Correlation between P0 protein purified from the inner ear and auditory neuropathy.

Objective To purify P0 protein from guinea pigs′ inner ears by preparative SDS-PAGE and to study the correlation between P0 protein and auditory neuropathy.Methods A mixture of membranous proteins of the inner ears was separated by preparative SDS-PAGE.The corresponding band at 30 000 was cut and electrally eluted.The collected proteins were identified by Western blot assay.A group of 20 healthy Sprague-Dawley rats were immunized with P0 protein emulsified in complete Freund′s adjuvant,and another 20 Sprague-Dawley rats immunized with complete Freunds adjuvant only were used as contro1s.The rats′ hearing thresholds,serum IgG level and morphological changes in the cochlear nerve were investigated.The distribution of P0 protein in the cochlear nerve was detected by immunohistochemical technique.Results The purity of the protein was demonstrated by a single band at the 30 000 site in SDS-PAGE,which was identified as P0 protein by western blot analysis assay.About 29.4% of P0-immunized rats showed increased hearing thresholds and elevated IgG level(P0.05),and the demyelination of the cochlear nerve was observed by an electron microscope.P0 protein was distributed in the myelin sheath of the cochlear nerve.Conclusions P0 protein from guinea pigs′ inner ears can be successfully purified by preparative SDS-PAGE and an animal model of demyelination induced by P0 protein was successfully established,which is very useful to research the mechanism of auditory neuropathy.