Does Aluminum Cause Ototoxicity in Rats

Background: Aluminum (Al) is a nonessential and toxic metal to which humans are frequently exposed. Except one study which revealed adverse effects of serum Al levels on the auditory functions in hemodialysis patients, there is not any other study on the effects of Al on auditory functions. Study design: Acute and chronic effects of Al on rat auditory system were investigated in that randomized controlled study. Methods: Forty five male Sprague-Dawley rats were included. Rats were divided into six groups according to the dose and route of Aluminum chloride (AlCl 3): in groups A (n=7), B (n=9), and C (n=9), intraperitoneally (IP) AlCl 3 was injected in doses of 1mg/kg, 5mg/kg, and 80mg/kg, respectively; in control group (group K, n=6), saline was injected IP; in groups D (n=7) and E (n=7) oral AlCl 3 was administered in doses of 5mg/kg, and 50mg/kg, respectively. OAE measurement was performed for four times in IP AlCl 3 groups; before and on the 1 st , 7 th , and 14 th days after aluminum administration. In oral group OAE measurement was performed before and on the 1 st , 2 nd , and 3 rd months after aluminum administration. The distortion product otoacoustic emissions (DPOAEs) at 2f1-f2 were recorded and analyzed. Histological examination of the cochlea was performed. Results: DPOAE measurements of all groups before and after AlCl 3 administrations were not statistically different. Histological examination revealed normal stria vascularis, spiral ganglion and organ of corti in all groups. Conclusion: Neither acute nor chronic administration of AlCl 3 in aforementioned doses and routes caused neither clinical nor histological ototoxicity.