[Protective effect of allopurinol in the exposure to noise pulses]

Free oxygen radicals cause particularly severe tissues and organ damage. They appear to play an important role in the cochlea, mediating noise-exposure damage. In the present study 16 guinea pigs were implanted with permanent electrodes to record cochlear action potential. Eight animals were exposed to a 2-3 kHz, 125 dB SPL noise pulse, at a rate of 4 stimulations per second for 1.8 hours. Prior to noise exposure four out of eight animals were treated with a known dose of allopurinol. The remaining eight animals were used as controls. Endolymphatic malondialdehyde concentration was used as indicator of the lipid peroxidization processes exerted by the free radicals. No significant difference was found between the variations in hearing threshold and malondialdehyde concentration in the animals treated with allopurinol and then exposed to noise vs. the control group. The electophysiological and biochemical results have, therefore, demonstrated that preventative administration of allopurinol can provide valid protection vs. noise impulse damage.