CONICET | Buscador de Institutos y Recursos Humanos

Acoustic contamination is produced in the environment by the presence of noise which can affect several systems through oxidative stress generation. Since hippocampus has been involved in associative memory, the aim of the present work was to test if the exposure to loud noise can affect hippocampal-related memory. 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). Passive avoidance test (PA) was used to evaluate the associative memory in 30-days-old rats. The levels of ROS and the activities of superoxide dismutase (SOD) and catalase (CAT) were measured at 30 days. Moreover, histological assessment was also performed. Results showed an impairment in PA test in exposed CE animals, with a decreased latency to enter the dark compartment, 24 hs after the electric footshock (rate T2/T1: AE, NS; CE, p<0.05). The basal ROS levels were decreased (AE, p<0.001; CE, p<0.001), while antioxidant enzymes activities were increased after noise exposure (CAT: AE, p<0.001; CE, p<0.05; SOD: AE, p<0.05; CE, NS). Histological changes were found, 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 associative memory impairments in developing rats, what is mainly related to hippocampal histological damage. The increase in CAT and SOD activities could be triggered as a compensatory response to noise-induced damage, leading to a decrease in basal ROS levels.