Xenobiotic-mediated production of superoxide by primary cultures of rat cerebral endothelial cells, astrocytes, and neurones

Previous works of our group demonstrated that xenobiotic metabolism by brai n microsomes or cultured cerebral cells may promote the formation of reacti ve oxygen species. In order to characterise the risk of oxidative stress to both the central nervous system and the blood-brain barrier, we measured i n the present work the release of superoxide in the culture medium of rat c erebrovascular endothelial cells during the metabolism of menadione, anthra quinone, diquat or nitrofurazone. Assays were run in the same experimental conditions on primary cultures of rat neurones and astrocytes, Quinone meta bolism efficiently produced superoxide, but the production of radicals duri ng the metabolism of diquat or nitrofurazone was very low, as a probable re sult of their reduced transport inside the cells. In all cell types assayed , superoxide production was time-and concentration-dependent, and cultured astrocytes always produced the highest amounts of radicals. Superoxide form ation by microsomes prepared from the cultured cells was decreased by immun oinhibition of NADPH-cytochrome P450 reductase or by its irreversible inhib ition by diphenyliodonium chloride, suggesting the involvement of this flav oprotein in radical production. Cerebrovascular endothelial cells cultured on collagen-coated filters produced equivalent amounts of superoxide both a t their luminal side and through the artificial basement membrane, suggesti ng that in vivo, endothelial superoxide production may endanger adjacent as trocytes and neurones. (C) 2000 Elsevier Science B.V. All rights reserved.