Repetitives Läm -Modell

A new animal model was developed, in which drugs can be tested for their efficacy to influence inner ear function. In the model, guinea pigs were exposed twice for a period of 24 h to a 100-dB(A) broadband noise. After exposure to this repetitive low-level noise they had a temporary threshold shift of about 40-50 dB HL. After each noise application the hearing recovered spontaneously to a normal threshold, but after the second noise exposure the recovery was significantly slower. This retarded recovery was measured by auditory brain stem response without and with administration of drugs like pentoxifylline, dextran, steroids and a combination of drugs. The recovery in the second period showed no significant difference after application of pentoxifylline and dextran, whereas in the groups treated with cottisone or a combination of all three drugs the recovery was significantly faster than in the control group. The repetitive low-level noise model is more 'physiologic' in comparison with the damages obtained by hypoxia, ototoxic drugs and freezing. The retarded recovery after the second period of noise exposure gives the opportunity to investigate the effectiveness of drugs in the treatment of disorders of inner ear function.