ACUTE ENERGY DEPRIVATION SYNDROMES - INVESTIGATION OF M-DINITROBENZENE AND ALPHA-CHLOROHYDRIN TOXICITY ON IMMORTALIZED RAT-BRAIN MICROVESSEL ENDOTHELIAL-CELLS

Acute energy deprivation syndromes share a common pattern of CNS patho logy resulting in symmetrical spongiform brain stem lesions in rodents . However, some toxicants are proposed to act on astrocytes alone (alp ha-chlorohydrin) whilst others are associated with petechial haemorrha ges and blood-brain barrier (BBB) breakdown (m-dinitrobenzene). In thi s study, we investigated the toxicity of alpha-chlorohydrin (alpha-CH) and m-dinitrobenzene (m-DNB) in an in vitro BBB model, the rat brain capillary endothelial cell line RBE4. Cytotoxicity was observed after treatment of RBE4 cells with both toxicants, as manifested by a decrea se in protein content and MTT reduction (3-[4, 5-dimethylthiazol-2-yl] -2, 5-diphenyltetrazolium bromide) over control values at concentratio ns greater than or equal to 1 mM for m-DNB and greater than or equal t o 20 mM for alpha-CH. m-DNB caused a dose-dependent increase in glucos e consumption and lactate production in RBE4 cells, while alpha-CH had no effect on these parameters. The distribution of F-actin at the cel l margin observed in control cultures was changed to a diffuse pattern over the cell cytoplasm after treatment with both toxins at subcytoto xic concentrations. However, a reduction in F-actin content was only o bserved at concentrations greater than or equal to 1 mM for m-DNB and greater than or equal to 20 mM for alpha-CH. The permeability of RBE4 cell monolayers cultured on filters above primary rat astrocytes was m easured using C-14-sucrose (M.Wt. = 342) and FITC-dextran (M.Wt. = 400 0). m-DNB (0.5 mM) increased the permeability of RBE4 cell monolayers to both tracers, while alpha-CH (30 mM) had no effect. The results fro m this study indicate that m-DNB may have direct toxic effects on brai n endothelial cells which lead to loss of barrier function. Whilst alp ha-CH caused some toxic effects in RBE4 cells, if did not alter endoth elial cell monolayer permeability. (C) 1997 Intox Press, Inc.