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Evaluation of long-term effects of early auditory deprivation: an animal model for otitis media Adam, Trudy


This project aimed to establish a developmental animal model for the long-term effects of Otitis Media experienced in youth. The procedure employed was based on a model that mimmics the acute physiological symptomology of the syndrome. It consisted of the infusion of lipopolysaccharides (derived from the plasmolemmae of Klebsiella pneumoniae, a pathogen known to cause the infection in nature) into the middle ear cavity. In the young (12 day old) animal, it was found that a dosage 200 times that employed in previous models was necessary to induce like symptomology. This is thought to be due to the boosted immunity of the present rat pups stemming from clostrum in the mother’s initial milk production. Rat pups were raised to an age of approximately 35 days with their respective effusion conditions. Groups of rats were used to study the effects of monolateral versus bilateral infections, severe versus mild hearing reductions, and in steady-state versus fluctuating conditions. During and after the experience of middle ear effusion produced by lipopolysaccharide injection, audiograms were constructed to examine reductions in hearing level associated with the presence of the mucoid mass. Upon adulthood, prior to any other testing, open-field behavior was examined; focussing on exploration and re-exploration tendancies, reaction to novelty, and habituation to new environments. No consistent differences were noted for emotionality, reaction to novelty, or exploratory behavior in general. Subsequently, the spatial navigational abilities of rats being studied were examined. Testing was conducted in both the visual (non-deprived) and auditory (deprived) modalities, employing the standard spatial water maze task. As expected, no group differences were observed in the visual version of the task. However, the auditory task also failed to detect group differences. Implications and directions for future study of Otitis Media are discussed, and alternative behavioral paradigms suggested.

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