title: Neurotrophic and antioxidant effects of silymarin comparable to 4-methylcatechol in protection against gentamicin-induced ototoxicity in guinea pigs.
abstract: 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.
  
  
  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 2h before gentamicin by 4-methylcatechol (10 μg/kg, ip) and silymarin (100mg/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.
authors.affiliation: Department of Forensic Medicine & Clinical Toxicology, Faculty of Medicine, Tanta University, Tanta, Egypt.
authors.forename: Eman I
authors.initials: EI
authors.lastname: Draz
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Tanta University, Tanta, Egypt. Electronic address: amanyabdin@med.tanta.edu.eg.
authors.forename: Amany A
authors.initials: AA
authors.lastname: Abdin
authors.affiliation: Department of Histology, Faculty of Medicine, Tanta University, Tanta, Egypt.
authors.forename: Naglaa I
authors.initials: NI
authors.lastname: Sarhan
authors.affiliation: Department of Audiology, Faculty of Medicine, Tanta University, Tanta, Egypt.
authors.forename: Takwa A
authors.initials: TA
authors.lastname: Gabr
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002396:Catechols / Q000494:pharmacology*; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects / Q000502:physiology; D005839:Gentamicins / Q000009:adverse effects*; D006168:Guinea Pigs; D006312:Hearing Loss, Bilateral / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D020932:Nerve Growth Factor / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009925:Organ of Corti / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D018384:Oxidative Stress / Q000187:drug effects; D020917:Receptor, trkA; D012838:Silymarin / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D002396:Catechols; D005839:Gentamicins; D018696:Neuroprotective Agents; D012838:Silymarin; C018599:4-methylcatechol; D020932:Nerve Growth Factor; D020917:Receptor, trkA
keywords: Antioxidants; Gentamicin; Neurotrophic factors; Ototoxicity; Silymarin