DISTRIBUTION OF CALRETININ MESSENGER-RNA IN THE VESTIBULAR NUCLEI OF RAT AND GUINEA-PIG AND THE EFFECTS OF UNILATERAL LABYRINTHECTOMY - A NONRADIOACTIVE IN-SITU HYBRIDIZATION STUDY

We examined the localization of neurons expressing mRNA for calretinin , a cytosolic EF hand calcium-binding protein, throughout the vestibul ar nuclei of rat and guinea pig by non-radioactive in situ hybridizati on, using an alkaline phosphatase labeled oligonucleotide probe. Label ed cells were particularly numerous in the medial vestibular nucleus ( mVN) and their distribution was similar in rat and guinea pig, and pre sented a characteristic rostrocaudal and mediolateral pattern. The eff ects of hemilabyrinthectomy were assessed at various times post lesion from 10 h to 30 days by comparison of the pattern of labeling in the ipsi- and contra-lateral vestibular nuclei of guinea pig. After up to 48 h no modification in the calretinin mRNA distribution was detected. After 3 to 30 days of survival, there was a decrease (about 30%) of t he calretinin expressing neurons in the nucleus on the side of the les ion. The unilateral sensory deprivation seemed to induce a permanent a symmetry in the expression of calretinin which was not abolished after vestibular compensation. These results suggested that the calretinin expression in these neurons depends upon the integrity and activity of sensorineuronal peripheral vestibular influences.