COMPOSITION OF GOMORI-POSITIVE INCLUSIONS IN ASTROCYTES OF THE HYPOTHALAMIC ARCUATE NUCLEUS

Background: Astrocytes within the hypothalamic arcuate nucleus contain Gomori-positive inclusions that exhibit a nonenzymatic peroxidase act ivity. The source and composition of these Gomori-positive inclusions are currently unknown. Recent evidence, derived from cultured astrocyt es, suggests that Gomori-positive inclusions may consist of autophagoc ytized accumulations of altered mitochondria and that the peroxidase a ctivity is generated by iron or other metals which accumulate in these mitochondria. Methods: The present study applies electron microscopy, energy dispersive X-ray microanalysis, and immunocytochemistry in con junction with confocal microscopy to determine the structure and compo sition of Gomori-positive inclusions in vivo. Results: The results ind icate that Gomori-positive inclusions are heterogeneous structures oft en associated with microtubules and that they contain conspicuous mito chondrial components. Gomori-positive inclusions exhibit X-ray emissio n peaks for copper and, less often, chromium, either of which could ac count for the peroxidase activity. Conclusions: These results support the hypothesis that Gomori-positive inclusions are autophagosomes in w hich mitochondria are prominent. (C) 1994 Wiley-Liss, Inc.