Differential changes in Fos-immunoreactivity at the auditory brainstem after chronic injections of salicylate in rats.
In human, salicylate-induced tinnitus sometimes occurs a few days after its administration, but the chronic effects of salicylate in animal models are not fully known. In this study, we revealed the distribution of active cells in the rat auditory brainstem by staining an activity marker Fos-protein after multiple daily injections of salicylate. Experimental animals were first given five daily doses of sodium salicylate (250 mg/kg, i.p.). On day 6 they were placed inside a sound room for 8 h before sacrifice. Immunohistochemistry showed a significant increase in the number of Fos-positive cells at the inferior colliculus (IC), particularly its central division. At the cochlear nucleus (CN), only a few Fos-stains were found at the dorsal nucleus while no Fos-stain appeared at the ventral nucleus. The scarcity of Fos-stains at the CN reflected more a lack of external sound inputs than an adaptation in Fos-expression. Since Fos-stains in CN could still be induced on day 6 following brief tonal stimulation. Results are consistent with the hypothesis that salicylate-induced tinnitus is a phantom sound perception related to overactivity of cells at the IC.
Wu
Jiunn Liang
JL
Department of Otolaryngology, National Cheng Kung University, Tainan, Taiwan.
Chiu
Tzai Wen
TW
Poon
Paul Wai Fung
PW
D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000818:Animals; D001306:Auditory Pathways / Q000378:metabolism*; D001933:Brain Stem / Q000378:metabolism*; D002452:Cell Count; D017626:Cochlear Nucleus / Q000166:cytology / Q000378:metabolism; D004334:Drug Administration Schedule; D007150:Immunohistochemistry; D007245:Inferior Colliculi / Q000166:cytology / Q000378:metabolism; D007267:Injections; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009622:Noise; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012459:Salicylates / Q000008:administration & dosage* / Q000097:blood; D013997:Time Factors
D016760:Proto-Oncogene Proteins c-fos; D012459:Salicylates