Regeneration of the central auditory pathway in adult rats.

Regeneration of the auditory pathway in the central nervous system, which has not been reported previously, was investigated in adult rats. The ventral cochlear tract (VCT) in the medulla oblongata of adult rats was completely transected unilaterally by a ventral approach through an opening in the basioccipital bone. After postoperative intervals of 1 day to 3 months, the cochlear tract was examined by an anterograde tracing method using wheat germ aggulutinin-conjugated horseradish peroxidase (WGA-HRP) injected unilaterally in the ventral cochlear nucleus (VCN) ipsilateral to the lesion. In this simple transection experiment no regeneration was observed. However, when embryo brainstem tissue was transplanted on the transected site, regeneration occurred in about 30% of the rats examined. These results indicate the occurrence of obvious regeneration in the central auditory pathway, which was previously thought not to be restored once damaged, and they raise hope for future treatment of humans.