Glia activation induced by peripheral administration of aluminum oxide nanoparticles in rat brains.

With the wide application of nanoscaled particles, the risk of human exposure to these particles has been markedly increased. However, knowledge about their safety falls far behind the utility of these nanoparticles. Here we have analyzed the activation of brain microglia and astrocytes, which are sensitive to changes of brain environment after peripheral exposure to nanoscaled aluminum oxide suspension. Sprague-Dawley rats (six rats per treatment) were intraperitoneally injected once every second day for 30 or 60 days with nanoscaled aluminum oxide (NSAO; 1 mg/kg or 50 mg/kg), non-nanoscaled aluminum oxide (nNSAO, 1 mg/kg), or vehicle (saline). After 60 days' exposure the numbers of ED1+, GFAP+, and nestin+ cells in cortex and hippocampus were significantly higher in NSAO-treated rats than nNSAO- or vehicle-treated rats; thus, compared with nNSAO, NSAO has potential effects on the innate immune system of rat brain. This should be considered when evaluating the toxicological effects of nanosized particles. FROM THE CLINICAL EDITOR: Sprague-Dawley rats were intraperitoneally injected with nanosized aluminum oxide, (NSAO); non-nanoscaled aluminum oxide, or vehicle (saline). The numbers of ED1+, GFAP+, and nestin+ cells in cortex and hippocampus were significantly higher in NSAO-treated rats than nNSAO- or vehicle-treated rats; thus, NSAO has potential effects on the innate immune system of rat brain.