The expression of inducible nitric oxide synthase in cochlea of aged guinea pigs

Objective To determine the expression of inducible nitric oxide synthase (iNOS) in cochlea of the aged guinea pigs. Methods Twenty guinea pigs were divided into two groups: experimental group(33 35 months old) and control group(2 3 months old). The threshold of auditory brain stem response (ABR) of two groups was measured, iNOS was examined in the cochlea of both groups using immunohistochemical method. Results The ABR threshold of coantor group was (22 0±5 3) dBspL, and the experimental group was (50 0±10 5) dBspL, There was a significant difference in ABR threshold between two groups ( P 0 05).The iNOS was expressed in stria vascularis and spiral ganglion cell of the cochlea of experimental group, and was not expressed in the control group. Conclusions The expression of iNOS was positive in the cochlea of the aged guinea pigs. It suggests that nitric oxide (NO) takes a very important role in the aging process of cochleas of guinea pigs.