[Therapeutic effect of insulin-like growth factor-1 injection into the inner ears through scala tympani fenestration on gentamicin-induced hearing loss in guinea pigs].
OBJECTIVE
To study the therapeutic effect of insulin-like growth factor-1 (IGF-1) injection into the inner ears through a scala tympani fenestration on sensorineural deafness in a guinea pig model of gentamicin-induced hearing loss.


METHODS
Twenty guinea pigs with gentamicin-induced hearing loss were randomized equally into IGF-1 group and control group. In both groups, scala tympani fenestration was performed for injection of IGF-1 (10 microl) or artificial perilymphatic fluid (10 microl). Auditory brainstem responses (ABR) test was performed before and 7 and 14 days after surgery, respectively, and the cochlea was removed by decollation of 3 guinea pigs from each group after ABR test for observing the changes in the hair cells using scanning electron microscope.


RESULTS
Significant reduction in the ABR response threshold (RT) occurred in IGF-1 group 7 and 14 days after the surgery, and on day 14, ABR RT showed significant difference between IGF-1 group and the control group. Scanning electron microscopy revealed severer damages of the hair cells in the control group, and in the IGF-1 group, finger-like microvilli was detected on the surface of the damaged hair cells.


CONCLUSIONS
IGF-1 injection in the inner ear through the scala tympani fenestration may ameliorate the damages of the auditory function and relieve sustained toxicity of gentamicin in guinea pigs possibly by protection and partial repair of the damaged cochlea hair cells as well as protection of the afferent nerves.
Li
Yong-he
YH
Department of Otolaryngology and Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China. Liyonghe517@163.com
Chen
Hao
H
Guo
Meng-he
MH
D000818:Animals; D007758:Ear, Inner / Q000187:drug effects* / Q000503:physiopathology; D005839:Gentamicins; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000648:ultrastructure; D034381:Hearing Loss / Q000139:chemically induced / Q000188:drug therapy*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D012533:Scala Tympani
D005839:Gentamicins; D007334:Insulin-Like Growth Factor I