Quinolinic acid is a potent lipid peroxidant in rat brain homogenates

In this study, we describe the lipoperoxidative effect of quinolinic acid (QUIN) in vitro. The formation of thiobarbituric acid reactive products (TBA-RP), an index of lipid peroxidation, was measured in rat brain homogenates after incubation at 37 degrees C for 30 min in the presence of QUIN and some structurally and metabolically related compounds such as Kynurenine, Kynurenic acid, Glutamate, Aspartate and Kainate. Concentrations of QUIN in the range of 20 to 80 microM increased lipid peroxidation in a concentration-dependent manner from about 15% to about 50%. Kynurenic acid, a compound metabollically related to QUIN that can block its neurotoxic actions in vivo, also inhibited completely the QUIN-induced TBA-RP formation in our system. Lipid fluorescent material, another index of lipid peroxidation was also found increased by 49% after incubation with 40 microM QUIN. It is concluded that lipid peroxidation may be a damaging process involved in the neurotoxicity of QUIN.