DIFFERENTIAL CELLULAR-DISTRIBUTION OF GLUTAMATE AND GLUTAMINE IN THE RAT VESTIBULAR ENDORGANS - AN IMMUNOCYTOCHEMICAL STUDY

The cellular and subcellular localization of glutamate and glutamine i n the rat vestibular endorgans was studied by means of postembedding i mmunocytochemistry. Glutamate immunoreactivity was preferentially dist ributed in the hair cells, whereas glutamine immunoreactivity was enri ched in supporting cells. This points to a metabolic compartmentation similar to that found in glutamatergic nerve terminals and adjacent gl ial processes in the central nervous system. The present immunocytoche mical results are consistent with the existence of a glutamate-glutami ne cycle in the vestibular sensory epithelium. Our data are also in ag reement with a transmitter role of glutamate in both types of hair cel l, although a vesicular enrichment of glutamate in these cells remains to be demonstrated.