Immunoreactivity for brain-fatty acid binding protein in gomori-positive astrocytes

Gomori-positive (GP) astrocytes are a subset of brain astrocytes with highly stained cytoplasmic granules that arise from the degradation of mitochondria. The GP granules of these astrocytes are most prominent in the arcuate nucleus of the hypothalamus, but can also be detected in the olfactory bulbs, hippocampus, habenula, and other selected brain regions. The cause and functional effects of this mitochondrial pathology in these glia are not yet known with certainty. In other tissues, mitochondrial dysfunction is associated with elevations in cytoplasmic lipids and lipid-binding proteins, due to impaired mitochondrial oxidation of lipids. To see if GP astrocytic mitochondrial pathology is also associated with an elevation in lipid binding proteins, rat brain sections were stained for brain fatty acid binding protein (B-FABP), using immunocytochemistry. Astrocytes immunoreactive for B-FABP were much more abundant in brain regions enriched in GP astrocytes than in other brain regions. Semi-thin sections revealed that astrocytic B-FABP immunoreactivity was often, but not always, associated with GP cytoplasmic granules. These data suggest that GP astrocytes have an unusual lipid metabolism, which may relate to degenerative processes occurring in the selected brain regions that contain GP astrocytes.