Involvement of PGE2 and TNF-α in LPS-tolerance in rat glial primary cultures

The effect of repeated exposure of primary newborn rat brain glial cultures to the endotoxin lipopolysaccharide (LPS), a component of Escherichia coli membrane, on PGE2 and TNF-α production was examined. PGE2 production by cell cultures exposed to LPS at a dose of 5 μg/ml, 4 and 24 h after initial exposure did not differ from PGE2 production by the same cultures 4 and 24 h after the first exposure to the same dose of LPS. TNF-α production was significantly lower with the second exposure as compared with the production by the same culture, exposed to the same dose of LPS, examined 4 and 24 h after the first exposure. We concluded that endotoxin tolerance in our culture model is associated with reduced secretion of TNF-α, caused by the initial exposure to LPS, while PGE2 production remained unchanged.