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Medicina, Argentina

Uran S.L.,1a Catedra de Farmacologia | Caceres L.G.,1a Catedra de Farmacologia | Guelman L.R.,1a Catedra de Farmacologia
Brain Research | Year: 2010

Living organisms are exposed to potentially hazardous noise levels coming from the environment. Besides the direct effect on hearing, extra-auditory noise-associated effects should be considered. Since loud noise has been suggested to induce central nervous system symptoms, the aim of the present work was to investigate the effect of acute (ANE) and chronic noise exposures (CNE) on different behavioral tasks. To understand the mechanisms involved, levels of oxidative status markers were determined in two areas related to memory processes, the hippocampus (Hip) and the cerebellum (CE). 15-day-old male Wistar rats were exposed to loud noise (95-97 dB, 2 h/day), at ANE or CNE. At 30 days, rats were subjected to different CE and Hip-related behavioral tasks. Reactive oxygen species (ROS) levels and antioxidant enzyme activities (CAT and SOD) were also assessed. Results show impairments in spatial and associative memory in noise-exposed animals. Moreover, a decrease in anxiety levels and an increase in habituation memory were observed in CNE animals. While an increase in cerebellar ROS levels was found early after the first noise exposure, a decrease was found in the CE and the Hip at 30 days. The activity of hippocampal CAT was increased early and remained high in ANE rats, while it was unchanged in the CE. Finally, although SOD activity was decreased immediately after the first noise exposure, its levels were increased at 30 days in ANE rats. In summary, the present study shows that an imbalance in oxidative status induced by noise exposure could underlie behavioral changes, some of which would be long-lasting. © 2010 Elsevier B.V. All rights reserved.

Caceres L.G.,1a Catedra de Farmacologia | Aon Bertolino L.,CONICET | Saraceno G.E.,CONICET | Zorrilla Zubilete M.A.,1a Catedra de Farmacologia | And 3 more authors.
Brain Research | Year: 2010

Ionizing radiations induce oxidative stress on target tissues, mainly through the generation of reactive oxygen species (ROS). However, there are few data available on the behavioral effects of moderate doses of ionizing radiation. The aim of the present work was to evaluate the performance of adult rats irradiated at birth in different hippocampal-dependent behavioral tasks and to establish a relationship with the oxidative status and histological changes in rat hippocampus (Hip). Male Wistar rats were irradiated with 5 Gy of X rays between 24 and 48 h after birth. Thirty days later, rats were subjected to open field, object recognition and inhibitory avoidance tasks. In addition, oxidative status markers as well as protein kinase C (PKC) activity and histological changes were assessed in control and irradiated Hip. Results show an impairment in recognition and habituation memories in 30-day-old animals exposed to neonatal ionizing radiation, both at short- (ST) and at long-term (LT), whereas an improvement in associative memory was observed at ST. In addition, histological alterations were observed in irradiated Hip. Although an increase in ROS levels and PKC activity were found in irradiated Hip, no changes in the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were observed. Taken together, our results support the hypothesis that an increased PKC activity, induced by neonatal ionizing radiation on rat Hip, could play a role in the generation of an imbalance between ROS levels and antioxidant systems and might underlie radiation-induced hippocampal histological damage as well as the Hip-dependent behavioral changes found in irradiated rats. © 2009 Elsevier B.V. All rights reserved.

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