DEVELOPMENTAL EXPRESSION OF THE GLYCINE TRANSPORTERS GLYT1 AND GLYT2 IN MOUSE-BRAIN

Using immunocytochemical localization, the distribution of the glycine transporters GLYT1 and GLYT2 in the developing mouse brain was studie d, GLYT1 and GLYT2 immunoreactivity begins during the period of fiber outgrow and synaptogenesis, GLYT2 is first expressed in spinal and spi nothalamic white matter and is followed by the expression of synaptoph ysin. in the postnatal stages, GLYT2 staining in the white matter disa ppears, and a punctuated pattern in the gray matter emerges. in contra st, in the fetal brain GLYT1 immunoreactivity coincides with gray matt er neuropil and processes of radial glia. GLYT1 is distributed over a much wider area of the brain than GLYT2. However, the distribution of these two GLYTs implies that GLYT1 and GLYT2 operate in concert within the area where both are present. At the day 12 embryo stage, GLYT1 an tibodies stain the liver, and later they also react with the pancreas and the gastroduodenal junction, No other organs exhibit significant G LYT1 immunoreactivity. We additionally observed the presence of GLYT1 in rat fetal cerebral cortex and hippocampus, which was not detected i n fetal mouse brain. Moreover, GLYT1 immunoreactivity was found in the mouse floor plate and the Ventral commissure but was not present in t he same regions in rats. These findings suggest possible differences i n the expression of GLYT1 between these two species.