Quinolinic acid in children with congenital hyperammonemia

Abstract

Levels of the excitotoxin quinolinic acid (QUIN) were measured in the cerebrospinal fluid of infants and children with congenital hyperammonemia. Twofold to tenfold elevations of QUIN were found in 4 neonates in hyperammonemic coma (QUIN range, 250–990 nM; control mean, 110 ± 90 nM; p < 0.005). Similar elevations of neopterin were found (range, 24–75 nM; control mean, 9.0 ± 4.9 nM; p < 0.005). In addition, significant elevations of QUIN were found in 14 older children with congenital hyperammonemia (mean, 50 ± 20 vs 17 ± 6 nM; p < 0.05). Neopterin levels were not elevated in these children. The QUIN may originate from an increase in tryptophan transport across the blood-brain barrier or from induction of indolamine-2,3-dioxygenase activity. These findings support a role for QUIN in the neuropathology of congenital hyperammonemia. They also suggest the potential utility of N-methyl-D-aspartate receptor–-blocking agents or inhibitors of QUIN synthesis in the treatment of hyperammonemic coma.