The effect of 6-aminonicotinamide on energy metabolism in rat embryo neural tube.

6-Aminonicotinamide (6-AN) is a potent metabolic inhibitor which produces central nervous system malformations when administered to pregnant rats. Since the antimetabolite interferes with energy yielding pathways, the present study was undertaken to determine the effect of maternally administered 6-AN on energy metabolism of the neural tube in developing embryos. On day 9 of gestation, pregnant rats were injected with 2 mg/kg 6-AN, and embryos removed 12 or 24 hours later. Glucose, glycogen, lactate, ATP, PCr, and GABA were measured in neural tube sections using fluorometric techniques. Only ATP and PCr showed changes as compared to appropriate controls. These two metabolites were increased 29% and 37%, respectively, by 6-AN administration. The mechanism of these alterations in metabolites is unclear, but may be related to decreased metabolic demand.