉREZ MR

Madrid, España

Congreso; 11th International Congress of the International Radiation Protection Association (IRPA); 2004

Apoptosis, the typical mode of radiation-induced cell death in developing Central Nervous System (CNS), is closely related with the oxidative status. Enhanced radiation-induced generation of ROS/RNS has been observed after exposures to low radiation doses leading to cellular amplification of signal transduction and further molecular and cellular radiation-responses. Moreover Nitric oxide (NO) and hydroxil radical are implicated in domapinergic neurotoxicity in different paradigms. This study is an attempt to adress the participation of radiation-induced free radicals production, the contribution of endogenous NO generation, and the excitotoxic pathway, in the radiation-induced apoptosis of neural cortical precursors. Cortical cells  obtained from at 17 gestational day (gd) were irradiated with doses from 0,2 Gy to 2 Gy at a dose-rate of 0,3 Gy/m. A significant decrease of Luminol-dependent  Chemiluminescence  was evident 30 m after irradiation reaching basal levels at 120 m follow for a tendence to increasing values Incubations with Superoxide Dismutase (SOD) decreased significantly the chemiluminiscence in irradiated samples. NO content estimated by measuring the stable products NO2- and NO3- released to the culture medium in the same period, has shown a time-dependent accumulation from 1 h post-irradiation. The apoptosis, determined 24 h post-irradiation by flow citometry, morphology and DNA fragmentation, revealed a dose-effect relationship with  significant differences  from 0,4 Gy The samples pre-treated with 10 mM of N-acetyl cyteine (NAC) a precursor of intracellular GSH synthesis,  shown a significant decrease of the apoptosis. Apoptosis was significantly increased in irradiated cells after inhibition  of nitric oxide synthase (NOS) byL-NAME. We conclude that ROS/RNS play  a pivotal role in the early signaling pathway leading to a radiation-induced cell death.