Uptake and subcellular distribution of 51Cr in Gomori-positive astrocytes in primary culture.
An unusual population of astrocytes containing Gomori-positive inclusions occurs in periventricular regions of the brain in all mammalian species. The inclusions are autofluorescent and exhibit non-enzymatic peroxidase activity. Estradiol treatment in vivo and cysteamine treatment in vitro have been shown to increase the number and size of these inclusions. Recent studies indicate that the Gomori inclusions are accumulations of autophagocytized abnormal mitochondria. The mitochondrial changes initiating Gomori inclusion formation begin with a loss of cristae. Energy dispersive X-ray microanalysis also reveals small emission peaks indicative of chromium. The appearance of chromium peaks in the initial stages of mitochondrial transformation suggests that enhanced permeability to chromium could play a causal role in generating Gomori inclusions. In the present study, we have examined the uptake and intracellular distribution of chromium during Gomori inclusion formation in cysteamine-treated cultured astrocytes. 51Cr was added to the media of glial cultures 24 hours prior to the initiation of the formation of Gomori inclusions by the addition of cysteamine. Cultures were fixed and prepared for EM radioautography at 12, 24, and 72 hours following the addition of cysteamine. 51Cr was added to control cells but they were not treated with cysteamine, and, they did not, therefore, develop Gomori inclusions. Cysteamine exposure resulted in a rapid sustained increase in radiolabel over the astrocytes. Much of the label was concentrated over mitochondria. At the late time points, label concentrated progressively over developing Gomori inclusions. These results confirm that the onset of Gomori inclusion formation coincides with increase cellular permeability to chromium and they indicate that uptake of chromium by mitochondria may play an important role in initiating development of these structures.
Brawer
J R
JR
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
Small
L
L
Wang
X
X
Schipper
H M
HM
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism* / Q000648:ultrastructure; D001345:Autoradiography; D002478:Cells, Cultured; D002857:Chromium / Q000378:metabolism*; D002860:Chromium Radioisotopes; D003543:Cysteamine / Q000633:toxicity; D004577:Electron Probe Microanalysis; D002479:Inclusion Bodies / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000378:metabolism / Q000648:ultrastructure
D002860:Chromium Radioisotopes; D002857:Chromium; D003543:Cysteamine