Abstract:

Objective   To investigate the hypothesis that the central nervous system is involved in tinnitus by testing immediately early gene Arc/arg3.1 in the auditory brainstem. Methods  Forty-eight Wistar rats were randomly divided into 6 groups (n=8 in each group): During establishing a conditioned response, groupsⅠand Ⅳ received a single intraperitoneally injected (i.p.) dose of 400 mg sodium salicylate per kg bodyweight dissolved in physiological saline 2 hours before training, while groups Ⅱ and Ⅴ were injected i.p. with the same dose of physiological saline. Undisturbed controls were groups Ⅲ and Ⅵ. After group Ⅳ maneged to establish a model of tinnitus, these rats continued to receive injections of the same dose of sodium salicylate for ten days. Groups Ⅰ、 Ⅱ and Ⅲ were sacrificed and samples were harvested together; groups Ⅳ、 Ⅴ and Ⅵ were sacrificed and  were harvested together samples together. Then SYBR Green1 real-time relative quantitative RT-PCR was used to detect  expression of gene ARC/arg3.1 in these three auditory nuclei. Results   Expresseion levels of Arc mRNA in the cochlear nucleus first down-regulated （P＜0.05）then climbed back slightly（P＜0.05）; Arc mRNA of the inferior colliculus increased and maintained a high degree, but no longer climbed（P＜0.01）; finally, we failed to find any change in nuclei olivaris superior（P＞0.05）. Conclusions  The alteration of the Arc mRNA in the auditory brainstem further supports tinnitus-related plasticity in the auditory center.

Key words: Tinnitus; gene, Arc/arg3.1; auditory brainstem; Sodium salicylate