POSTNATAL-DEVELOPMENT OF GABA-LIKE AND GLYCINE-LIKE IMMUNOREACTIVITY IN THE COCHLEAR NUCLEUS OF THE MONGOLIAN GERBIL (MERIONES-UNGUICULATUS)

The maturation of the morphological substrate for inhibitory interacti ons was investigated in the cochlear nucleus of the gerbil with immuno cytochemistry for gamma aminobutyric acid (GABA) and glycine on altern ating vibratome sections. The patterns of immunostaining obtained with both antibodies in the adult closely conformed to the general mammali an scheme. Qualitative analyses revealed an age-related increase in st aining intensity and in the relative numbers of immunolabelled cells a fter birth up to the age of 3-4 weeks. As early as birth and in all su bdivisions of the cochlear nucleus, a few labelled cells and puncta in the sections were stained either with the GABA or the glycine antibod y. Immunoreactive puncta and cells were, however, far less abundant th an in the adult, and the staining intensity of cells was only weak. Th e most strikingly GABA-immunolabelled cells at birth were the Golgi ce lls of the granule-cell domains. The numbers of weakly GABA- and glyci ne-immunostained cells of the dorsal cochlear nucleus clearly increase d between birth and the third postnatal week. At approximately the ons et of hearing (postnatal day 12-14), some cells of the dorsal cochlear nucleus and small cells of the ventral cochlear nucleus gained adult- like GABA-staining properties. Almost adult-like labelling intensity w as observed in glycine-immunoreactive cells of the deep dorsal cochlea r nucleus and in some small cells of the ventral cochlear nucleus. Pun cta staining to both antibodies appeared adult-like throughout the coc hlear nucleus. About 2 weeks after the onset of healing (at the latest ), adult-like staining of all subsets of immunoreactive cells occurred throughout the cochlear nucleus in all specimens.