CEFYBO   02669
CENTRO DE ESTUDIOS FARMACOLOGICOS Y BOTANICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
IMPACT OF LOUD NOISE ON RAT SPATIAL AND ASSOCIATIVE MEMORY. HIPPOCAMPAL NEURONAL ALTERATION AND OXIDATIVE STATUS IMBALANCE
Autor/es:
URAN, SL; AÓN, L; CACERES, LG; CAPANI, F; GUELMAN, LR
Lugar:
Chicago, Ill, USA
Reunión:
Congreso; 39th Annual Meeting of the Society for Neuroscience (SFN); 2009
Institución organizadora:
Society for Neuroscience (SFN)
Resumen:
Acoustic contamination is produced in the environment by the presence of noise which can affect cardiovascular, gastrointestinal and hormonal systems through oxidative stress generation. However, noise impact on Central Nervous System has not been extensively investigated. A noisy environment can cause not only physiological changes, but also can affect memory processes. Since hippocampus has been involved both in spatial and associative memories, the aim of the present work was to test if the exposure to loud noise can affect hippocampal-related memories. In addition, hippocampal histology and oxidative status were tested in exposed rats. Male Wistar rats of 15 days were exposed to white noise (100dB, 2h/day) and separated into two groups, acute (AE, 2h/day) and chronic exposure (CE, 2h/day for 15 d). 30-days-old rats were evaluated in a radial arm maze (RAM) to test spatial memory and the passive avoidance test (PA) was used to evaluate the associative memory. The levels of ROS and the activities of superoxide dismutase (SOD) and catalase (CAT) were measured in 30-days-old rats. Moreover, histological assessment was also performed. Results showed that noise exposed 30-days-old rats made significatively more errors in the RAM at the first block of sessions (mean of 2 sessions) than control animals (C, 3.6 ± 0.33; AE, 7.4 ± 0.91, p< 0.05; CE, 7.2 ± 1.36,  p< 0.05). In addition, latency to complete the maze increased significatively in CE at the first block (C, 2.05 ± 0.02; AE, 2.09 ± 0.24, NS; CE, 3.36 ± 1.04,  p< 0.05). Animals exposed to CE showed an impairment in PA test, with a decreased latency to enter the dark compartment when compared to control animals, 24 hs after the electric footshock (rate T2/T1: C, 34.4 ± 7.63; AE, 33.1 ± 14.1, NS; CE, 2.7 ± 1, p< 0.05). The basal ROS levels were decreased in exposed animals (pmol/mg tissue/min: C, 0.52 ± 0.04; AE,  0.14 ± 0.009, p< 0.001; CE, 0.19 ± 0.018, p< 0.001), while antioxidant enzymes activities were increased after noise exposure (UCAT mg tissue: C, 0.0099 ± 0.002; AE, 0.026 ± 0.002, p< 0.001; CE, 0.017 ± 0.001, p< 0.05; USOD/mg tissue: C, 0.29 ± 0.03; AE, 0.42 ± 0.03, p< 0.05; CE, 0.34 ± 0.02, NS). Histological changes were found in noise exposed rats, with neuronal death, nuclear hyperchromasia  and  citoplasmatic shrinkage, both in CA1 and dentate gyrus regions. These results suggest that AE and CE to loud noise are capable of inducing spatial and associative memory impairments in developing rats, mainly related to hippocampal histological damage. The increase in hippocampal CAT and SOD activities could be triggered as a compensatory response to noise-induced damage, leading to a decrease in basal ROS levels.