F. Shoji et al., Glial cell line-derived neurotrophic factor has a dose dependent influenceon noise-induced hearing loss in the guinea pig cochlea, HEARING RES, 142(1-2), 2000, pp. 41-55
We examined the effectiveness of glial cell line-derived neurotrophic facto
r (GDNF) to attenuate cochlear damage from intense noise stress. Subjects w
ere exposed to 115 dB SPL one octave band noise centered at 4 kHz for 5 h.
They received artificial perilymph with or without GDNF into the left scala
tympani at 0.5 mu l/h from 4 days before noise exposure through 8 days fol
lowing noise exposure. Different concentrations of GDNF (1 ng/ml, 10 ng/ml,
100 ng/ml, and 1 ng/ml) were applied chronically directly into the guinea
pig cochlea via a microcannula and osmotic pump.:Noise-induced hearing loss
was assessed with pure tone auditory brainstem responses (at 2, 4, 8 and 2
0 kHz), measured, prior to surgery, 1 day before noise exposure, and 7 days
following noise exposure. Subjects were killed on day 8 following exposure
for histological preparation and quantitative assessment of hair cell (HC)
damage. A dose-dependent protective effect of GDNF on both sensory cell pr
eservation and hearing function was found in the treated ears. At 1 ng/ml,
GDNF showed no significant protection; at 10 ng/ml, GDNF showed significant
HC protection; and at 100ng/ml, it was greater and bilateral. At 1 mu g/ml
, GDNF appeared to have a toxic effect under noise stress in some cochleae.
These findings indicate that GDNF at certain concentrations can effectivel
y protect the inner ear from noise-induced hearing loss. (C) 2000 Elsevier
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