Gisone Pablo, Boveris Alejandro D, Dubner Diana, Perez María Rosario, Robello Elizabeth, Puntarulo Susana
Laboratorio de Radiopatología, Autoridad Regulatoria Nuclear, Buenos Aires, Argentina.
Neurotoxicology. 2003 Mar;24(2):245-53. doi: 10.1016/S0161-813X(02)00166-3.
Pregnant Wistar rats were exposed on day 17 of gestation to 1 Gy gamma irradiation from a Co(60) source. Even though it is established that gamma radiation-dependent damage is mainly due to free radical generation neither the ascorbyl radical/ascorbate ratio nor the lipid radical content in developing rat brain were affected by prenatal irradiation. A distinctive EPR signal for the adduct NO-Fe-MGD (g=2.03 and a(N)=12.5 G) was detected in brain homogenates prepared from irradiated rats. Nitric oxide (NO)-dependent EPR signal increased in a time-dependent manner up to 2h post-irradiation. NO concentration in unirradiated brains was 37+/-4 pmol/g brain and 45+/-2, 77+/-5 and 216+/-6 after 30, 60 and 120 min post-irradiation, respectively. Total nitric oxide synthase activity was increased by 77 and 51% after 30 and 60 min post-irradiation, respectively, and returned to control values after 120 min. Thus, increased NO steady-state concentration could be ascribed to an increase in NOS activity. Taken as a whole, these results suggest that NO might act to protect the developing brain from the cytotoxicity of reactive species.
妊娠第17天的Wistar大鼠暴露于来自钴（60）源的1 Gyγ射线照射下。尽管已经确定γ射线依赖性损伤主要是由于自由基的产生，但发育中大鼠大脑中的抗坏血酸自由基/抗坏血酸比率和脂质自由基含量均未受到产前照射的影响。在从受照射大鼠制备的脑匀浆中检测到加合物NO-Fe-MGD的独特电子顺磁共振信号（g = 2.03，a（N）= 12.5 G）。依赖于一氧化氮（NO）的电子顺磁共振信号在照射后2小时内呈时间依赖性增加。未照射大脑中的NO浓度为37±4 pmol/g脑，照射后30、60和120分钟分别为45±2、77±5和216±6。照射后30和60分钟，总一氧化氮合酶活性分别增加了77%和51%，120分钟后恢复到对照值。因此，NO稳态浓度的增加可能归因于一氧化氮合酶活性的增加。总体而言，这些结果表明NO可能起到保护发育中的大脑免受活性物质细胞毒性的作用。
