碩士 / 國立成功大學 / 生理學研究所 / 92 / Tinnitus is a phantom sensation of sound in the absence of external stimulations and its pathogenesis is unclear. Overdose of salicylate (SA) is known to cause tinnitus in both human and animals. Local application of SA in the bulla suppresses evoked potential to sound suggesting a peripheral action of SA at the cochlea. Systemic application of SA also induces over-activities of central auditory neurons suggesting a central action. In this study, the effects of SA applied at two different routes were compared in order to elucidate the action sites. Fos-immunohistochemistry was used to reveal the hyper-activity in the brainstem nuclei. Adult rats were divided into two groups for aseptic surgery. The first group was intraperitoneally implanted with osmotic pumps that would sustain release SA for 7 days. The second group had a SA-presoaked gelfoam placed over the round window in the bullae for 6 days. Controls received similar procedures with vehicle-treatments. Brains were processed for Fos-immunohistochemistry on thick frozen sections according to the conventional ABC method. For comparison, a limited number of animals also received a 5-daily SA injection. For some animals, SA levels in the perilymph and cerebrospinal fluid were measured at different time points with mass spectrometry (ESI-MS/MS).
Both the osmotic pump and gelfoam applications that released SA slowly were effective in raising Fos-activity labeling both in the inferior colliculus and lateral superior olivary complex in a manner rather similar to the multiple-daily injection protocol, suggesting a possible occurrence of tinnitus. Following intra-bullar applications there was a rapid increase of SA in perilymph followed by a delayed increase in CSF to about the level, suggesting an effective fluid passage linking the two compartments likely through the cochlear aqueduct. Intra-peritoneal applications also led to a rapid rise in SA level in the perilymph at a level higher than the CSF, suggesting the presence of an active secretion mechanism in the cochlea. The fact that SA when applied locally to the cochlea, even on one side, was effective suggested that a peripheral site was likely involved but may also require the action at the central nervous system. The relatively high level of Fos-expression at the IC of control rats was discussed with respect to a physiological tinnitus, which might subside in Fos-expression after animals were adapted to a silent environment.
| Identifer | oai:union.ndltd.org:TW/092NCKU5116005 |
| Date | January 2004 |
| Creators | Yu-Ching Chu, 朱育靜 |
| Contributors | Paul Wai-Fung Poon, 潘偉豐 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 44 |
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