TWO NOISE-EXPOSURESCHEDULES DIFFERENTIALLY AFFECT RAT BEHAVIORAL PARAMETERS AND CAN BE ALTERED BY ENRICHED ENVIRONMENT REARING

MOLINA, SJ; CAPANI, F; GUELMAN, LR

Río de janeiro

Congreso; 9th World Congress of the International Brain research Organization (IBRO); 2015

International Brain research Organization (IBRO)

It is know n that noise exposure can induce transient or permanent hearing loss. How ever, few data are available regarding its effects on extra-auditory structures, mainly w ithin developing Central Nervous System. Previous studies of our laboratory show ed that exposure of immature rats (15-days-old) to moderate noise during 2 hours, in different exposure schedules, can induce hippocampus-related behavioral, biochemical and histological alterations. Moreover, rearing these animals in an enriched environment (EE) has show n to be an effective protective tool w hich almost fully prevented noise-induced behavioral changes.Nevertheless, no data on the behavioral effects induced by noise exposure at earlier ages have been obtained yet. Therefore, the aim of the present w ork w as to test the behavioral effects induced in 7-days-old rats after moderate noise exposure using different schedules, and if EEcan prevent them. Rats of 7 days w ere exposed during 2 hours to w hite noise (95-97 dBA), for one day (acute exposure) or five consecutive days (chronic exposure), using an ?ad-hoc? sound camera. After w eaning, groups of 3-4 rats w ere transferred to an enriched cage, consisting of toys, a w heel, tunnels and ramps, w hile other groups w ere placed in standard cages. One w eek later, different behavioral tests w ere performed. Results show that rats exposed to chronic noise had a better performance in associative memory task w hen compared w ith control animals, w hereas no significant changes w ere found in rats exposed to acute noise. Interestingly, all the exposed rats that w ere reared in an EEshow ed a better performance on this task. On the other hand, no changes in habituation memory w ere observed in rats exposed to noise in either noise schedule. How ever, significant differences w ere found in exposed rats reared in an EE. Finally, chronic noise-exposed rats show ed no changes in anxiety-like behaviors, w hereas rearing in an EEinduced a decrease in these behavior. Otherw ise, rats exposed to acute noise show ed an increase in anxiety-like behaviors, and rearing in an EEthe difference w as even more pronounced. These findings suggest that different noise exposure schedules (either acute or chronic) at an early developmental age might differentially affect behavioral performances. In addition, rearing in an EEimproved the performance in associative memory in both schedules w hen compared w ith standard cages. Conversely, opposite results w ere observed betw een both schedules in anxiety-like behavior. Moreover, although no changes w ere observed in habituation memory after either schedule of noise exposure, opposing changes betw een both schedules w ere found w hen exposed rats w ere reared in an EE. Therefore, it could be concluded that visual, social and physical stimulation during the peri-adolescence period could interact w ith the effects induced by an earlier exposure to a physical agent such as noise, generating different emotional and behavioral parameters.