Lipopolysaccharide-preconditioning influences the NO secretion from cultured cerebral astrocytes and microglia in vitro

OBJECTIVE:To study the influences of lipopolysaccharide(LPS)preconditioning on NO secretion in cultured cerebral astrocytes and microglia.METHODS:Mice cerebral astrocytes and microglia were isolated and purified in vitro.Thereafter,these glial cells were divided into 4 groups:LPS-primed group,10 ng/ml LPS treated group,1μg/ml LPS treated group and non-treated group.The LPS-primed group was preconditioned with 10 ng/ml of LPS for 18 hours.After the preconditioning,the cells received the second treatment with 1μg/ml of LPS for 6 hours, 24 hours and 48 hours.Then cultured supernatants of all 4 groups were collected.NO level in the supernatants was determined by Griess method.RESULTS:Both in cultured astrocytes and microglia,NO level of the LPS-primed group was increased at 24 hours with LPS re-treatment compared with the 1μg/ml LPS-stimulated group(P0.05).Moreover, at 48 hours with LPS re-treatment,a long-lasting and significant enhancing effect was found in astrocytes(P0.05). CONCLUSION:LPS preconditioning could enhance NO secretion ability in cultured cerebral astrocytes and microglia.