Experimental observation on the hearing and cochlear histochemistry and immunohistochemistry in senil rats

The auditory brain stem response （ABR） was recorded in natural senil and adult rats, by use of histochemistry staining of NSE, S 100 in the cochla. The results showed that the threshold of ABR in senil rats was noticeably increased, the histochemical activity of SDH and immunohisto chemical activity of NSE and S 100 were singnificantly decreased. Lipofuscin accumulated within the spiral ganglion cells and nerve fibre atrophy also found in the senil rat's cochlea. The results suggest that ageing of hearing is mainly connected with the cochlea rather than the brain stem.