Aminoglycoside ototoxicity and antioxidant protection

ABSTRACT

Sensory hair cells are mechanotransducers of the inner ear that are essential for hearing. The normal function and integrity of hair cells may be altered by endogenous factors such as liberation of free radicals during normal cellular functions or environmental factors as ototoxic drugs. Aminoglycosides are commonly used antibiotics combination with high efficacy and low cost, they are the antibiotics of choice in developing countries. Although highly efficacious, their use is limited due to their severe toxicity to the inner ear. It is well established that reactive oxygen species are generated in hair cells exposed to aminoglycoside. So, enhancing antioxidant levels promotes hair cell survival while preserving function. Thirty healthy adult guinea pigs used in this study were divided into three groups, control, and tow experimental groups. Group [A] animals received antioxidant treatment one week prior to and concomitant with one week of gentamicine treatment. Group [B] animals received gentamicine by intramuscular injection for one week and control group received oral and intramuscular saline instead of drugs. A joined formula of dietary antioxidants was used. Mitochondrial activity was used as an index for cellular vitality and activity in organ of Corti cells. There was a highly significant [p<0.0001] mitochondrial activity in organ of Corti cells with group A animals. On the other hand mitochondria1 activity was significantly lower in organ of Corti cells of group B animals [p> 0.05] compared to group A and control group. In conclusion the results of this study suggest that, the introduction of free radical scavengers might help to ameliorate and protect against aminoglycoside ototoxicity, as free radicals play an important role in gentamicine ototoxicity