RAT HIPPOCAMPAL ALTERATIONS COULD UNDERLIE BEHAVIORAL ABNORMALITIES INDUCED BY MODERATE NOISE EXPOSURE

URAN SL; AON BERTOLINO, ML; CACERES LG; CAPANI F; GUELMAN LR

New Orleans

Congreso; 42th Annual Meeting of the Society for Neuroscience (SFN); 2012

Society for Neuroscience (SFN)

Noise exposure is known to affect auditory structures on living organisms. However, it should not be overlooked that many of the effects of noise would be extra-auditory. Previous behavioral data of our laboratory demonstrated that noise was able to induce a number of behavioral alterations in exposed rats, mainly related to the hippocampus (Hip). Therefore, the aim of the present work was to reveal novel data about the susceptibility of developing rat Hip to moderate noise levels through the assessment of hippocampal-related behavioral tasks. Male Wistar rats were exposed to moderate levels of white noise (95-97 dB SPL, 2 hours daily) for one day (acute noise exposure, ANE) or between postnatal days 15 and 30 (sub-acute noise exposure, SANE). PND 15 animals were randomly assigned to each experimental group. Short (ST) and long term (LT) habituation and recognition memory (OR) assessments were performed at PND 30 and at 15 days from the end of noise exposure (PND 45). ST results showed that groups of PND 30 and PND 45 rats significantly decreased the number of lines crossed in the second session of the OF task, although a more significant reduction was observed in control (Ct) group when compared with noise-exposed animals. When PND 30 animals were tested  in the OR task, Ct and ANE rats showed an increased exploration time of the novel (N) when compared with the familiar (F) object, whereas exploration time of both objects was similar in PND 30 SANE rats.  In contrast, PND 45 results showed that rats explored more the N object than the F, both in Ct and in noise-exposed rats. LT results showed that whereas Ct PND 30 rats decreased the number of lines crossed in the second session of the OF task, noise-exposed animals crossed the same number of lines in both sessions. Moreover, data obtained from SANE rats evaluated at PND 45 showed similar results than those observed in SANE PND 30 animals. Likewise, in OR, whereas PND 30 Ct animals explored more the N than the F object, exploration time on both objects was similar in noise-exposed animals. Similarly, while PND 45 Ct rats explored more time the N than the F object, noise-exposed rats explored both objects equal time. Results showed that moderate levels of white noise either through ANE or SANE schemes, can induce impairments in habituation and recognition memory, observed mainly at LT, that seemed to be long-lasting. It would be suggested that whereas ST processes remained unaffected after noise exposure, a significant impairment was observed after LT testing in both noise schemes, supporting the hypothesis that ST and LT processing mechanisms could involve different mechanisms of memory.