Gamma Irradiation Effect on Cellular Iron in Neuronal Precursors Cells

GALATRO A; ROBELLO E; DUBNER D; PUNTARULO S

Santa Fé

Congreso; XXXV Annual Meeting of the Argentinean Biophysical Society; 2006

This study was aimed to address the effect of  irradiation on both the iron and ferritin content in the developing rat brain exposed in utero with 1 Gy of gamma irradiation. Female Wistar rats were mated overnight and the following morning sperm-positive vaginal smear was checked to assess day 0 of pregnancy. The pregnant rats were irradiated with 1 Gy of gamma radiation at 17th day of their gestational period, and the fetal brains were removed under general anesthesia at 2 or 4 h post-irradiation (pi).Total Fe content of the developing brain was determined by measuring the formation of Fe2+-batophenanthroline complex [1]. Total Fe content in non-irradiated fetal brains, and irradiated fetal brains at 2 and 4 h pi were 7110, 6150 and 12220 pmol/mg tissue, respectively. Labile iron pool (LIP) from maternal plasma and fetal brain tissue was determined by a fluorescence technique with the Fe sensor calcein [2]. LIP content in non-irradiated maternal plasma, and irradiated ones at 2 and 4 h pi were 1.90.4, 41 and 51 M, respectively. LIP in non-irradiated developing brain, and irradiated brains at 2 and 4 h pi were 3.80.7, 1.00.2 and 3±1 pmol/mg tissue, respectively. The ferritin (Ft) content from total extract protein of fetal rat brain cortex was analyzed using a Western blotting assay. Subunits analyses of the protein by SDS-polyacrilamide gel electrophoresis indicated that the protein was composed by a 20 kDa protein subunit, confirmed by immunoblotting. Using a semiquantitative assay, an increase in the ferritin content was detected in fetal rat brain at 1 and 2 h pi. These results suggest that the increase in the total Fe content at 4 h pi is probably due to a Fe uptake from maternal blood. However, there was no significant increase in the LIP in the irradiated developing brain up to 4 h pi. This fact is probably due to a regulation of LIP levels by ferritin uptake of the available Fe in order to buffer this potentially dangerous free radical generation catalyst.