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

CACERES, L.G; URAN, S.L; SARACENO, E; CAPANI, F; GUELMAN, L

Huerta Grande, Córdoba, Argentina

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

SAN y Taller de Neurociencias

Developing Central Nervous System (CNS) is vulnerable to radiation-induced reactive oxygen species (ROS). The consequent oxidative stress has been shown to produce changes at behavioral, biochemical and morphological levels in the brain. The aim of the present work was to test if 17 ß-estradiol, a potential neuroprotector, was able to counteract these changes in the hippocampus, a CNS region mainly involved in mechanisms of learning and memory. Neonatal male Wistar rats were X-irradiated (5 Gy) in their cephalic ends up to 48hs of postnatal life and a group of this animals (E2) was treated with 17 ß-estradiol (5 ìg/g). Inhibitory avoidance (IA) test and ROS levels, as well as the levels of PKC -a protein involved in the memory mechanism- were determined in the hippocampus. Morphological assessments, through inmunofluorescence using faloidine conjugate with alexa 568, were also performed at 30 postnatal days. The increase in the number of dendritic spines in the irradiated group (positive actin neurons), in CA1 region, was partially restore with the administration of 17 ß-estradiol, but its action was not able to decrease the performance improvement in the IA test to control levels. The PKC activity in the E2 group continued to increase after the treatment, however, the 17 ß-estradiol decrese the PKC traslocation to the membrane and the increase in basal ROS levels in the irradiated group were also restored. These results suggest that 17 ß-estradiol was able to counteract in part the effects of X-rays on the hippocampus at behavioral, biochemical and morphological levels, probably acting on molecular targets and through an antioxidant mechanism.