CHANGES OF HIPPOCAMPAL OXIDATIVE STATUS IN IMMATURE RATS EXPOSED TO NOISE: INFLUENCE OF ELAPSED TIME AFTER EXPOSURE AND ENVIRONMENTAL STIMULATION

MOLINA, SJ; CAPANI, F; GUELMAN, LR

Washington DC

Congreso; 47th Annual Meeting of the Society for Neuroscience (SFN); 2017

Society for Neuroscience

Previous studies of our laboratory showed that exposure of immature rats to moderate noise can induce hippocampus (HC)-related behavioral, biochemical and histological alterations during the peri-adolescence period. In addition, rearing animals in an enriched environment (EE) has shown to be effective in the reversal of most behavioral alterations. However, comparative data of HC oxidative levels at different post-exposure ages were not obtained yet. Thus, the aim of the present work was to test the potential differences in HC oxidative status of rats exposed to noise at an early developmental age as well as the possible reversal of these changes by rearing in an EE for different periods.Male Wistar rats of 7 days were exposed for 2 hours to white noise (95-97 dB). After weaning, groups of 3-4 rats were transferred to an enriched cage, consisting of different toys, a wheel, plastic tunnels and ramps. Other groups were placed in standard cages. One or two weeks later, levels of Trx1 -an antioxidant of the thioredoxin family- were tested through Western blot experiments. Results showed that Trx-1 levels were increased in exposed animals one week after weaning, when compared with non-exposed rats. However, rearing animals in an EE was effective in restoring these differences. In contrast, when Trx-1 levels were tested two weeks after weaning, there were no significant differences in Trx-1 levels, neither in standard nor in enriched conditions.These findings suggest that an oxidative imbalance might be triggered after noise exposure that can be observed at least until three weeks after exposure. Nevertheless, as development continues, this parameter seemed to return to control values, suggesting that increasing age might compensate for antioxidant system dysfunction. On the other hand, whereas visual, social and physical stimulation during development seemed to be an effective strategy to reverse noise-induced changes three weeks after exposure, it resulted unsuccessful in more mature animals, even if EE was extended for two weeks. Therefore, it could be hypothesized that this intervention should operate only when an injurious agent is present. Together, these findings suggest that a narrow window of opportunity might exist, in which an environmental intervention such as EE might be effective.