MATERNAL DIETARY CARBOHYDRATE RESTRICTION INFLUENCES THE DEVELOPMENTAL PROFILE OF POSTNATAL RAT BRAIN INDOLEAMINE METABOLISM

Dietary glucose restriction during pregnancy can retard fetal brain de velopment, lower term brain glycogen levels and adversely affect the s erotonergic neurotransmitter system in the fetus. To study if the post natal profile of brain indoles continues to respond to these diet-indu ced changes, pregnant rats were fed graded levels (0, 12, 24, 60%) of glucose from impregnation to day 15 postpartum, and neonatal brain mea surements were made. A steady decrease in tryptophan levels, a steady increase in 5-hydroxytryptamine (5-HT) levels and a U-shaped change in 5-hydroxyindoleacetic acid (5-HIAA) were observed during the first 15 postpartum days. Superimposed on these development profiles was a tem porary surge in the concentrations of all three indoles 24 h after bir th, which was dramatic for tryptophan and more modest for 5-HT and 5-H IAA. The level of carbohydrate in the maternal diet significantly infl uenced the magnitude of this increase in tryptophan, 5-HT and 5-HIAA a t 24 h: the values were significantly higher in the carbohydrate-restr icted (12 or 24%) rat pups when compared with control or carbohydrate- free (0% glucose) offspring. No effects of dietary treatment were appa rent by day 6. However, the reemergence of a significant difference in brain 5-HT content at day 15 postpartum indicates that even when ener gy intake is adequate the level of carbohydrate in the maternal diet m ay continue to play a role in modulating serotonergic neurotransmitter levels later in development.