[Detection of hearing threshold and polymorphic molecular marker analysis of guinea pigs of mimetic aging].
OBJECTIVE
To explore the establishment of the mimetic aging effect in guinea pigs induced by D-galactose, and to detect the biological indicatrix associated with hearing loss and provide a new tool for molecular pathogenesis of hearing loss.


METHODS
Total of 51 guinea pigs were randomly divided into three groups: group A (model aging group, n = 25), which were injected with D-galactose (200 mgxkg(-1)xd(-1)) by intra peritoneum for 6 weeks, group B (model control group, n = 18), which were given the same amount of saline only, and group C (vacant group, n = 15) were not treated. Then, The guinea pigs in group A and B were exposed in noise for 8 days, 8 hours once a day. Auditory brainstem response (ABR) was used to test the hearing threshold of guinea pigs thrice, first before the drug administered, then after 6 weeks the drug used, third after noise exposure. And colorimetry was used to analyze the activity of superoxide dismutase (SOD) and malon dialdehyde (MDA) in brain and liver tissue. The DNA of inner ear tissue was harvested and amplified fragment length polymorphism (AFLP) was used to detect the differential polymorphic markers.


RESULTS
After injection, there was no significant difference in elevation of ABR threshold between the group A and group B (t = 1.14, P > 0.05). However, exposure of noise later, elevation in ABR threshold of (22.97 +/- 10.56) dB peSPL was observed in group A, and (14.16 +/- 7.36) dB peSPL in group B. The was significant difference in variation of hearing threshold between group A and group B (t = 2.78, P < 0.05). The activity of SOD in brain and liver tissue in group A was lower than that in group B. the level of MDA was opposite between group A and group B. The difference between group A and group B was significant (P < 0.01). A differential polymorphic marker was observed by AFLP.


CONCLUSIONS
The mimetic aging effect of the guinea pigs can be induced by D-galactose, and this model can not directly induce the hearing loss. The differential polymorphic marker possibly act as a predisposing factor which can greatly enhance the sensitivity of the ear to the noise.
Mao
Min
M
Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Guangzhou Medical College, China.
Zhang
Jian-guo
JG
Tao
Ai-lin
AL
Yan
Xiao-ling
XL
Ouyang
Shun-lin
SL
Yuan
Xu-ping
XP
Qiu
Li-zi
LZ
Xie
Yang
Y
Zou
Ze-hong
ZH
Lu
Jie-zhen
JZ
Li
Qing
Q
D000375:Aging; D054458:Amplified Fragment Length Polymorphism Analysis; D000818:Animals; D001309:Auditory Threshold; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D005690:Galactose / Q000494:pharmacology; D006168:Guinea Pigs; D008297:Male; D011304:Presbycusis / Q000139:chemically induced / Q000503:physiopathology*
D005690:Galactose