NOISE-INDUCED MALADAPTIVE ANXIETY-LIKE AND RISK ASSESSMENT BEHAVIORS WERE REVERTED BY REARING PERIADOLESCENT RATS IN AN ENVIRONMENTAL ENRICHMENT.

MOLINA, SJ; MICELI, M; CAPANI, F; GUELMAN, LR

Chicago, IL

Congreso; . 45th Annual Meeting of the Society for Neuroscience (SFN); 2015

Society for Neuroscience (SFN)

It is known that noise exposure can induce hearing loss. However, few data are available regarding its effects on extra-auditory structures such as developing Central Nervous System. Previous studies of our laboratory showed that exposure of immature rats to moderate noise can induce anxiety-like behaviour alterations. Interestingly, rearing these animals in an enriched environment (EE) has shown to be an effective protective tool which can prevent some noise-induced behavioral changes. Risk assessment (RA) can be defined as the acts and postures serving as defensive behaviors against threatening dangers, which rodents use to cope with potentially unsafe situations, closely related to fear and anxiety behaviors. Nevertheless, no data on noise-induced RA effects have been obtained yet. Therefore, the aim of the present work was to test the effects of different schedules of noise exposure in 7-days-old rats on anxiety-like and RA behaviours as well as the potential preventive effect of EE rearing.Rats of 7 days were exposed during 2 hours to white noise (95-97 dBA), for one day (acute noise exposure, ANE) or five consecutive days (sub-acute noise exposure, SANE), using an ?ad-hoc? sound camera. After weaning, groups of 3-4 rats were transferred to an enriched cage, consisting of toys, a wheel, tunnels and ramps, while other groups were placed in standard cages. One week later, rats were subjected to elevated plus maze (EPM) and open field (OF) tasks.Results showed an increase in both anxiety-like and RA behaviors in ANE rats. In contrast, a decrease in most anxiety-like behaviors was found in SANE animals, whereas an increase in RA behaviors was observed. EE rearing was fully effective in reverting RA changes in both schedules. Interestingly, while a partial reversion was observed in anxiety-like behaviors in ANE rats, the decreased anxiety-like levels observed in SANE rats were normalized when animals were reared in EE. These findings suggest that rats exposed at an early developmental age to different noise exposure schedules might be differentially affected in emotion-related behavioral performances that EE rearing was able to reverse. It seems that the rearing of young rats in an EE tend to normalize anxiety-like behaviors, in particular in SANE animals. Conversely, the maladaptive RA behavior observed in noise-exposed animals was reestablished when animals were reared in an EE.Therefore, it could be concluded that visual, social and physical stimulation during the peri-adolescence period could interact with behavioral abnormalities induced by an earlier exposure to a physical agent such as noise, generating normalized emotional and behavioral parameters.