An assessment of cochlear hair-cell loss in insulin-dependent diabetes mellitus diabetic and noise-exposed rats.
OBJECTIVE
The purpose of this study was to investigate if insulin-dependent diabetes mellitus causes degenerative changes in the inner ear and whether these changes are exacerbated by noise exposure.


METHODS
Insulin-dependent diabetes mellitus was induced in male rats using streptozotocin (65 mg/kg of body weight, intravenously). Half the animals were exposed to 95 dB of random noise for 12 hours per day over a period of 6 months. The cochleae were removed, fixed, decalcified, dissected, and the hair cells counted.


RESULTS
A significant loss of outer hair cells was exhibited in both noise-exposed groups; however, although there was no significant difference between these two groups, the noise-exposed diabetic animals had significant loss in more turns than did the noise-exposed control animals. The diabetic animals were not statistically different from the control animals.


CONCLUSIONS
These results suggest that insulin-dependent diabetes mellitus may increase the hair-cell loss caused by noise overstimulation.
Raynor
E M
EM
Division of Otolaryngology-Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, USA.
Carrasco
V N
VN
Prazma
J
J
Pillsbury
H C
HC
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000473:pathology; D006199:Hair Cells, Auditory, Inner / Q000473:pathology; D018072:Hair Cells, Auditory, Outer / Q000473:pathology*; D008297:Male; D009622:Noise / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley