Streptomycin ototoxicity and hair cell regeneration in the adult pigeon utricle

Objective: The purpose of this study was to develop a technique to investig ate the regeneration of utricular hair cells in the adult pigeon (Columba l ivia) following complete hair cell loss through administration of streptomy cin. Study Design: Experimental animal study. Methods: Animals were divided into four groups. Group 1 received 10 to 15 days of systemic streptomycin injections, Animals in Groups 2 and 3 received a single direct placement of a 1-, 2-, 4-, or 8-mg streptomycin dose into the perilymphatic space, Anim als in Groups 1 and 2 were analyzed within 1 week from injection to investi gate hair cell destruction, whereas Group 3 was investigated at later dates to study hair cell recovery. Group 4 animals received a control injection of saline into the perilymphatic space. Damage and recovery were quantified by counting hair cells in isolated utricles using scanning electron micros copy. Results: Although systemic injections failed to reliably achieve comp lete utricular hair cell destruction, a single direct placement of a 2-, 4- , or 8-mg streptomycin dose caused complete destruction within the first we ek. Incomplete hair cell loss was observed with the 1-mg dose. Over the lon g term, regeneration of the hair cells was seen with the 2-mg dose but not the 8-mg dose. Control injections of saline into the perilymphatic space ca used no measurable hair cell loss. Conclusions: Direct placement of strepto mycin into the perilymph is an effective, reliable method for complete dest ruction of utricular hair cells while preserving the regenerative potential of the neuroepithelium.