NEUROPROTECTIVE EFFECT OF 17 β-ESTRADIOL ON LEARNING AND MEMORY PROCESSES AFFECTED BY NEONATAL X-RADIATION

CACERES, L.G.; ZORRILLA ZUBILETE M.A.; URAN, S.L.; SARACENO, E.; CAPANI, F.; GUELMAN, L.R.

Huerta Grande, Córdoba, Argentina

Congreso; I Reunión Conjunta de Neurociencias (IRCN); 2009

IRCN

Developing Central Nervous System (CNS) is vulnerable to radiationinducedreactive oxygen species (ROS). The consequent oxidative stresshas been shown to produce behavioral, biochemical and morphologicalchanges. The aim of the present work was to test if 17 β-estradiol (βE)a potential neuroprotector, was able to counteract radiation-inducedchanges in the hippocampus (Hip). Since a relationship between dendriticspines and memory processes has been postulated, the density of dendriticspines was assessed in irradiated Hip as well as an hippocampal-relatedmemory test. Neonatal male Wistar rats were X-irradiated (5 Gy) in theircephalic end and a group of these animals (E2) was treated with βE (5μg/g). Inhibitory avoidance (IA) and ROS levels, as well as the levels of PKC-a protein involved in the memory mechanism- were evaluated in the Hip.A morphological assessment of dendritic spines was also performed at 30postnatal days. The increase in the number of dendritic spines in CA1 regionof the irradiated group was partially restored with the administration of βE.However, it was not able to modify the improvement in the performancein the IA test observed in irradiated animals. The PKC activity in the E2group remained increased after the treatment, although a decrease inPKC translocation to the membrane was observed, indicating an attemptto restore control PKC activity. Finally, the increase in basal ROS levelsinduced by X-rays was restored. These results suggest that βE was able tocounteract, at least in part, the effects of X-rays on the Hip at behavioral,biochemical and morphological levels. Since ROS have been involved inPKC dynamics, an antioxidant mechanism for βE could be postulated