GFA-protein gene expression on the astroglia in cow and rat brains

The distribution of messenger RNA for glial fibrillary acidic protein (GFA-protein) of cow and rat brains was studied by an in situ hybridization technique using a tritium-labeled cDNA probe and autoradiography. The results were compared to the findings of GFA-protein immunohistochemistry. The signals of GFA-protein mRNA were detected on the perikaryal cytoplasm of astroglia observed in the following areas: the subpial area and the white matter of the cerebrum and cerebellum of the cow and the rat; gray matter of cow spinal cord; the thalamus, pontine reticular formation and white matter of the rat brainstem. All of these areas contain astroglia which are strongly positive for GFA-protein immunohistochemistry. On the other hand, we could detect no GFA-protein mRNA-positive glial cells in the areas where astroglia are negative for this immunostaining. These results indicate that the regional differences in the amount of GFA-protein in astroglia depend primarily on the degree of expression of their GFA-protein gene.