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[Establishment of model with inner ear mimetic aging and mtDNA 4834 bp deletion in rats].

OBJECTIVE
To explore the establishment of the mimetic aging effect in the inner ear of the rat.


METHOD
Twenty-four Wistar rats were randomly divided into two groups: group A (D-galactose group, n = 14), which were treated with hypodermic 5% D-galactose (150 mg x kg(-1) x d(-1)) for 8 weeks and then with intraperitoneal saline for 10 days, and group B (control group, n = 10), which were given saline only. Auditory brainstem response(ABR) was used to detect the hearing threshold of rats, and colorimetry was used to analyze the activity of the glutathione peroxidase (GSH-PX). The inner ear tissue was harvested and mitochondrial DNA was amplified to identify the 4 834 bp deletion mutation by nested primer polymerase chain reaction (nested PCR) technique.


RESULT
The incidence of mitochondrial DNA 4 834 bp deletion of group A was 100% (28/28), while the deletion of group B was 0. The activity of the GSH-PX in group A (59.07 +/- 8.70 U) was lower than that in group B (142.10 +/- 7.02 U). The difference between group A and group B was significant (t-test, P < 0.01). Variation in ABR threshold of (5.36 +/- 3.08) dB peSPL was observed in group A, and (6.50 +/- 3.37) dB peSPL in group B. The difference in shift of ABR threshold between group A and group B was not significant (P > 0.05).


CONCLUSION
The mimetic aging effect in the inner ear of the rat can be induced by D-galactose, and this rat model presents high incidence of mtDNA4834 deletion. But no hearing loss was found in this model.