Neurotrophic and antioxidant effects of silymarin comparable to 4-methylcatechol in protection against gentamicin-induced ototoxicity in guinea pigs

Background: despite that gentamicin is a very effective aminoglycoside,its potential ototoxicity which is of irreversible nature makes a challenge and limitation for its use. this study was designed to investigate possible neurotrophic and antioxidant effects of silymarin comparable to 4-methylcatechol in protection against gentamicin-induced ototoxicity. methods and results: twenty pigmented guinea pigs were divided into four equal groups,where group i served as normal control group. the other groups received gentamicin (120 mg/kg/day,ip) for 19 days where group ii given vehicle of 1% cmc,group iii and group iv were pre-treated 2 h before gentamicin by 4-methylcatechol (10 μg/kg,ip ) and silymarin (100 mg/kg,oral gavage),respectively. the main findings indicated that silymarin exhibited restoration of nerve growth factor (ngf) levels and increased tropomyosin-related kinase receptors-a (trk-a) m-rna expression in cochlear tissue and preservation of hair cells of organ of corti by scanning electron microscopy (sem) with significant decrease in auditory brainstem response (abr) threshold compared to 4-methylcatechol. only silymarin caused significant amelioration in oxidative stress state by reducing malondialdehyde (mda) levels and increasing catalase activity. conclusions: silymarin exerts superiority over 4-methylcatechol when recommended as protective agent against gentamicin ototoxicity based on its efficient neurotrophic and antioxidant activities. © 2014 institute of pharmacology,polish academy of sciences. published by elsevier urban & partner sp. z o.o. all rights reserved.